Coventry Very Light Rail | Hacker News Reader

Coventry Very Light Rail

coventry.gov.uk

209 pointsKaibeezy281 comments

Comments so far are not discussing what makes this light rail “very” light, so here’s an excerpt. The project claims to cost half of “normal” light rail.

> The vehicle is battery-powered, eliminating the need for overhead wires. It features an innovative turning system, enabling it to handle 15m radius curves. This allows for installation in tight corners within the existing highway. The Council intends for it to operate at a high frequency, providing a turn-up-and-go service. The vehicle has a capacity of 56, is comfortable and has low floors to enable passengers to embark and disembark easily. The vehicle has been developed to allow autonomous operation in future.

> The new track is laid just 30cm within the road’s surface, minimising the need to relocate pipes and cables, which is time-consuming and expensive. It achieves this by leveraging cutting-edge materials science, while still utilising standard rail parts to ensure ease of manufacture.

These things are tiny! I've traveled in larger airport shuttles.

It feels like that's putting this into a really awkward place in the tradeoff space. Trams work because they can scale higher than buses. That scale comes at the cost of more up-front infrastructure, much less flexibility, and needing dedicated lanes. So cities don't have trams everywhere, but they're only installed on routes that can support the scale.

For these you still have the up-front investment (just less of it) and inflexibility, but don't get the efficiencies of scale due to how small the capacity is.

Is this really just a bet that they can get autonomous tram-driving on city street approved a decade+ sooner than autonomous buses?

Tiny might make sense if they are running every 2 minutes and thus getting their capacity via frequency. However there is no reason to think they will do that. (if they were running anywhere near that frequent overhead wire would be a lot cheaper than a battery on every tram)

Yeah but you could do that with a bus today without miltiions in infrastructure spending

Not really because buses get stuck in traffic all the time because there’s a point where they need to share roads with cars. Once you spend the money on segregating buses entirely, you’re at the same level as the tram line.

Also, because of the expensive infrastructure that can only be used by trams, there’s a permanence there that prevents future politicians from ripping it out to put more cars on for a quick political win with drivers.

Going back to point 1: having a line means that any route needs to be properly planned because you never have an escape hatch of “just stick them on the road.” Example: where I live, the council installed a bus lane and a cycle lane. Where it pinches in (planning fuck up), it dumps all the traffic into a shared route with 2 roundabouts and 5 exits, each with an insane amount of traffic coming to or from them. Buses that are forced to use that route are always late. It takes me just as long to drive as it does to take the bus, faster if you factor in me waiting for a late bus.

Trams very often still share the road with cars.

The Nottingham tram, not far from Coventry, usually only shares road with cars in the city centre which is mostly pedestrianised. So mostly avoids commute traffic.

Not for all of the route, typically. Metrolink only in the city centre then it turns into a Metro line for the rest of the commuter route.

Quite a few do, and the point remains that sharing or not sharing the space with cars isn't a feature that distinguishes trams from buses. You'll can - and do - have dedicated rights of way for both, and you can - and do - share routes with cares for both.

I know of no bus routes that completely separate from cars beyond a strip of paint. I also know of no countries that give buses automatic priority over cars outside of bus lanes.

they exist several places. Brisbane comes to mind but there are others

LA metro G line is a brt with its own private guideway. Supposedly the bus network has been getting more signal priority.

> Not really because buses get stuck in traffic all the time because there’s a point where they need to share roads with cars.

Like many tram lines, CVLR is being laid in-road and not segregated. In fact, while not mentioned here, the it's 15 m turning radius is so important is because it's planned to traverse roundabouts in-lane.

The solution to that is dedicated bus lanes, which are quite common in some cities. Usually they allow taxis and emergency vehicles as well.

Trams here in Berlin share the street with the cars on some streets. So, it's exactly like a bus that can get stuck in traffic (and they do). Dedicated tracks are also common but they take up a lot of space and it's expensive infrastructure to install. Mostly trams are limited to the former East Berlin, though they've started to spread to some parts on the west side.

With electrical buses and bus lanes, you get most of the advantages of trams. There are probably still some advantages to dedicated tram lines. But they are expensive to install. I'm not sure it's worth the investment.

It's not uncommon at all in London to have a traffic jam in a bus lane just from the volume of buses and taxis

Step 1: Remove taxis from your bus lanes.

You missed this part:

> Also, because of the expensive infrastructure that can only be used by trams, there’s a permanence there that prevents future politicians from ripping it out to put more cars on for a quick political win with drivers.

A few things to further this:

- I’ve seen bus lanes get ripped out and moved around, you can see where the paint was cut off.

- Taxis use bus lanes, usually.

- People use bus lanes illegally if they’re not enforced with cameras (political cost of installing the cameras).

This is definitively not true. It's something people said about the Washington, DC streetcar and it turns out they are about to remove the streetcar in order to replace it with buses:

https://www.railwaygazette.com/light-rail-and-tram/dc-street...

I would have hoped it was clear that I never stated infrastructure was never ripped out, since there have been numerous examples of this happening, including my own home city. I’m merely making the point that tearing up tram lines is more costly than simply paying someone to cut paint lines off the road. That plus the initial investment creates an inertia against undoing it, though nothing prevents politicians pissing public money up the wall if they’re determined enough.

there have been no trams in my city for 70 years, but the tracks are still there in places. Trams are no more perminate than buses.

The main operating cost of running a bus line is the salary of the bus driver. It dwarfs vehicle maintenance cost and petrol. The VLR has the ambition to run autonomously eventually. Autonomous buses are quite a bit further into the future.

I didn't really mean that they needed higher capacity. If they had the passenger volume to justify such high intervals, they'd already have real trams.

But rather, this is giving up the benefit trams have over buses, without gaining any new edge to replace it. So why is it a good tradeoff? And why now, not 20 years ago?

The autonomous driving angle is the only idea I have.

A bus cannot be run ever two minutes. No amount of dispatch anywhere has pulled that off. I'm not sure if a tram can be run that often but subways are

Bus Rapid Transits can operate at frequencies of about 10 seconds per bus. Obviously they're highly parallelised to achieve that and have special infrastructure to enable it like dedicated stations and pedestrian access, so it's not just "a bus", but bus-based systems are how many of the very highest-throughput public transportation lines function, with up to 35000 people per hour per direction with three digit numbers of buses per hour.

For comparison, the most frequent London underground service is 100 seconds per train and the system moves about 50k passengers an hour (based on a 21% increase representing 10k passengers, I couldn't find a direct figure), presumably that being both directions.

What single BRT line runs at that capacity?

Probably the Rio de Janeiro one. The BRS Presidente Vargas corridor has a peak frequency of 600/hour, according to this site [0]. Pretty impressive IMHO.

[0]: https://brtdata.org/location/latin_america/brazil/rio_de_jan...

So you're just talking a ton of buses down the same road?

BRTs corridors often have dedicated stations with passing/bypass lanes and dedicated pedestrian access, but in the same way that subways and light rail are just a ton of trains down the same track, pretty much.

I've used a bus service that ran buses every five minutes. It was eventually replaced by a tram.

I don’t know if two minutes are possible, but in Berne, Switzerland, the bus line 10 runs every three minutes. Parts of the loop have dedicated bus lanes, but it‘s probably less than a third of the distance.

PDF: https://www.bernmobil.ch/sites/default/files/2025-02/ah_0201...

Buses can hit that on interleaved lines. Here is a bus lane in downtown LA that moves 70 buses an hour:

https://x.com/metrolosangeles/status/1153807208229957632

That is in the article. The intention is a frequent, arrive and go service. Maybe every 2, 5, 10 minutes, whatever the actual details will be, that is the goal.

Trams don't actually scale higher than busses; the highest ridership BRTs have far more ridership than the highest ridership light rail. The key thing that makes it work is having a dedicated right of way. I expect busses get a bad rap as a scaled transit solution mostly because they have to share the roads so often. But it's indeed an advantage of light rail that it's a lot harder to make that mistake with it.

Those BRTs will have lower passenger/operator ratios though since trams tend to be bigger than articulated buses and are frequently coupled together for busier routes.

I definitely agree that the dedicated right of way is the main thing. It's why some of San Francisco's trams are so slow outside of the city centre (where they run in a tunnel) and why Manchester's trams are so slow through the city centre (where they run at surface level sharing the street with pedestrians.)

Absolutely! I’ve used the Manchester Metrolink and it definitely slows down in the city centre. It does speed up a lot (and likely beats bus in rush hour) when you’re off the streets, which makes it an incredible commuter option!

Much of it is built on repurposed heavy rail lines and those sections are great. The Eccles Line through Salford Quays is horribly slow and windy though which was a pain for commuting to Media City from south east Manchester.

I believe the new Trafford line improves things somewhat but Manchester really needs much more heavy rail capacity.

The line out to the airport isn't using an old rail line and is fairly slow.

I think the up front investment is quite literally the problem this is solving for. If it weren't, you would just use light rail.

The ability for the tracks to be laid so shallow is in my view, the entire innovation and cost is the reason for this approach.

If higher capacity is needed you can always link multiple units together

In CVLR, you actually cannot as the extreme bogey angles mean they can only operate individually. You also can't order longer cars.

You can run them at high frequency though.

With computerized control and a comms link between the vehicles, you could probably have one vehicle follow 1m behind another, so they are effectively a train. If you still have a driver at all, you only need one in the front vehicle.

I don't think you could do that for CVLR specifically as it's not segregated from traffic and the second car would have to react individually to vehicles, pedestrians, roundabouts, etc.

If it's really just 1m behind, it doesn't need to respond individually to anything except pedestrians. And you can solve that with some extensible tapes that actually do connect the vehicles to prevent pedestrians walking between them.

Linking multiple units means making the stations longer. A more likely scenario is to deploy more units and deal with staffing by migrating to autonomous operation.

Buses on dedicated lanes are OK indeed. However, buses are simply not as comfortable as trams: roads unless in tiptop shape are not as smooth as rail, and bus drivers always take corners too fast.

Having to hold on to something discards it from my preferred list of solutions.

Have recently read Gareth Dennis’ How Railways will fix the Future…

It’s a worthwhile read BTW

I suspect these are too small to carry a significant number of passengers per hour

They’ll also probably never be autonomous as the challenge with autonomous is less the driving and more with passengers getting on and off, getting trapped etc

I'd assumed the point of them was that you can take the several cars of a tram and split them up to have more frequent services. Though I suppose this would compound with the cost of having a driver on each car, potentially cancelling some of the gains from cheap installation. As for the point of automation, I think the tram can probably be a lot easier than the bus because of the human factor. It seems safer, so legislators will be more willing to legalise it and residents less likely to complain. Also, you've got rails in the road that clearly mark the route of the tram which make it more visible than an automated bus. Most of these automated taxi companies still have a human supervising the process, and I imagine that could be employed here to good effect and with fewer or faster manual interventions than would otherwise be needed.

Even if all that falls through, I'm not gonna complain about it. We sorely need more public infrastructure in the UK. Even if an experiment like this fails, at least you actually get a tram line and experience out of it. Much better than a project which sucks up million then gets cancelled. (Cough cough HS2.)

Trans don’t need dedicated lanes, not sure where you got that idea from. Trains do.

Buses however are slow (in London about the same as walking) and (outside London) prone to vanishing on timetable changes. Closing a rail link is tricky, you can be confident that if you live near a tram stop it will be there in 10 years. 60% of our local (say 10 mile radius) buses have been removed in the last decade, removing entire villages from service.

A rail solution allows you to read, a bus throws you around everywhere and makes you sick.

Trams can be removed too. Bristol used to have trams. I doubt it is alone.

I definitely feel like trams are a weird technical solution to a policy/perception problem. On a technical level I don't think there's that much to recommend them over buses with bus lanes. It's just that governments never put bus lanes the whole way like you are forced to do with a tram.

Trams are much smoother than buses. I suspect that a bus can be made as comfortable as a tram with active suspension optimising ride quality, but I've never come across one. Jerky starts and stops, swinging around, kneeling for (dis)embarkation; these all make the ride unpleasant for users. Trams exclude those at the cost of additional up front infrastructure costs.

I can easily read a book on a tram. No chance on a bus (unless we want vomit all over the seats).

I agree, but I don't think that really matters. I mean nobody is going to spend millions on a tram just because it's a bit smoother.

It's a nice bonus; not a reason to build trams.

On the contrary, it's the reason we should build more trams. If the objective is to have more people using public transport, then we need to make them as nice as possible for people to use. Comfort is the user facing benefit of trams.

Trams beat buses in almost every way.

Passenger UX: - railed vehicles only move and accelerate longitudinally (with a little centripetal force at the very predictable corners). Consequences: people will often choose to stand even while there are free seats. Trams are so smooth that standing feels comfortable. (If you preference is to sit, you benefit too.)

- modern trams have lower floors than any road vehicle can realistically achieve (especially if built for use on random roads). They're near flush with the curb at tram stops, which is nice for accessibility (prams, wheelchairs, people with granny-trolleys for shopping).

Pedestrian UX: - trams follow tram paths, predictably. Once you're used to them (which doesn't take long), you'll stand just centimeters from a passing tram and feel completely comfortable about it. As a pedestrian, no transit line is as easy to cross as a tram line. (Certainly not a bus lane!)

Land use: - since trams follow rails without any lateral deviation or wiggle (and bonus: they're rather narrow), dedicated tram lines require about 40% less land than bus lanes. Especially on streets where there might not be much free lane width to spare, that counts!

Tiny operating costs, negligible marginal costs: - there's a far higher ratio of passengers to driver in a tram - electricity over wire makes the marginal cost of energy to operate negligible. Once the infrastructure is there, and once the tram is running, the frequency of service can be increased and the operating cost can get arbitrarily cheap.

Transit capacity: - road intersections are the capacity bottleneck in any road grid. Behind them, queues form and grow (congestion) until a point where the expected time (much of it queuing in traffic) presents too high a cost for the marginal journey to happen. - trams can pass at same gauge while scaling up intersection capacity by about two orders of magnitude, allowing much more rapid movement of people with much less urban land and less infrastructure

(buses with dedicated lanes could hypothetically deliver this, if buses were as popular as trams and operated like trams in dedicated lanes)

Air pollution: - the primary source of most urban air pollution is road vehicle abrasion (tyres on roads, brake dust) and road vehicle combustion engines. Getting rid of combustion engines solves less than half that problem. To stop primary emission of particulates, you need to solve tyres and car brakes. Railed vehicles do that: clean air. - a large part of air pollution is secondary: particulates settle on the large road surfaces comprising much of our cities. Then road vehicles with large tyre surface area (and varying lateral positions) run over the surface, re-ejecting that dust up into the air.

That air pollution is killing people (estimates vary: somewhere from 'many months' to 'a few years' of life expectancy are lost to urban air pollution). Trams get rid of it completely.

___

The biggest problem with trams is that they require competent civic administration, with a steady pace of long term infrastructure investment (boom & bust would destroys the capacity to produce & maintain trams & infrastructure economically), financed at competitive rates. They also benefit from very high urban walkability in the vicinity of potential tram stops, and high density of development (including housing). Not many cities have that.

Some cities do, and their trams are a dream: https://www.youtube.com/watch?v=t4Ph-L4Mbt4

Buses are considerably faster than walking, no? Eg 8 to 9mph or about 13kph in London on average[0].

I also observe that this is an average speed, which night be useful for statistical summarization but is not as useful as knowing whether the portion of the route that you want to take is in the faster part or the slower part of the data readings.

For example, if I took a bus from Aldwych up Holborn to Euston I might expect that the first mile would indeed be walking pace but the second mile I would be zipping along. It's important as a bus rider to not let the slow parts color your perception of the whole ride.

[0] https://www.london.gov.uk/who-we-are/what-london-assembly-do...

My data point: in NYC, the crosstown bus on 125th is noticeably slower than walking.

I usually take the tube in London but there are some point to points where bus is clearly faster than tube connections would be and absolutely faster than walking. Don't really know Manhattan up that far but crosstown tends to be slow in general.

Currently Apple Maps tells me great ormand street to Covent Garden is 19 minutes by bus and 21 to walk.

British museum to Shakespeare’s globe is 32 minutes plus up to 8 minutes waiting for the bus if there’s no delays. 40 minutes to walk.

Usually I walk or tube. There are just some point to points where the tube is a really awkward connection--e.g. Trafalgar to Shoreditch.

Whenever I've taken a bus in London it tends to be in zone 1. Between the walking to the right stop, waiting for the bus, the traffic, then walking at the far end, it's rarely quicker than walking.

Last week for example I took a bus from near St Pauls to Trafalgar Square, the entire jouney took about half an hour for 1.5 miles.

>A rail solution allows you to read, a bus throws you around everywhere and makes you sick.

I got exactly the opposite impression the first time I rode a tram in my life. The tram is really really shaky and the connection with the overhead line is flaky, leading to all sorts of strange noises.

I wonder which tram that was?

My experience has been the opposite: every vehicle on rails has offered a superior ride quality to every vehicle on rubber tires. I can't read on a bus, but on a train it's no problem.

Must be Romania...

https://www.youtube.com/shorts/BmoybIi8jIQ

It's very regional.

Buses meant for right-hand drive markets like the UK, Australia and Japan are (with very few exceptions) shaky, low-entry configuration two door junk, or double-decker one door junk.

If that's what you're used to, even the most rickety light rail system will feel luxurious by comparison.

Left-hand drive low-floor buses with three doors, and articulated models with four doors, which are intended for the European market, are as a general rule much more comfortable. If the buses you normally take fit the latter description, you'll probably find the average tram worse.

Buses also put a lot of weight on the road surface. Even more if you fill the bus with batteries. If you can reduce road surface wear at a cost of an upfront investment in installing these rails that could be a good trade off.

This is such a typical American sneer at public transport.

It's tiny, how it possibly carry all those 2x4s, powertools and sheets of plywood when I'm out doing manly things. I'd better go buy that monster truck so I can look like a real man.

In many non-North American cities one needs tiny. Big stuff just does not fit.

A normal public transit bus has twice the seats and doesn't need rails.

Yes and no.

Yes, this is smaller than the double-deckers in Coventry, that you can even do an eyeball comparison with if you watch the ironic publicity video mentioned in https://news.ycombinator.com/item?id=44217231 and keep your eyes peeled for the buses queued up at those temporary traffic lights in the background.

No, it's roughly on a par with the single-deckers, though, and there are quite a lot of those used by the local bus operators.

In the US a bus is a strictly worse version of the private car. Walking/biking/rail are effectively category differences so they don’t compete on the same playing field as a car and bus will. It’s very important for public transportation officials in particular to understand this, because not understanding it will continue the car-only suburban development until we run out of money and economic physics dictates how we do transportation but with insane costs in the meanwhile.

I guess you don’t need much space to dip your baguette in a cuppa tea

Amusingly for this stereotyping, the demonstrator that they have constructed has a Burger King a short walk to the south and two Chinese restaurants and one Indian a short walk to the north. (-:

This is a) an unnecessary counter-sneer at two whole continents and b) dismissive of something that would be a real problem in a city bigger than Coventry.

Those teeny tiny little carriages have a capacity a quarter of what the trams in my city provide. If one of them pulled up in peak hour here, I imagine it would fill up after two stops and be a nuisance from there on.

Trams can share lanes with normal car traffic. There's still a massive cost in terms of infrastructure (especially the overhead lines, utilities that need to get out of the way for the rail base, that sort of thing), but this project has a detailed description of why those aren't a problem for this project.

The tram they show in the animation also very much has a driver in the front.

If they can deliver on what they show in their demos, I don't see why the size of the trams or the infrastructure should be a problem. All the expensive stuff has been thought about, the system barely takes up any extra space, and the system is capable of scaling up by just sending more vehicles into service.

Generally I'm in favour of this sort of project, but having lived in Coventry (albeit a while ago) I'm a little sceptical: it's basically just adding a lot of infrastructure cost to what were low frequency suburban bus routes (the actual centre of Coventry is compact and walkable). You can run regular buses with similar capacity on batteries too, and divert them more easily.

See https://news.ycombinator.com/item?id=44217164 . Coventry actually does, right now, run quite an extensive network of electric regular buses, not only out of Pool Meadow but also the ones that circle the Trinity Street/Burges loop. And they had to divert them to build the demonstrator track for this.

Buses have slightly lower capex but much higher opex from the perspective of the community. City street gets ripped up by buses, cyclists get caught under the bus and dragged for miles, children get asthma from the tire dust. It being easier to give trams priority at traffic lights and easier to make the tram autonomous are just added bonuses.

Lower flexibility is actually a feature when it comes to mass transit: People will build density along rail lines because they assume the town won't rip them up, making the rail line more valuable over time. A bus route can be cancelled the day after a disruptive mayor is voted into office.

I also don't see why you can't scale up the tram with additional cars, as long as you keep the lbs/sqft the same. 3 car trams are fine, 3 car busses are... not

Also higher OPEX from the operator's point of view - trams can carry a lot more passengers per driver, they're more efficient energy-wise, and the replacement cost for bus tyres is large compared to steel wheels that last way longer.

Interestingly in this case the tram fits far fewer people than a typical British bus. A modern London route master fits a maximum of 87 people (standing and seated). This tram only fits 50 (standing and seated). I'm nonetheless certain that it will be a much nicer way to travel, but I'm not sure that the maths work out the way you might initially expect.

Definitely the high points of the story. And to emphasize — 15m corner radius!

Toronto has 11m loops. Newark 10m. Boston had 10m until a few years ago. This used to not be a problem anywhere.

It’s fairly obviously designed to avoid the issues which almost caused the cancellation of the new Edinburgh tram — spiralling costs caused by the need to move existing utilities under the deep track base. That crisis was probably as much to do with a badly formed set of contracts as with the technical issues themselves, but it’s still worth designing out.

Contracts that lock in a waterfall process.

At last they were not trying to use agile!

I do wonder how much of the backlash against agile is driven by people who never experienced waterfall

The key issue appears to be how long it took to realize that existing infrastructure would present a showstopping cost. In practice, waterfall and agile are virtually indistinguishable in their ability to anticipate such issues early - they can, but doing so depends on factors independent of the differences in methodology.

Either one of fine as long as you are doing it and not having it done to you. In the latter case, waterfall will crush your soul under a stack of binders, while agile is death by a thousand cuts.

That’s a really excellent insight! I’m going to use that!

Another common pitfall seems to be engineering teams choosing agile when the business engagement model is waterfall. This puts you in the unfortunate situation of trying to change requirements without being able to get paid for those changes.

Or who only experienced waterfall, which was always branded as agile.

I do wonder how much of the hate on “waterfall” is perpetuated by folks that never read the paper. It’s the “socialism” of development workflows…

Yeah, I was just being cheeky because I was trying to imagine software development models applied to large planned infrastructure.

A nuclear power station built successfully using an Agile process would be something I'd like to read about.

Avoiding relocating utilities is only really a stopgap until the utilities reach end of life at which point you would be ripping up the newly installed trackbed during the middle of its life.

At least in the US utility relocation also generally involves moving what was underneath to the side, so it can be accessed without disrupting the new transit line.

You can leave what's there and run new ones.

A 15 meter turning radius is tight, but not revolutionary. San Francisco's MUNI system's tightest turns are 45 feet, or 13.7 meters. The newer vehicles are designed for that, and the old PCC cars had to be modified to allow the trucks some extra rotation. The turning loop on Embarcadero near Market is that tight. There is much wheel screeching when a PCC car goes through that loop, because wheels have to slip to turn that tight. But it works.[1]

Battery powered trams have real potential, now that batteries with 5 to 7 minute charging and large numbers of charging cycles are a thing. That's compatible with typical end of line holding times. Steel wheel on steel rail is low friction, and you get most of the energy used to go uphill back when you go downhill. This could work out.

[1] https://youtu.be/XKN0MTCUSV0?t=265

> Steel wheel on steel rail is low friction, and you get most of the energy used to go uphill back when you go downhill.

If you were going up and down hills, would you still use steel wheel in steel rail unless you had some sort of cable to work with? I always thought the Muni did relatively level routes for that reason? The Lausanne m2 for example uses rubber (well, ideally you’d be able to just balance the train going up with the train going down, but that only works for simple inclines with limited stops). Actually, a battery powered rubber wheeled tram service on some sort of steep incline like SF’s cable car routes could get some wicked regen going down.

Even if level, they could still get some regen from making stops.

Problem with rubber wheels in metros is absolutely atrocious air quality. I avoid them like the plague.

How many rubber wheel metros exist? I only know of a few -- Paris is one, but not all lines. Where do you live such you need to "avoid them like the plague"?

Lyon.

Its not hard to find out where they are, Michelin is quite proud of them.

Montreal uses rubber tires in the underground. Never bothered me.

Fine particulates don't 'bother' you until you have that lung cancer diagnosis.

> Fine particulates don't 'bother' you until you have that lung cancer diagnosis.

Care to point out a source that supports a hypothetical link between rubber wheels and lung cancer?

Hypothetical you ask for?

https://pmc.ncbi.nlm.nih.gov/articles/PMC1757501/

To preempt accusations that the automotive endproduct isn't represented by this study, I'll concede it's next to impossible to have conclusive studies on specific forms of road pollution, that is, the best one can do is find a link between (rail)cars and cancer but nothing more specific than that :)

--Until they replace rubber in wheels with something else, I guess. Meanwhile, feel free to accept the reindustrialization

Tires contain carcinogens. That's not purely hypothetical, it has been known for a while.

The extent of impact is still being investigated, but we've known there is a carcinogenic link since before 2000.

[0] https://pmc.ncbi.nlm.nih.gov/articles/PMC6947500/

About OP: I swear, there is a HN "rule": When there is any opportunity to discuss health scare conspiracy theories, someone will pop into the convo (wearing a tin foil hat, naturally) to add their two cents. It is the perfect embodiment of Brandolini's law.

    > The amount of energy needed to refute bullshit is an order of magnitude bigger than that needed to produce it.

As a counterpoint to "avoiding rubber tyred metro lines like the plague": Does this person also avoid all road tunnels or expressways underground? Since there are frequently multiple lanes in each direction, that would mean much more fine rubber particulates from car & truck tyres compared to a metro with much less frequent trains and only one track in each direction.

I wonder if there's every been a study if the air quality in the montreal metro vs comparable cities. Or even within Montreal... does the blue line use tires? (Edit, yes, for some reason I thought one line didn't have them, apparently they all do)

I was told the tires are to reduce noise but I wonder if part of it is to handle some of the steeper sections like Vendome up to Villa Maria.

https://en.wikipedia.org/wiki/Rubber-tyred_metro#List_of_sys...

What's the problem? Rubber dust? Rubber smell? Maybe even burning rubber smell?

Also you have to replace tyres all the time, steel wheels last longer between services and are reconditioned on a lathe periodically instead of having to be continually replaced. It's one of several reasons why the longer term operating cost is way lower for trams than buses.

> would you still use steel wheel in steel rail unless you had some sort of cable to work with?

A rack rail is also an option, though tends towards the noisy and slow.

But yeah usually light rail keeps under 5%, and can’t really go above 10 on pure adhesion.

The J Church line on Muni is still a train in part because back when they were converting lines to buses, the hill on Church St was too steep for buses.

Wiki says it was more because of the private right away used, not necessarily its steepness:

> While many streetcar lines were converted to bus lines after World War II, the J Church avoided this due to the private right-of-way it uses to climb the steepest grades on Church Street, between 18th Street and 22nd Street.[9]

https://en.wikipedia.org/wiki/J_Church

> Ironically, this steep grade saved the J-Church line from being replaced by buses. After World War II, San Francisco began replacing the streetcar lines with buses, but the Church Street hill proved too steep.

Little bit of columns A and B

https://www.opensfhistory.org/osfhcrucible/2019/08/10/the-j-...

muni has "relatively level routes" because the routes that were preserved were ones with tunnels that buses couldn't fit through (or narrow ROW in the case of the J), and given sf geography those tunnels invariably go through hills. muni, and especially the J, is one of the steeper adhesion railways in the world

Modern speed control technology has expanded the incline range for steel-wheeled trains quite a bit. Inclines that would have historically pointed towards rubber-tired or non-traction systems are usually within the range of steel wheels with solid-state motor control. Basically the control of torque is much finer than in old resistance-box parallel/series speed controllers, so you can avoid slippage much more easily.

If the vehicle is battery operated there is no longer a need to use metal wheels. Something like ABS, nylon or rubber probably results in less wear and noise. (Perhaps at the cost of a bit more dust from braking though)

Metal wheels have significantly reduced friction, switching to something like a car tire would require much more frequent tire replacements and would have a lot more issues. Steel on steel is the way to go for fixed-route vehicles if possible.

Maintaining a quiet operation is listed as one of the advantages of the turning system for this system.

> A 15 meter turning radius is tight, but not revolutionary. San Francisco's MUNI system's tightest turns are 45 feet, or 13.7 meters.

Revolutionary as the turning circle will be used at speed with passengers to traverse roundabouts in-lane. CVLR doesn't need turning loops, as the vehicles can be driven from either end.

Overhead power is more efficient and sustainable though. No batteries to chug along, no batteries to replace or manufacture. And I wonder if the cost over time really makes up for hanging a few overhead lines.

Several North American older systems go down to 10-11 meters, although perhaps the tightest curves are getting upgraded over time:

LRT systems on which the existing minimum curve radius falls below 15 meters include:

• Boston—10 m (33 ft) and 13 m (43 ft) for the Green and Mattapan lines, respectively;

• Newark—10 m (33 ft);

• San Francisco—13 m (43 ft); and

• Toronto—11 m (36 ft).

https://onlinepubs.trb.org/Onlinepubs/tcrp/tcrp_rpt_02.pdf (1995)

Heavy and Light Rail in the UK is also a safety distinction: Light Rail is limited in speed, drives on sight (exceptions apply) and a few other restrictions (https://www.orr.gov.uk/about/who-we-work-with/railway-networ...).

Trams are one example of Light Rail, but so is the Docklands Light Railway in London (an exception to "on sight" - it's automatic), as opposed the the Tube (underground) which is Heavy. But the Welsh "metro" project's "tram-trains" (Stadler Citylink) are also Light, even though their tracks into the valleys are very much not urban in the usual sense - the full valleys journeys are over one hour with the current trains and go through mostly rural areas with small towns.

Why is it easier for cities to develop obsolete stuff than to eg, run their own Uber?

Uber and mass transit are an apples and oranges comparison.

What's the highest capacity vehicle Uber has ever operated? Because Tranist can move thousands of people with a single operator

In the whole universe of intellectually honest, valuable benchmarks for transportation, do you think ride sharing wins on zero?

I’ll give you an important one as an example: door to door journey times. I support RTO, which is the best way to improve that metric for the average person, which is to say, I was hoping this would be a discussion for out of the box thinking. Or really, what do you invest millions of infrastructure bucks into? All of Uber was only a little more expensive than a single high speed rail line. Why can’t cities run ride share? Why would they run ride share worse than a train service?

> All of Uber was only a little more expensive than a single high speed rail line.

And charges/charges more for the service rendered, and still makes a loss.

And if the city would charge for the taxi service... Why run it when other operators can and do? And multiple operators can effectively compete.

> All of Uber was only a little more expensive than a single high speed rail line

Sure, if you don't count the vehicles and the roads – the actual _transportation_ bit

Door-to-door time is going to severely suffer on Uber if (and cars in general) are the only option in dense cities. They'll spend most of their time sitting in traffic.

Once you reach a certian density, cars just take up too much space on the road for the number of people they carry, and the only way to meaninfully reduce traffic congestion is to take people out of cars and onto higher-capacity transit.

We already know ride-sharing can't scale up unless your city has super low population density.

If you want a real tram that is compatible with existing street geometries, the really nice Škoda ForCity Smart Artic tram was developed to meet the requirements in Helsinki, which wanted a smooth modern tram even though there are 15m radius curves and 8% inclines in the old parts of the network. https://en.wikipedia.org/wiki/%C5%A0koda_Artic

Eliminating "the need" for overhead wires seems like a terrible trade off when you're adding "the need" for expensive batteries and charging infrastructure.

Overhead wires are not trivial. Charging is.

You're very wrong about that.

Charging is just a point. Cables must be over entire track system. And if you at any point in time decide that cables are more economical you can always put them over any part of the track where you think it makes economic sense and use them to charge. If we had lithium batteries first there's be scarcely any overhead cables anywhere.

Heck, in US they don't even bother with cables or batteries, just put a diesel generator and a tank on electric trains for decades now.

But if you still believe I'm very wrong, please do elaborate.

Besançon in France is one of the cheapest conventional tram schemes in Europe at €17.5m per km and €1.81 per tram (132 passengers). It’s a conventional tram track with overhead catenary wires: as standard as one can get with those things. Presumably in the UK the costs would be somewhat higher: France is a modern tram capital, with a lot of relevant talent and expertise available locally.

I haven’t found the projected figures for Coventry but it would be very, very awkward if they can’t beat the numbers above with a supposedly much cheaper track.

https://en.wikipedia.org/wiki/Trams_in_Besan%C3%A7on?wprov=s...

CVLR is projected to cost £10 MM per km, but we all know what projections are worth.

Still, there's no point comparing build costs between France and the UK as they're completely different cultures and jurisdictions. Instead, a more reasonable approach is to compare to recent similar project in the UK.

Edinburgh's tram covers 18.5 km and cost at least (they're still uncovering overruns years later) £1 BN. That's ~£50 MM or ~€60 MM per km. That's what CVLR should and will be benchmarked against.

Very good point. There’s also a potential for future upgrades. They may invest into catenary lines at some point, get rid of batteries and increase capacity inside vehicles. Or, switch to hot-swap batteries and increase vehicle turnaround and frequency. Or, they can switch to traditional concrete reinforcement for rails for future lines if they decide that the rails-on-slabs approach doesn’t work out as well as they hoped for. Their vehicles while custom-built are running on top of standard tram lanes, so they will be able to use traditional tram tracks, too.

VLRT seems gimmicky at first but the more I look at it the more sense it makes.

> they're completely different cultures and jurisdictions

Separated by huge distance of 20 miles, both have thousands of same EU laws )still on the books, share thousands of years of history and at one point ruled by the same aristocracy.

Okay, but still completely unhelpful to judge per km costs in one versus the other due to the enormously different political and legislative environment.

If they enormously different, what are you going to call South Korea, Armenia, China? I mean is anything comparable?

The real point I was trying to make is that they achieve similar outcomes, in passenger safety comfort.

And if we really do believe that legislation is so different, then is there any point of arguing about an innovation in the physical parameters of the system, after all you can only make a tram 20% lighter, but you can make the legislation 300% worse or 300% better

True. And yet, they are completely different cultures and jurisdictions.

There are lots of national laws outside EU laws. For example, in France, compulsory purchase of private land by the state (to do things like build new railway lines) has to be 1.5 times its value, the idea being that this only happens when they really want to do it.

Manchester's Metrolink should also be used as a benchmark.

The Airport line extension cost £368m with 15 stops over 14.5km of track (which shakes out at roughly £25m/km), and was completed more than a year ahead of schedule and under budget.

That line is really slow, it can be faster to get to the airport by getting the tram to East Didsbury then changing to a train.

Well it depends on where you're trying to go.

As a means to get to the airport from the city centre? Yeah, heavy rail is probably better.

But that's not the only reason for the line. It's used to get to and from other points on the route too.

As a means to get to the airport from almost anywhere, heavy rail can be quicker. TBF, the route planner on the TFGM website will tell you if this is true and tram tickets to the airport are valid on the train.

The Airport Line might be better labelled as the Wythenshawe Line.

If only there was some sort of mechanism to easily enable talent sharing between the UK and the rest of Europe.

This is a great look at why UK infrastructure is so expensive: https://www.samdumitriu.com/p/britains-infrastructure-is-too...

TLDR: Because they always try to do innovative things rather than just copy tried-and-tested methods from other countries.

Everything old is new again: The Light Railways Act of 1896 also propsed rail lines built to less then mainline standards (often narrow gauge) to get transport links to otherwise unconnected locations. https://en.wikipedia.org/wiki/Light_Railways_Act_1896 comment edited because I fat finger editing the submit button

As this page notes: https://www.coventry.gov.uk/coventry-light-rail/coventry-lig...

They're using "Standard rail components, innovative construction" - standard gauge rail, but laid over a foundation of slab ultra-high performance concrete (UHPC), which allows for the shallower foundation / avoidance of utilities relocation.

Using UHPC to rethink infrastructure is the big story here, I think.

> The vehicle has a capacity of 56, is comfortable and has low floors to enable passengers to embark and disembark easily

That's a _very_ small tram, smaller than most buses.

I assume 56 is the capacity that they advertise but people will cram in like sardines when it’s rush hour

The buses around here advertise a capacity of 90, and the trams a capacity of 400.

It's not smaller than most of the buses that run in the existing Stagecoach and National Express fleets that go around and to and from Coventry, which seat approximately 30 people on a single-decker with standing room for about 10 more (in the best case, with no push-chairs, trolleys, or wheelchairs).

Important background: Building the same tram in Britain costs at least 2X more than in France, often 3x more.

UK tram track construction typically involves deeper track beds compared to France/EU, using concrete slabs of 500-1000mm deep, is intended to protect utilities. In contrast, many European projects utilize shallower trackbeds, even with grassed areas, which are 300-400mm deep

Does the UK have a loose, silty soil which requires the deeper track beds or more stringent safety regulations or something?

Gadgetbahn - a derisive term transit advocates use for something that claims to be innovative but in fact doesn't do anything not thought of before and doesn't solve any problems.

They make all kinds of claims that don't stand up to over 100 years of history running trains. The claim they are innovative, but there is nothing new here, and no evidence they have looked at the real problems of transit systems. Someone is going to make a lot of money on this at the expense of the community that loses.

Trains have been around for a long time. You can buy all the parts you need for a good system off the shelf. You won't be saving money by designing something new, you just waste money on engineers to design something and then lose the scale factors you could get from buying the same thing as everyone else. If you buy the same thing as everyone else that means there will be a market for spare parts and thus in 20 years when (not if!) something breaks you can keep the system running.

Yes overhead wires are expensive - but they are a rounding error compared to track. Batteries are expensive too, and you have to buy a lot of them. Batteries need to be recharged which means these trams will be out of service often so they have to buy a lot more so that when one is out of service for charging the others can work. (you still need a few extra for maintenance, but battery charging is more common so you need a lot more)

If you want to build a train the best way to save money is to build exactly the same as everyone else does: standard off the shelf trains, running on standard off the shelf rails, and standard off the shelf overhead rail. If you want to innovate make sure that everyone is fluent in Spanish, Turkish, Korean, or Italian - because places where those languages are spoke build and run trains much cheaper than other places you can think of so you want to learn from them. (note that French or Japanese are not on the above list - while those areas do cheaper than English speakers, they are still expensive)

I'm not sure about the UK, but in the US most of the cost blowout for trains seems to be in stations, so focus all your innovation there: don't make them monuments to how much money you can spend. (The UK has cost problems almost as bad as the US, but I'm not aware of any study on where the issues come from, while at least in the US there are studies).

You’re grossly oversimplifying and ignoring knock on effects.

Eliminating overhead wires isn’t about cost. It’s about being able to build in existing urban areas that don’t want high voltage live wires everywhere, and likely already have above ground infrastructure they would interfere with.

Well the standard response to this kind of "do it the way everyone does it" is "... change has to start somewhere". It's hard to tell, without hearing a report from a council of open-minded-rigorous-experts, whether some claimed innovation on a particular is actually worth doing or not---but certainly neither of "innovation is always good" and "innovation never works" is true.

Anyway everyone is pretty sure that that something is wrong with the standard train economics as you describe them, because if there wasn't something wrong with it there'd be a lot more trains. I can't tell from the site, or from your comment, if this is the solution, or even worth doing as an experiment... but "don't change anything ever" doesn't strike me as productive either.

The problems with trains are well known and they are not addressing them. There might be unknown problems an well, but the things they are talking about have already been tried and failed for reasons they don't seem to be aware of.

Innovation should require some knowlegde of what is already done - otherwise you invent square wheels.

They're addressing one problem, and one problem only.

Adding a bus line isn't sexy, even bus rapid transit (BRT) sounds like a wet fart. They work, they can work extremely well, but nobody gets excited about it.

This thing is just like a monorail; something worse than a bus but that sounds sexier.

Interestingly, in public policy, how sexy something sounds tends to be directly proportional to how much the public is willing to spend. It's often easier to get 10-100x the money of a bus for a rail link.

CVRT is proposed to replace existing BRT for cost, environmental, and safety reasons.

What is CVRT? I'm getting "Combat Vehicle Reconnaissance (Tracked)" and though that sounds like it would be cheaper, more environmentally friendly, and safer than a bus ;) I doubt it's what you're talking about.

Hah, I used to work with a CVRT squadron (Scorpions) back in the day, so I think it was muscle memory. It should read CVLR - my apologies!

They are addressing the problem of cost by 1) using BEVs to reduce overhead wire cost, 2) using tighter turn radii to reduce retrofitting needs, and 3) reducing the depth needed to avoid costly subservice infrastructure disruption

There is no evidence that wires are expensive. There is evidence that wires are cheaper if you are running frequent service.

> There is evidence that wires are cheaper if you are running frequent service.

Given the rapid progress in battery and battery charging tech, I doubt that evidence still applies today.

Also, they may be cheaper in the long run but require more up-front investment. Depending on the interest rate, that can swing the answer to the ”what’s cheaper?” question

You’re talking about trains, but this is about trams. The design constraints of building into an existing and very dense road network are complex.

I agree with much of your sentiment, and hope that the Coventry council is being challenged in these sorts of ways, but at the same time I recognise that each city is going to have quite different requirements for trams driving down the roads in its centre.

Perhaps a better push back is: why isn’t this just a better bus network?

A tram and train are the same thing. No difference at all.

There are different modes of operation that differentiate them but fundamentaly they are all trains and face the same issues

They operate in completely different scenarios. They’re the same shape, but they’re a different set of hardware, constraints, accessibility, need to be scheduled in a different way to account for traffic, different safety concerns, different signalling systems, different distances, different surroundings.

Again I sorta see what you mean, but feel you’re massively over simplifying this.

I mean trams basically are street-running trains. The light rail/heavy rail distinction is more one of weight and size than actual issues.

Ceci n'est pas une tram: https://www.youtube.com/shorts/kMUANU9H6aw

https://en.wikipedia.org/wiki/Rubber-tyred_metro and https://en.wikipedia.org/wiki/Guided_bus also exist.

(For me, the big thing about trams and trains and subways, etc is that the track is a kind of social construct - the track tells me that eventually a vehicle will come for me - no need to really worry about timetables, etc. A bus, a bus may come, maybe it won't. It's all psychoillogical but it's there the same.)

The fundamental operational principle is different. Trams operate (typically, on street running sections) on sight - they are responsible for monitoring traffic, and stoping if necessary. Contrast with the block-based approach used for trains, especially in combination with Euro-style positive train control systems.

A tram is just a bus running on smaller, steel, roads.

Maybe another analogy:

A tram is a golf cart or ATV A train is a highway bus

They have different applications and contexts in which they operate, even if they have core similarities

Your comment contradicts itself.

The second sentence is partially true: they do have different modes of operation.

But no, they don’t face entirely the same issues. Trains should hopefully never routinely encounter cars sharing their track and they don’t have to make tight turns to follow existing roadways.

Modern European trams are increasingly grade-separated. See what Marco Chitti has to say about European road design.

Well then there's no difference between overground and underground trains. But it's pretty clear that there are different issues facing building new metro lines.

Unfortunately the Coventry VLRT is all about aesthetics over actually transit benefits. If the they were concerned about being useful transit the vehicle would have capacity higher than an articulated bus. Instead the main benefit of Trams/LRT over buses, capacity, is sacrificed leaving no real benefits. You can see the same thing with the Obama ere streetcars in the USA where most of them proved no real benefits over the buses the run alongside them but at least they retained the capacity even if it was never needed.

London’s DLR is a gadgetbahn. For all its obvious limitations it’s been quite successful. Lots of new stations, lots of expansions, decent integration with traditional rail. VLR would work similarly.

I don't think it's gadgetbahn

>something that claims to be innovative but in fact doesn't do anything not thought of before and doesn't solve any problems

The DLR was I think about the first decent scale autonomous rail system and provides a lot of transport.

I mean things like https://en.wikipedia.org/wiki/Morgantown_Personal_Rapid_Tran... predated it by a decade but is dinky in comparison.

Kobe’s Port Island Line is generally considered the first fully automated metro and opened in 1981. Lille Metro is about the same scale as the DLR and opened in 1983.

Finding the right balance of capacity is a tough problem because cities generally intend to grow, and it's expensive to to have unused capacity. As well if you actually build for that, people will say the project is a failure since ridership will seem low.

These shelves must be huge!

In Australia, highest cost is buying up required land and construction of buildings. We spent ~100mil USD on a single, open air platform for a line extension of exactly that one station. It was about 5 km of extra track. It is amazing we have any trains at all.

> If you want to build a train the best way to save money is to build exactly the same as everyone else does: standard off the shelf trains, running on standard off the shelf rails, and standard off the shelf overhead rail.

You are speaking like a naive person that thinks that most the challenge is the physical world

But in UK most of the challenge is archaic and idiosyncratic laws, disproportionately powerful NIMBY’s and the treasury brain.

The treasury brain will approve a project with 1X capex and 10x opex instead of one that has 2X capex and 1X opex

The NYMBY is wild and unpredictable, they just killed project for a data centre placed on top of a literal dump because it would ruin the view of that dump from a motorway (nobody lives there)

A project to re-open 3 miles of railway that already exists took 5 years to approve and 80,000 pages of environmental accessment

But if it’s innovate and designed in UK it might just slip through

Have I encountered a fellow Rail Natter enjoyer?

Never heard of him until now. Looks interesting but I don't have tine for anouther hour long podcast in my life... I suspect he is drawing on similer sources as me - there are many other transit advocates saying what I am in greater detail.

Ah yeah it's likely he's distilling various ideas that are often discussed within the rail/transport industry in a form suitable for a more casual audience

If it is battery powered why does it need rails? Why not just use an electric bus?

There's various possible reasons. Less pollution from tire wear and the possibility to lay tracks across grass to create relatively ecological dedicated lines so the carriages don't get stuck in traffic are two options that spring to mind immediately.

Efficiency — mainly through lower friction

“Thanks to the very low friction between the steel wheel and steel rail, railways can move a load using as little as 15% of the energy that road haulage needs.”

Gareth Dennis, How Railways will Fix the Future (https://www.penguinrandomhouse.com/books/761930/how-the-rail...)

Everyone proposing trams says this. None of them provide any numbers. How much more efficient does it have to be to offset the much greater cost of the roadway?

If overhead wires were the only advantage of light rail, why is anyone using light rail instead of trolleybuses?

The answer is of course that rails provide major advantages on their own, primarily by allowing vehicles to travel much more efficiently thanks to the low friction of running steel wheels on steel tracks

They also provide major disadvantages, like a single obstacle or broken down vehicle blocking the entire route.

BEVs will become more popular (in my prediction) because they are simpler than diesel, and are self-contained unlike electric trains that depend on external wire systems working, so they will be more reliable.

It does make the name kinda ironic, since the batteries will make the tram heavier then a normal one that's powered by overhead wires, so its not 'very light'

What advantages are there over bus service?

Trains have their own right of way, buses sit in traffic.

Modern urban light rail is also typically electric, using overhead power. Although buses can also use this.

This is one of the main reasons the super dense Japanese cities aren't as air poluted as other urban centers.

You can have a bus-only lane easier than a tram-only track.

A bus only lane is also a vehicle lane that is sitting empty a good part of the time.

Not really that efficient...

And, as has been rediscovered about 200 times in Southern California (by the drivers, not by the sstate government), you can add additional lanes almost indefinitely, and it doesn't really help congestion that much.

> A bus only lane is also a vehicle lane that is sitting empty a good part of the time.

You can make the same argument (in terms of space) about a train track. The real advantage of trains (light or heavy) is permanence. It's easy for the next government to remove the bus lanes because "OMG too much traffic, one more lane will fix it." It's much more difficult to rip out a rail line and convert it to a road.

> A bus only lane is also a vehicle lane that is sitting empty a good part of the time.

A rail track for the same route sits empty just as much.

> you can add additional lanes almost indefinitely, and it doesn't really help congestion that much.

I don't think adding bus-only lanes would have that effect. Adding lanes for private vehicles reduces congestion, which encourages people to move to places along the route until the congestion reaches the previous barely-tolerable level (as I understand it).

This is one of these sets of information that don't seem to make sense until you fit it all together.

Busses aren't much more efficient when riding down a lane than lower occupancy vehicles, but streets aren't bottlenecked by their roads, they're bottlenecked by their intersections. The key advantage of a bus is at the intersection. A bus holds the intersection for far less time than the equivalent passenger capacity of cars.

The problem bus lanes try to solve is dominantly that without them the traffic advantage of people riding busses mostly goes to people not riding busses, and this makes for a pretty terrible incentive structure. Busses are intrinsically disadvantaged against cars (schedules, uncertainty, routes), so if you don't help them, then people will prefer to drive. Bus lanes internalize the externality.

> A bus only lane is also a vehicle lane that is sitting empty a good part of the time.

While that bus lane may look empty most of the time it likely carries far more people per hour than the congested car lane next to it.

> While the Lincoln Tunnel’s car lane can only move 3,000 people per hour in each car lane, its bus lane moves 30,000 people per hour.

https://transalt.org/blog/bus-commutes-are-significantly-lon...

I think you've been lied to with that highly misleading statistic. The 3000 for cars is actual (though I'm skeptical of that now too), while the 30,000 for buses is theoretical. "While a typical traffic lane carries approximately 3,000 people in 2,000 cars each hour, the XBL lane can carry over 30,000 people in 700 buses during that same time period." http://fourthplan.org/action/highway-congestion

That doesn't seem unreasonable for the Lincoln tunnel. Rush hour buses are pretty full, 50 on each seems pretty reasonable - everyone got a seat!

> Now the XBL handles 1,850 buses that carry more than 70,000 passengers from 6 a.m. to 10 a.m. each weekday, which comes to 600 buses an hour. The bus lane operates at its maximum capacity for 90 minutes of its four-hour operation.

https://www.govtech.com/transportation/fed-funds-study-of-ai...

Here in San Francisco along Mission St we have about 20 articulated buses an hour in each direction. These have a planning capacity of 94, 85% load standard 80, 125% crush capacity 119 according to https://www.reddit.com/r/AskSF/comments/445xdg/what_is_the_m....

While mostly a bus and taxi lane Mission St allows local traffic within each block so buses are still a minority of the vehicles in the lane.

Meanwhile the main 2 lanes in each direction street nearby has 1020 vehicles an hour in the peak direction. At 1.6 people per vehicle that's only about 830 people per lane at rush hour. So even at 'standard capacity' the buses in a regular city street not completely dedicated bus lane carry double the number of people. (From experience I suspect it is somewhat more than that.)

700 busses per hour is a BIT unreasonable.

That's a bus every 5.1 seconds. In a single lane. (and at 30mph it'll take 1.5 of that 5 seconds just for the bus itself to pass. That's very marginal braking distance).

Also, 1850 / 4 is 453, not 600.

> 700 busses per hour is a BIT unreasonable.

The article I quoted to which you are replying suggests 600 busses an hour. I don't think that is unreasonable for a dedicated highway lane into a bus terminal. There's a nice picture of it here: https://abc7ny.com/port-authority-lincoln-tunnel-technology-...

> Also, 1850 / 4 is 453, not 600.

Quoted in the post you are replying to:

I read that as they reach the maximum capacity of 600 buses an hour only for the 90 minutes of rush hour. Across the 4 hours it operates each bus averages 38 passengers (70000/1850). It seems reasonable to assume that the rush hour buses are more packed given they are looking at ways to increase capacity and have you ever taken a rush hour bus in a big city?!

From the picture linked above these seem to be 53 seat coaches for longer distance routes rather than city buses which would carry more passengers with some standing. 50 * 600 = 30,000. It's in the ballpark!

No less efficient than track sitting empty most the time.

And your bus only lane has a lot more options. If there is a major disaster you can divert other traffic (not necessarily all traffic though that is an option) into it which might be a useful compromise at time. If you need to repair your bus only lane you just divert the bus to regular traffic. For that matter most places there isn't any traffic and so a bus in mixed traffic has no downsides thus not costing you that whole lane (or track), just build the bus-only lane where it is needed.

Trains are a good thing when they do something a road cannot. However the common bus can be just as good for much less. If you have the money and want good service and ride quality the bus can do it too, and typically for much less cost than a train.

Trains are good where they don't mix with traffic (meaning elevated or underground) because they can then be automated (and also faster). Alternatively a train can hold more people, so if you are in the rare situation where a 100 passenger bus every 5 minutes can't handle the passengers a train is good. Most of the time though you are not in either situation and so a bus can do everything a train can.

> No less efficient than track sitting empty most the time

Unless the track is just in a regular lane that can be full of cars/busses/trucks whenever there isn’t a light train. Like how trams work in most of the world

I live in a city with trams in the UK and that’s not how it works. There are sections that run on dedicated train lines, and sections where it runs on the street. Where it runs on the streets, priority is given over cars by switching traffic lights to red. Once the tram has passed onto the road it switches back to green so you can end up following the tram in your car.

Don't measure vehicles per hour. Measure people per hour. Also letting the cars in means more people use cars means you soon need another lane.

Other advantages: people who don't drive, which includes children can get about. Lots of public transport can compensate alot for un walkability of suburbia.

Physically easier. Often not politically easier. Voters are often more willing to pay for a metro than lose a lane from cars. We ran into this in Seattle over and over.

Busses don't have to sit in traffic, but they can (and trams can too, in some cases)

Bus rapid transit, when done right (basically, almost like a tram) can be quite successful: https://www.youtube.com/watch?v=fh1IaVmu3Y8

When you have a cost overrun on BRT, the easiest way to save money is to share ROW with cars.

Since it's harder to make that choice when you're building rail, it's more likely to be done right.

no tire dust

One advantage is that light rail encourages transit oriented development.

The fact that buses are so flexible and easily (and cheaply) rerouted makes developers less likely to build developments that rely on access to transit, but once a community spends a hundreds of millions of dollars on a light rail line, they know it's there for the long term.

That's sad but I can see that. Maybe more with train and metro stations though than light rail that often makes little difference to commute times vs a bus.

I've seen that claim, but places that run good bus service for decades see plenty of transit oriented development. (most of those places also have subways though. The other options seems to bad bus service which won't get transit oriented development but bad service is enough to explain why)

As a city grows, it's common for the transit system to evolve from direct bus routes to trunk lines supported by local buses. Maybe there was a good bus service to the city center when you bought your home. But now the buses only go to the nearest transit hub, because there is no space for all the buses in the city center anymore. While the average quality of transit may have improved, your services are slower and less convenient than they used to be.

You and I are well aligned on a lot of things - but in general, buses do not result in TOD. There are some exceptions, but they are very much exceptional. Trains generally do result in TOD because the people pushing for TOD get to try over and over again.

That's sort of the popular wisdom, but rails don't guarantee it will be there for the long run. DC recently announced that they're replacing their light rail with buses:

https://www.washingtonpost.com/dc-md-va/2025/05/27/steetcar-...

Jarrett Walker has a good piece about it: https://humantransit.org/2025/05/what-was-wrong-with-the-was...

I agree with him that in order to endure and justify a permanent operating subsidy a transit service needs to be useful and used by many people. Most American light rail doesn't meet that bar.

Interesting piece, thanks. I also enjoyed his piece "Streetcars: An Inconvenient Truth." His argument is based on length, speed and cost; the main point is that a technically equivalent bus would often be cheaper and thus could be run on a longer, more useful route. If you look at the hundreds of millions spent on DC Streetcar and its limited utility, this all starts to look quite obvious. So why did we do it?

I think there is another aspect that usually goes unstated, which is the vibes. If you're a mayor you want to build a tram. If you're a tourist you want to ride a tram. If you're a prospective resident you want to live near a tram. Yes, it's smoother and yadda yadda, but really it's because it has more sex appeal. A technically equivalent bus may well be _technically_ equivalent but could never be truly equivalent. Nobody would write a play entitled A Technically Equivalent Bus Named Desire. In a way, spending money on a tram is similar to spending money on parks or flowers or public art. And so we will spend the money; and we will build the streetcar; and damn the technical equivalence.

I wonder what the world would be like if we were honest with ourselves.

I never heard of the (Washington, D.C.) DC Streetcar until this comment.

Wiki tells me:

    > The DC Streetcar is a surface streetcar network in Washington, D.C. that consists of a single line running 2.2 miles (3.5 km) in mixed traffic along H Street and Benning Road in the city's Northeast quadrant.

Is it even worth building a rail project that short? I had less than 900K riders last year. Something about light rail is so underwhelming to me.

There's been a ton of research on this and the conclusion has been that light rail does indeed attract more development than bus rapid transit, but that there is no net gain in development across an urban area. It just shifts development to the corridor in question. There's a reason the overwhelming majority of transportation engineers favor bus rapid transit. On the other hand, I personally prefer to ride in light rail and I think many people would agree. So there's a reason that many urban planners prefer light rail.

For me, trams have a much more comfortable ride. The lack of pitch and roll reduces a lot of motion sickness and the rails are obviously a lot smoother than paved surfaces.

There’s nothing stopping a road from being smooth but, logistically, there’s clearly no reason to rush to repair roads when they deteriorate. That means potholes get tolerated, potholes means suspension, and both of those mean bus-like rides instead of suburban light rail rides.

Railway track has to be flat. Anything less than perfect is intolerable so it tends to hold its maintainers to a higher bar.

As I understand it tracks do a much better job of spreading the load than asphalt which makes it much more durable.

I've found the new battery buses to be far more comfortable to ride in than older diesel buses since they remove the vibration when idling. The extra weight might mean more potholes to repair though.

What pitch and roll? And potholes in a road can be maintained at far lower cost than building railway lines.

And lastly badly maintained railway lines are just as prone to causing motion sickness as badly maintained roads.

Buses are just… bouncier!

You’re absolutely right about potholes, technically, but my point was more about how people work not the immediate technical difference between road and rail.

If you have a system that requires 100% upkeep in order to function at all — the rails of a tram system — then it receives nothing less than the complete maintenance it demands.

The social and technical economics of roads, on the other hand, practically ensures that they’re only ever barely maintained to the lowest possible standard people (and air suspension) will tolerate.

Trams, the divas that they are, will tolerate nothing less than perfection!

> they’re only ever barely maintained to the lowest possible standard people (and air suspension) will tolerate.

Perhaps that's true where you are but it is simply not true in large parts of northern Europe. I'll grant you that a lot of UK roads are a disgrace though

They’re much more energy efficient due to the lower friction

Try to transport the following objects - would you rather do it on a bus or tram?

a longtail ebike, a pushchair with/for 2 kids (horizontal arrangement), a dining table for 6 people and 30 kg of cement

I tried it, and with most of em they don’t let you on a bus or you can’t fit but tram is fine

The text display in front seems to be easily overpowered by sunlight. They could use a display that's also readable by daylight.

I guess they're aiming to handle narrow edge cases in later iterations.

They are designing for Coventry, UK so "sunlight" is an edge case.

Not really related, but leaving Coventry has probably been one of the best decisions I've made in my life. This makes sense though, one of the best things about the city is the good transport links for getting out of it.

Since there are going to be a lot of people who don't even know England, let alone Coventry:

Coventry is, like many cities in the U.K., burdened with road systems that in some places go back to mediæval times. Yes, the Nazis did famously bomb the city centre, but there are some parts of the mediæval city remaining, and much of the outskirts of the city is where it has expanded since World War 1 to swallow what once were standalone villages like Walsgrave and Stoke that dated back to the times of the Domesday Book. Much of the street systems are the old country roads through those villages, augmented by housing estates built around them. So Coventry does not have a wide and regular street system. There is no grid, Norteamericanos!

There are only a handful of dual carriageways for major arterials. Some of the rest is quite cramped, and the ring-road, an early experiment in U.K. post-WW2 reconstruction that basically taught the U.K. how not to build inner city ring-roads, is a massive barrier to any public transport system. The ring-road was some years back significantly re-built just to make the railway station better accessible, whose entrance is on the ring road.

Coventry is actually fairly well served with bus services, to and from nearby Warwickshire and Solihull, and within Coventry itself. There is a significant electric bus network already in place for some years, and Coventry has been more proactive in moving buses from diesel to electric than those other two have, although they too are gradually replacing the old diesels. Stand at the bus stands on Trinity Street in the city centre, and you'll see mostly electric buses go by.

The ironic thing of this project being placed where it is (aside from the amusing fact that the tram route is literally a route to nowhere, as Queen Victoria Road was blocked off in the mid-20th century when the ring road was constructed and is now a dead-end) is that to construct it they had to divert many of the bus services, since Greyfriars Road is one of the routes to and from the main city centre bus terminus.

Coventry has been quite experimental in recent years when it comes to transport design. Aside from hacking the ring road about, it has experimented with things like converting many of the street intersections around Coventry University (not to be confused with Warwick University, a partner in the headlined project) into shared space intersections.

Would this actually work as a general transport system in Coventry as whole? Almost certainly not. A light rail system from, say, the Coventry Arena to anywhere useful elsewhere in the city would bedevil Jimmy Hill Way. That's why there's a commercial centre right next to the Arena in the first place. In the outskirts of the city the Hipswell Highway and routes like St James Lane/Willenhall Lane and the Holyhead Road are major thoroughfares but some are already down to 1 lane wide in places. And the idea of running a tramway along Radford Road or the Foleshill Road is sheer lunacy to anyone who has seen those roads.

The scope of any tram system is almost certainly physically confined to the old city, and maybe the A4600 and A428. But the old city is actually walkable. The places where public transport is needed is the arterials like the Holyhead Road, already well served by buses. Cynically I expect that much of this is about selling this system to other cities.

And indeed, the partnership with Dudley Council is strongly indicative that this is mainly using Coventry as a staging area for development that will be, if it takes off, more in the rest of the West Midlands than in Coventry itself. There is, physically, more scope for this sort of thing in the road systems of Walsall, Wolverhampton, Dudley, West Bromwich, Wednesbury, Great Barr, et al. than there is in Coventry. I wouldn't be surprised if at least one councillor is being sold the line that this is really to sell it to other cities around the world.

Addendum: If you watch the latest news video and ignore the local politician trying to sell the scheme in the foreground, in the background you can see the actual public transport services in Coventry, the double-decker buses that run along Greyfriars Road, stopped at a temporary set of traffic lights put up to accommodate this demonstrator, as Greyfriars is now a single lane running half-duplex where it used to be two lanes running the buses full-duplex. Many of the bus routes out of the city to the south come in to the city centre along this road. Yes, this is ironic.

* https://coventry.gov.uk/news/article/5276/first-ride-on-vlr-...

I wouldn't be planning any fixes infrastructure transit programs that didn't have an ROI in the next 7 years. It will be hard for anything to compete with the efficiency of Waymo.

Each Waymo vehicle is probably close to half a million USD in just hardware cost.

I don’t think fixed route transport infrastructure is going to have trouble competing on efficiency.

The hardware costs for Waymo are estimated at $30k.

Source?

They were targeting $7.5k for their in house honeycomb lidars and they have 12 of them - that’s 90k already.

https://www.theverge.com/2021/8/27/22644370/waymo-lidar-stop...

They also aren’t close to the $7.5k target (there isn’t any public source for that so you’ll have to take my word for it).

Also $30k wouldn’t even cover the base vehicle.

This is an estimation for the self-driving hardware cost (computers, LIDAR, sensors). It does not include the base car price, as it can be easily optimized down to almost nothing (sub $10k).

The price is somewhat of a guess, several years ago, the hardware in Waymo was priced at $130k by Munro&Associates. But since then the cost of the LIDAR sensors fell by 90% or so, reducing the main expense.

And Baidu has cars on the road that cost $30k for the _entire_ car. So presumably, so even a couple of pricier sensors won't affect the estimate too much.

> include the base car price, as it can be easily optimized down to almost nothing (sub $10k).

Waymo uses brand-new electric Jaguars.

Sure. Because why not? The cars are in the experimental stage, so they might as well use nice ones.

But there is no _reason_ to use Jaguars and not specially-built smaller and less powerful cars, when Waymo finally starts a real rollout.

Source? None of those numbers make sense.

> The price is somewhat of a guess, several years ago, the hardware in Waymo was priced at $130k by Munro&Associates

10 years ago they had even more sensors dotting the car, instead of one honeycomb on each corner they had 2, so I find $130k hard to believe given what we know about the sensor kit today.

> But since then the cost of the LIDAR sensors fell by 90% or so, reducing the main expense.

I do not know of any lidar that has done that, and Waymo makes their own and we know their price(-ish) (and quantity). I think they’ve actually gone up in price (but also capability - honeycomb 1 vs gen 2).

Are you talking about raw material costs? Or is that one of these extrapolations of if we scale everything to millions of cars and realise no inefficiencies and nobody making any money in the supply chain?

I'm talking about the current cost of the self-driving system, that is already produced by companies that charge a significant markup. With volume, it will go down more.

I'm not including the base vehicle in the cost. It's highly variable, and can be as low as $10k for small personal intra-city taxis.

China has already launched a $30k taxi: https://www.forbes.com/sites/bradtempleton/2024/05/14/baidu-...

This _completely_ blows any transit out of the competition. Literally nothing can come even close in the end-to-end efficiency.

Why does it blow away any other public transit? That can't be true because if you put the same self driving tech into a bus, you already am an order of magnitude cheaper per passenger (likely more). Moreover let's assume robotaxis are cornering the market and make all other forms of transport non viable. Why would the public then maintain the roads? So at that point at least costs are suddenly going to explode.

Sigh. People are WAAAY too accepting of urbanist propaganda.

Buses are _barely_ more effective than cars. A regular passenger car with 4 people is more efficient than a city bus. An EV needs 2.5 people (these numbers are for the US).

The explanation is simple:

1. Buses have to drive _all_ _the_ _time_, even when there are few passengers. As a result, the average bus load tends to be around 10-20 people. And you can not increase the bus interval to compensate for it because it makes off-rush-hour bus commutes impractical.

2. Buses have INCREDIBLY polluting components: 2-3 drivers for each bus needed to provide the service. They are by far the dirtiest part of the bus. This part can be removed with the self-driving hardware, but...

A full self-driving bus also makes no sense. It defeats the main advantage of self-driving: door-to-door transportation.

That being said, self-driving mini-buses seating 6-10 people are a good idea for rush hour transit.

> Sigh. People are WAAAY too accepting of urbanist propaganda. >

Sigh people just like to make statements without evidence to back them up.

> Buses are _barely_ more effective than cars. A regular passenger car with 4 people is more efficient than a city bus. An EV needs 2.5 people (these numbers are for the US). >

Evidence? Moreover you know that average occupancy rates of cars are around 1.5 [1], for short trips like commuting it's more like 1.1 [1] so that's a factor 2 off from your 2.5. So even if we believe your numbers you have to explain how you're going to increase occupancy rate by a factor of 1.5 to 2 before they become just better (not even blowing out of the water). [1] https://www.eea.europa.eu/publications/ENVISSUENo12/page029....

Note I could not find numbers on buses, but trains in the above source have occupancy rates of 50%.

> The explanation is simple: > > 1. Buses have to drive _all_ _the_ _time_, even when there are few passengers. As a result, the average bus load tends to be around 10-20 people. And you can not increase the bus interval to compensate for it because it makes off-rush-hour bus commutes impractical. >

And robotaxis have to drive empty to and from the person they are picking up.

> 2. Buses have INCREDIBLY polluting components: 2-3 drivers for each bus needed to provide the service. They are by far the dirtiest part of the bus. This part can be removed with the self-driving hardware, but... >

Not sure how we should account for bus drivers, considering that even if they are not working as bus driver the person is still around (also should we include the emissions from all the engineers working on self driving tech at the moment then) . However your statement is also false in most western countries, at least green house gas emissions of private households are dominated by transport (i.e. Cars).

> A full self-driving bus also makes no sense. It defeats the main advantage of self-driving: door-to-door transportation. >

You're contradicting yourself. If the bus driver is the most polluting part of the bus (according to your statement above), then it would definitely make sense to get rid of them.

It would be great if your statement was true and robotaxis are the most efficient thing ever. I'd love to see well laid out evidence for this, but from what I just found your statement is not supported by reality.

> Sigh. People are WAAAY too accepting of urbanist propaganda. > > Buses are _barely_ more effective than cars. A regular passenger car with 4 people is more efficient than a city bus. An EV needs 2.5 people (these numbers are for the US). > > The explanation is simple: > > 1. Buses have to drive _all_ _the_ _time_, even when there are few passengers. As a result, the average bus load tends to be around 10-20 people. And you can not increase the bus interval to compensate for it because it makes off-rush-hour bus commutes impractical. > > 2. Buses have INCREDIBLY polluting components: 2-3 drivers for each bus needed to provide the service. They are by far the dirtiest part of the bus. This part can be removed with the self-driving hardware, but... > > A full self-driving bus also makes no sense. It defeats the main advantage of self-driving: door-to-door transportation.

Even if you focus only on emissions this completely ignores the cost of congestion, which is huge.

Your complaint about self driving buses makes no sense either. If the most polluting part of the bus is the driver then removing the driver makes the bus far, far less polluting.

When your arguments don't even make sense on their own terms it suggests that you're making them from an emotional position instead of a rational one. That's ok: if you don't like buses just say so, but be honest about it instead of making spurious arguments.

> Even if you focus only on emissions this completely ignores the cost of congestion, which is huge.

Congestion should be fixed by removing buses, de-densifying city cores, and forcing companies to build offices in a distributed fashion.

Meanwhile, replacing buses with shared taxi-style vehicles will do most of the job, while _reducing_ congestion. It's a bit complicated, but it's entirely possible.

The reason is simple, there is an unavoidable tension between the density of bus stops and the average speed. As a result of frequent stops, in most cities buses move at an average speed of less than 20 km/h.

For example, in Seattle it's 15 km/h. This is just 3 times faster than a rapid walk!

If we reduce the number of cars by 2x by adding mild car-pooling during the rush hour, then we'll have more than enough throughput to eliminate congestion _and_ buses in Seattle. This does not generalize to all cities in the US (e.g. Manhattan needs a serious demolishing to become sane) but usually, it's in the same ballpark.

> Your complaint about self driving buses makes no sense either. If the most polluting part of the bus is the driver then removing the driver makes the bus far, far less polluting.

Sure. But why stop there? Buses have an INCREDIBLE impact in the number of lifetimes wasted during commutes.

> When your arguments don't even make sense on their own terms it suggests that you're making them from an emotional position instead of a rational one. That's ok: if you don't like buses just say so, but be honest about it instead of making spurious arguments.

Nope. There are no rational arguments _for_ urbanism. It's a failed obsolete ideology, and it's leading to the downfall of democracty and the rise of populism.

Bus stops are often set too close by municipalities, but that’s driven by the lack of density in US housing. Density drives efficiency.

> Manhattan needs a serious demolishing to become sane

Ah yes, lets demolish one of the most economically productive regions of the USA, both in GDP / capita and GDP / km^2 in order to make it easier for people to drive through it.

Listen to yourself, this is deranged.

> Bus stops are often set too close by municipalities, but that’s driven by the lack of density in US housing. Density drives efficiency.

Doesn't matter, dense cities start having their own issues. Instead of taking "the bus", you'll need to wait for the correct bus to arrive. Also, density drives up misery and nothing else. Proven by the birth rate.

> Ah yes, lets demolish one of the most economically productive regions of the USA, both in GDP / capita and GDP / km^2 in order to make it easier for people to drive through it.

Yup, exactly. There's no freaking reason so much GDP has to be crammed into several square miles of space, sucking the life from everywhere else.

> Congestion should be fixed by removing buses, de-densifying city cores, and forcing companies to build offices in a distributed fashion.

Yes, let's solve congestion by forcing urban sprawl. Forget any efficiency gains by using denser infrastructure, just make everyone drive 10x as far so there's 10x as much road and therefore 1/10th the congestion!

We already do this. You just described the city of Houston. I've been there, it's ass. And the 14 lane Katy highway does it no favors.

> A regular passenger car with 4 people

How common are those? I always see them with just one person on board.

Others have largely dealt with your arguments, but to this:

> > And you can not increase the bus interval to compensate for it because it makes off-rush-hour bus commutes impractical.

Most transit systems DO operate different intervals during rush hour. Most places I've lived there's been anywhere from 3-5 different intervals at different times of day: At a minimum a night schedule which might be once an hour or not at all, a rush hour schedule, and 1+ day-time non rush-hour schedule.

I do agree that mini-buses would be an advantage though, once you don't need drivers, and that'd further reduce the advantage of small self-driving cars by allowing for far more routes.

It is really efficient, at sitting in traffic with all the other cars 8-/

And yet, still faster. That's the paradox of cars.

Cars are very much not faster than trams in high traffic conditions. Nevermind heavy rail.

Yes, they are. Do an experiment, drop ten points randomly on a city map. Then plot routes between them, using Google for transit and cars.

For most cities, cars will be about 2-3x faster. For three simple reasons: no walking, no waiting, no stopping.

And that's the paradox. Cars are better than transit, yet modern cities are hell-bent on destroying the car infrastructure.

You can also check this site with isochrones for different transport modes: https://www.geoapify.com/isoline-api/

> Cars are better than transit

And are even better when parking isn't a concern (e.g. taxi service)

Public transit isn’t supposed to have a financial “ROI.” Are highways expected to turn a profit from tolls?

The libertarian answer is yes highways should. Most self proclaimed libertarians refuse to go that far - if you allow for highways to not make money then transit shouldn't be held to the higher bar.

I always find this a dumb idea. Transportation networks enable things to happen that comes back as taxes, that is. Same for education, or other public services.

Fair, but how unprofitable should they be? -$5/passenger-mike? -$12/passenger-mile? I think we can do a lot better than the current US mass transit status quo.

In 2022, the NYC Subway budgeted about $0.75 per passenger-mile (and that was during Covid, when ridership was very low) [1]. You’re really overestimating how much public transit costs to run. Private vehicles are an extremely inefficient way to move people around, hence the cost of Uber/Lyft/taxis.

[1]: https://data.transportation.gov/Public-Transit/2022-2023-NTD...

NYC is special in that it's on of the few places that subways make sense in America. That said, operating costs are common but extremely misleading way to measure transit costs when new tunnel costs $2.2B/mile.

That's a useful data set. Thanks for sharing.

NYC is special in that it's one of the few places that subways make sense in America. That said, operating costs are common but extremely misleading way to measure transit costs when new tunnel costs $2.2B/mile.

The proper way to recoup the capital cost is through the increase to land values that arise from building the railway. You buy land around the future stations and put a shopping mall or business center on top.

That and/or land value tax, yes.

> NYC is special in that it's one of the few places that subways make sense in America.

The built environment is not fixed or exogenous. NYC is great for the subway because it was built around the Subway. If America followed international best practices, it could go a long ways towards steering other places' built environments too.

Single passenger cars still have a problem with density even if there's no need for a driver. Combining multiple people into one trip can help, but also lessons the utility of Waymo if riders have to go out of their way to pick up additional passengers.

Getting 1000 people downtown could be up to 2,000 Waymo trips (one trip to drop off the worker, another trip for the car to go back out to pick up another passenger). While one of these 56 passenger very light rail cars can do it in 18 trips. A light rail vehicle like the Siemens trains used in San Francisco can carry up to 200 people at crush loads, so that's 5 trips.

Yes, I always say: Next time you see mass transit pass, imagine all those people in their own private cars on the road.

You mean it's very difficult to compete with a company that is massively subsidised by public infrastructure? That's what really killed freight rail in most of Europe, make the train companies pay for track maintance (often the rail companies even want this because it keeps competition out as well), while trucks atpapy very little of the cost they impose on the public (i.e. much higher road usage, causing most of the traffic issues).

If this were true, cities would have abandoned mass transit for taxi system decades ago. The requirement for there to be a warm body driving a taxi isn't among the prime causes of its inefficiency.

The big AV transit efficiency gains* can only happen when nearly all human drivers are removed from the road. Alas, that's at least 20 years ahead of now**, or more (e.g. if tech stalls for some reason, though I consider it unlikely). Otherwise they'd be limited by having to account for human drivers and that limits speed and throughput enough so other solutions are a must.

* Think having much higher speed limits (as far as humans are concerned, nonexistent), or mass coordinating movement over the entire traffic.

** We can reasonably estimate the minimum without bothering to ask how fast the tech will improve: Even if the tech were available now, think about fleet replacement costs which no one group would be too eager to pay. Best case, it's the typical 'make a concentrated pressure group lose for societal benefit' and we know how that politics goes. It will happen, but slowly.

*** Another thing to account for is that there's no good reason to design an AV car like a normal car, and there'll be some iteration time over that too.

Higher speeds increases noise and stopping distance, even for autonomous vehicles.

True, but this can be compensated for. Current vehicle design is based on human-operated gas vehicles - so it better be aerodynamic (to save gas), and a human needs to be in the front (to see) with only a glass to separate, and it needs a particular stopping action (again a consequence of carrying humans without enough separation). This has unfortunate implications for noise and stopping distance. Electric-powered AV can have creative designs to enable much quicker (yet safe) stopping action, an action which AV would also make rarer.

Autonomous vehicles can have faster reaction time, but once they hit the brakes, stopping distance will still increase with speed because it's limited by the friction between tires and pavement. Unless you put parachutes or rockets on these vehicles, or thrust spikes into the pavement...

There's no reason a car should have only 4 wheels, we can even have special wheels deployed only when the breaks are hit at high speed. The AI will be disciplined enough to always use them when necessary (or maybe use an automatic system based on speed alone?).

Or you can have a different wheel count and arrangement normally, as the AI can be trained for this. We don't have to standardize AV cars as much as we have to standardize cars for humans.

Stopping distance is actually unaffected by the number of wheels a vehicle has.

Isn't friction a function of surface area? You can increase surface area that way, and the extra wheels can be made to have more friction than usual if the design is such they are not used normally.

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