Should traffic lights be abolished? (2021)
freakonomics.com
freakonomics.com
But there is a learning curve. Every new roundabout causes a significant jump in crashes for a short time. Though, those crashes tend to be "glancing blows" that cause less serious injuries due to the angle of attack imposes by the roundabout.
Smaller cities and towns in Indiana are adopting more roundabouts near congested areas. It's important to introduce them gradually and give drivers time to acclimate.
https://www.nytimes.com/2021/11/20/climate/roundabouts-clima...
Now Carmel is replacing some stoplights with roundabouts. This man's opinion is that they are not always better. But so far, they've never been worse.
Afaik, the general trend is to put a stoplight going into the roundabout for the few directions that cause a problem so that the "side streets" get a chance to go.
It just makes the thoroughfares slower for no clear reason.
There HAS to be a lump big enough to cause someone to go the right way around.
So ideally the roundabout also doesn't encourage sweet jumps. (Unless there's a very well-designed designated landing spot that prevents damage to the vehicle. Probably tax dollars can be spent on better things.)
I assume those are affordances so buses (say, school buses), trucks towing trailers, and stuff like that, can actually use the roundabouts. They'd be damn tricky for them to navigate, otherwise.
I have a reason to visit Indiana now! Cool. I wonder how I can sell the family on a trip to Carmel or similar city :).
The town I grew up started adopting roundabouts as I started driving. They're awesome and so much faster than red lights! They annoy my older relatives and coworkers as well.
Adding some sort of pseudo-rotary has made Worcester, Massachusetts's Kelley Square go from Massachusetts's most dangerous intersection down to its eighth most dangerous intersection lol
Somehow still never had any traffic lights at any point.
Before: https://www.wbjournal.com/sites/default/files/2019-10/kelley...
After: https://www.gannett-cdn.com/presto/2020/12/31/NTEG/86da81b0-...
[the triple pedestrian conflict at each entry threw me at first - but if you consider where the driver is likely looking, it makes sense]
Roundabouts, offset T-intersections and grade separation all make traffic safer by removing conflict points - it's not the removal of traffic lights that improves the safety. Four way intersections put traffic directly on collision paths at high speed, meaning if anyone makes an error (missing the light or otherwise), you have an awful crash.
It's relatively rare in the UK to have four way stops or high speed four way signal controlled intersections. One of the weird things about driving in the US for me was the prevalence of both of those things.
Coincidentally, where I live is known for its many many roundabouts and not only are they safer but they also offer superior cross-way throughput when traffic is heavy. And they allow the "middle" of the intersection to store a chunk of traffic who are protected from full speed impacts while still letting vehicles flow slowly through the perpendicular axis.
US could stand to gain massively by replacing about 90% of their intersections with roundabouts - but the remaining 10% could probably stay lights and everyone would win.
Still get the safety advantages of a roundabout but they can carry uneven traffic.
Alternatively, offset junctions are also common.
But, if that's not possible, the bike is either acting like another car (in the roundabout) or a pedestrian (crossing several entry/exit points). Less than ideal, but still better than getting t-boned at >30kph as happens at 4-way stops in the US.
Here's an example, but it relies on drivers yeilding to cyclists (they're supposed to but usually don't in the US, regardless of intersection and signage). https://www.youtube.com/watch?v=wEXD0guLQY0
1) Cars need to slow down to go through the roundabout safely, 2) If there is an accident it is more of a side-swipe type accident than a t-bone or head-on accident.
But as others have said they aren't the best solution for all situations but they could be used a magnitude more than they currently are here in the U.S.
[1] https://www.oregon.gov/odot/Engineering/Roundabouts/Roundabo...
Imagine this. Driving on the right. Roundabout with four exits. North, East, South, West. Heavy streams of traffic entering from north and west. Most traffic exits at east therefore nothing to slow north enterers. West enterers hopefully get the breaks in north entering traffic. Trying to enter from south is really difficult because north and west enterers keep it full.
Im from a chunk of Australia known for a tonne of roundabouts and observed the same issue. My theory is that this is actually roundabouts working as intended, despite the frustration of the South-Enterers.
Basically, if the flow of traffic is both moving too fast and with too great a vehicle density to allow for safe entry (even if slow, like 1 SouthBound Vehicle for 5x Northbound + 5x Westbound) then the traffic organism is actually distributing resources based on need, rather than convenience. The flow WILL automatically correct itself as the population of vehicles diminishes, the question is if the WAIT time for Southbounders (and the population of Southbounders) is sufficiently large that interfering with their flow is actually delaying more people than the North and West routes, but that is more of an issue of roundabout placement than it is the roundabout itself being inefficient.
(^^The above is all 100% observation and guesswork, anyone with some education on the matter want to chime in?)
Traffic lights invite aggressive driving because drivers want to make it through the green (or orange) light. Basically, drivers end up accelerating into the intersection, rather than slowing down and be more careful. It's the _exact_ opposite of what should happen.
Traffic lights are the result of a misplaced obsession with efficiency and high technology. The idea we can perfectly manage complex systems (very mid 20th century mindset). We need a value shift. Safety is more important than speed.
I've also seen two lane roundabouts which aren't bad, but now there are roundabouts where you go from two to one, or two to three lanes driving inside the roundabout! Definitely safer than stop signs but the most un-intuitive intersection for new drivers.
Traffic is easily modeled as buffers and context switching. As traffic flows through an intersection, the buffer for that direction drains. When it switches, there is a penalty to context switch (the traffic must come to a stop, some traffic must finish through the intersection). The perpendicular buffer (which has been filling), requires the intersection to clear completely before proceeding. Then its buffer can empty.
4-way stop signs introduce context switching for every car (the intersection must clear before proceeding) and you must stop every intersection, buffer stalls.
Round-abouts ensure more rapid context switching (only wait for the car to your left to clear), no waiting for an empty buffer to continue to be empty, and fewer buffers per intersection (think left turn buffer, right turn buffer).
That's exactly what I said. Traffic lights for governing car traffic are the result of a modernist obsession with efficiency; in this case a pre-occupation with car travel speeds, throughput, ... as if these are the only things that matter. I gather you view that as a positive, but I see it as a very impoverished monomaniacal mindset. That technocratic value system has poisoned (literally and figuratively) the public realm. We need less of it.
Yes, but:
Around here, typical light cycles are 2-3 minutes, and intersections often sit idle for 60+ seconds. When there are power outages, and the lights switch to four way stop mode (blinking red), traffic usually improves. Also, the California state government has basically mandated programs that intentionally increase congestion.
They call it traffic quiescing, or say they want to reduce commute miles driven per year. No, they aren't providing meaningful improvements to public transit or bike safety.
No. Phased out over time in some places maybe, not abolished. Implemented in some new developments, absolutely.
While roundabouts can work more efficiently they require the roads and traffic usage patterns to accommodate them. Additionally existing intersections designed for lights and putting in roundabouts would require cities in many cases to use eminent domain to acquire the land around them or to buy out land/properties from people. The excessive use of eminent domain would lead to endless legal battles that would deplete city budgets.
Some existing large intersections could be retrofitted for a roundabout and some small cities are in fact doing this. I've also witnessed this occurring in rural areas that have intersecting highways where the state already owns the land around the highways. This reduces brake dust, engine brake noise and keeps freight moving.
At the same time, I took "abolish traffic lights" as a North Star for future design as well as making changes to existing infrastructure where economically and physically feasible (i.e. stay practical). Not rip out all traffic lights everywhere and replace them with roundabouts or rotaries, as the case might be.
https://www.google.com/maps/@40.7957351,-74.3405952,17z
It's a circle, with traffic light, but also still an intersection. Fun!
If you imagine traffic on a motorway going North/South and an A-road running East-West, at busy times, the traffic going from East to West and West to East will be significant enough that traffic coming off the motorway is not able to find enough space to enter the roundabout (or, not enough to meet the demand). Without traffic lights, traffic will soon back up down the slip road onto the motorway, or worse, will try to force its way onto the roundabout instead of giving way to the right.
Traffic lights make this much safer.
In general the UK has very few flyovers. I sometimes suspect the SF Bay Area has more flyovers than the entire of the UK.
Traffic lights are also used to give priority to pedestrians and cyclists on junctions where it would be unsafe to rely on zebra crossings or pedestrian priority - think sharp and low visibility corners.
As far as roundabouts go, the UK has been replacing big multi-lane roundabouts in areas with lots of pedestrians and cyclists with two-way-traffic horse shoes (e.g. Old Street and E&C, plus others outside of London). This allows the centre of the roundabout to be used as public space, and has been found to be safer for vulnerable road users.
I'm all for light-free junctions where possible, and light-free roundabouts work REALLY well in low/medium traffic. But you can't just abolish traffic lights - unless we also abolish cars at the same time.
So taking the 3rd exit on a bike either means following the road all the way around, or just going directly from the entrance to the 3rd exit, as cycle lane is usually preserved where the road used to be.
The safest route for bikes is to take the segregated bike route at the bottom of the horseshoe, then using the mixed bike and pedestrian crossing to go directly over the mixed used paved area, then use the mixed crossing on the other side to join the A201. Either that, or use the segregated cycle path, then horseshoe near London Rd.
But honestly, on a bike you would just avoid the horseshoe completely. There’s usually better cycle routes that are more direct, and avoid large junctions like the E&C horseshoe.
The essence of of is segregated cycle lanes with cycle-only traffic lights. Nothing magic.
Neither of them are fully separated (yet at least - they're still being worked on), but they're a lot better than what came before.
Trafalgar Square also used to be a roundabout back in the day, though it got converted to a peninsula before bicycles were fashionable so that's not a great example.
Highbury Corner is another example you can look at.
Roundabouts work best when the traffic is below a certain critical level; above that and you're still stuck for ages except with no automated system trying to bring "fairness". In some cases this can be solved by .. adding traffic lights to the roundabout.
There are plenty of small intersections with traffic lights that aren't any wider than two opposite lanes with no median and no shoulder, only big enough for two vehicles to pass in opposite directions. They would need to be expanded to put a circle of any size in the middle, especially if a big truck was expected to make it through safely.
They don't take up any extra space, but they do probably require drivers to intuitively understand the concept and priorities before they can be introduced.
Here's a satellite view of a random one near me: https://goo.gl/maps/NJ2KpYdMP1reQA1u5
Its an upgrade of the American 4-way-stop with better defined priorities for entry.
Additionally, there is frequently extra space in the existing intersection. From parking lanes, shoulders, etc.
https://www.google.com/maps/@56.5902318,-3.3376212,3a,75y,34...
Worth noting this particular roundabout is in a small farming town on the edge of the highlands. Already slow speed road and low volume. But, shows that many 4-way stops within the US suburbs could easily be swapped with a roundabout during normal road repaving without much additional cost (yield signs to replace stops, some paint).
That intersection you showed is clearly big enough. This one doesn't look big enough. Or is it? There are smaller intersections than this one, also. (And I realized that this one might be a bad example because it's not four directions.)
The issue I've seen with them in the US is many US drivers ignore pretty much everything about the painted circle which creates a really dangerous situation. They treat those intersections like 4 way stops (including driving over the circle) and that's a major problem.
When traffic is light, traffic lights make you wait a long time for no reason. When traffic is heavy they add insult to injury by taking 2 or 3 cycles to clear out the stack of traffic you're waiting in -- and that's just the immediate intersection, frequently traffic stacks up to the point that traffic flow is impaired in preceding intersections. That's how traffic lights turn a 5 minute drive into a 50 minute drive.
Works decently well.
I've also seen fancy sensor-equipped traffic lights where the traffic flow was improved by a power outage turning the intersection into a (legal default) 4-way stop. Major intersections. During rush hour.
That fits one of the main points made in this article: traffic lights slow down traffic. Another one is that decreasing speed on intersections increases safety.
The magic of roundabouts is that they accomplish the latter without needing the former.
The general traffic is probably 95% favored to the direction I am going, and I really wish they would just leave it green until the other direction actually needs it.
Maybe they have it this way on purpose to indirectly prevent speeding? I wonder if that's a consideration for traffic light logic or not
We are definitely stuck with idiots for local traffic planning. And those clever sensors - there is a huge difference between (A) a traffic light checking that Feature Box in PowerPoint (or Flash, or Microsoft Bob, or whatever software the local traffic planners use), and (B) traffic sensor technology being usefully implemented at the light's real-world location.
The only part of my route that I always have to stop, is the traffic light. Roundabouts are awesome. Our complete infrastructure is pretty awesome to be honest. Other countries could learn.
The thing that's happening right now is that many large cities have more or less enabled the possibility of carless transport. Cycling is now completely viable and even better, costco has a foldable ebike for like $400. Weather sucks? Work from home instead. Gotta go? Taxis and buses exist. What do you pay in car insurance? $1000/year? How many trips in the bus is that? Many! You also dont pay for parking anymore. Cycling is great exercise burning fat instead of money. It's a huge net benefit to society which is 70% overweight. National wealth will certainly increase.
Which brings me to traffic lights. Cyclists already don't obey them. Why don't we just abolish them? Traffic lights function just fine when they go out or blink red.
If stop signs replacing all traffic lights is an inconvenience for cars... might I recommend a bike?
>The thing that's happening right now is that many large cities have more or less enabled the possibility of carless transport.
I actually like to leave the cities I live in sometimes. Or maybe I don't live in a city, and I want to visit it with my car.
City residents can do whatever they want but I for one will simply not come in in general if it’s too big a hassle. And that’s fine. I have plenty of other things to do.
Agreed, it is fine. As a city resident I would rather have fewer people coming in and a more walkable environment than more people coming in and streets clogged with cars. We should make sure the transit is excellent, but if some people don’t want to come in because they want to drive and it’s difficult, that’s fine! Too many people driving in makes the city an unpleasant place to be in.
It's fine to own a car, park it in your garage space in a city, and use it to drive out of the city from time to time. It isn't OK for cars to dominate 50% of the space in modern American cities for roads, free street parking, and parking lots. Particularly because it comes at the expense of space that could be used for more scalable transportation solutions.
> Or maybe I don't live in a city, and I want to visit it with my car.
Sure, feel free to drive to the other city by car. But in a more scalable world without hellish traffic, you'll have to get around on foot, by bike/scooter, or using public transit in the city. Because cars aren't scalable.
50% sounds extremely generous. There are 8 parking spots per car and one car per person which is around 350m^2 of area per person (some portion of which is stacked).
This is one median lot per household on parking alone.
To be upfront, I'm a car guy. My last car had >700hp, currently a hot hatch. Soon I have to go dadmobile, vw camper id buzz... oh do tell me more.
My bike? I bought one of those huge/wide bike seats. My bike seat is worth more than my bike lol. I find it crazy there are people with ultra light carbon fiber sport bicycles about to be stolen any moment. Nobody stealing my piece of shit bike.
>You can't just tell someone to completely change their lifestyle to avoid potential problems, and then act like they are the insane ones for not wanting to listen.
Because of the boon on cycling. We suddenly have big lobbying and activism toward promoting cycling.
The thing is, don't just write off this factor. There's lots of good benefits to society if we all move to bikes and shared infrastructure to rental vehicles or transportation services.
>I want a car. I like my car. Demanding that people give up their ability to get in a car and drive somewhere so that all of America's infrastructure can be changed is insanity.
I don't think anyone is going to that extent to say you can't drive anymore.
>I actually like to leave the cities I live in sometimes. Or maybe I don't live in a city, and I want to visit it with my car.
Nobody is saying you cant drive. No politician will survive assassination if they banned cars.
There are ebikes with >100km electric range that can go 35km/h. Going to be hard to tell me that setup won't do what you want it to do.
The Netherlands does this properly. But as a European having traveled to the USA it is mind boggling how car centric cities are. With all the inefficient and extremely costing infrastructure investments car centric cities require.
A solution for people like you would be to park your car near the city borders and take public transport. But I don't know a single car owner who isn't too lazy to just drive straight into the city.
Having designed our cities around the car will be really frowned upon in the future. It's crazy how much people who use alternative modes of transportation sacrifice (in tax and health) to support this.
So, now you know a car driver who drives about 16k miles a year, and also is not lazy enough to park at city borders & use public transport. & Bart Parking is almost always 60+% full.
> I actually like to leave the cities I live in sometimes.
You can own a car and still use a bike when staying within the city. That's what most people do here.
> Or maybe I don't live in a city, and I want to visit it with my car.
That usually leads to a worse experience than taking public transit or a shared bike, and I don't think this use case should be supported.
The bike vision of the future features all of these tanned, lean people cycling everywhere (and even making turn signals with their hands, which happens so infrequently IRL that I generally note it at once a year), and I guess everyone else just hopes they don't get stabbed if they ride our quasi-subway.
When teaching my kids to drive, they found roundabouts one of the trickier intersections to navigate. You have to read the traffic flow. This person about to enter on your right is going straight ahead, so will block you entering the roundabout[1], but they have to wait for that person coming the other way from you and going straight through, so you can slip in the gap that creates without cutting anyone else off. As with many things it is familiarity and practice that makes them work[2]. I think roundabouts work very well here for the most part. It’s not rocket science[3].
The science of roads and traffic I imagine is a surprisingly nuanced expertise involving a lot of physics and psychology. I find when I cross over the border to New South Wales I feel like a long-tailed cat in a room full of rocking chairs. I eventually figured out it was because the signage was a different distance before the intersection compared to my home state. Once I was aware I could adapt.
[1] We drive on the left side of the road because Australia is in the southern hemisphere.
[2] I bet the first traffic lights caused an uproar. “Why the hell should I stop just because there’s a red light?!”
[3] Oh wait, actually, it is rocket science.
If you live where there is a light that causes disruption or accidents because it needs sensors based on the traffic flows nearby, you should bring it to the attention of your local government. At the very least you could get them to do a study on it.
Yet the people will complain and get their new light, and we'll impose largely arbitrary restrictions on new drivers while letting the chronic crash causers slide and the people who would objectively fail better testing drive.
In the US, the penalties for crashing your car at this point is often being forced to buy a new car since even low speed accidents can total your vehicle, then you also have your insurance rates skyrocket, and you're often on the hook for a lawyer and showing up to court where you can face being responsible for hundreds of thousands in medical expenses. It's a pretty damn punishing system for people who cause accidents. I suspect that most people (alcoholics aside) are not going around getting into one car crash after another after another. It's just vast numbers of assholes each of which thinks it won't happen to them until it does.
It can be as punishing as you say, but rarely is. People buy cheap used cars so it's not expensive as you might think. Basic liability insurance isn't crazy either. You'll rarely go to court unless you are uninsured. And insurance will typically cover medical expenses, and comprehensive will even help you buy a new car.
It would be pretty simple to revoke people's license if they cause more than one accident in 5 years.
A teenager who gets into repeated accidents is probably a good example of someone who'll probably turn out fine once they grow up a little, but something like ADHD could easily continue to be a problem if they don't get it addressed. I'm not sure if there are places where a person can be required to be medicated to drive (like some people are required to have glasses/contacts or supplemental oxygen anytime they are driving) but it wouldn't be a bad idea.
It's like when you approach a traditional 4-way intersection, some of which add a left-turn-only lane and some of which add a right-turn-only lane: once you learn the general philosophy, you will be fine.
Those bug the shit out me to too. Sure, you get used to them quickly enough when you drive on those roads all the time, but everyone who hasn't encountered it has to figure it out and depending on how well marked it is even people familiar with the rules have to deal with confused people who haven't figured it out yet.
I especially hate those left-turn-only lanes which leaves people who could have turned right on red stuck behind people who just want to go straight. The people who want to go straight would have to wait for a green light anyway, so why not leave them stuck behind the left turners who also have to wait and let traffic flow for the people making right hand turns?
It would have been so much better if it was a right only, and straight+left lane.
There is of course an exception to this. If there is a protected left turn cycle, then the left turn lane needs to be its own lane, but that was not the case at the intersection in question.
This is simply not universally true. I've seen roundabouts with different lane routing assignments even within the same neighborhood. It's incredibly hostile to visitors.
Even worse are the roundabouts that are wide enough for multiple lanes, but with no lane markers. Just kind of a circular flood of cars, with people on the inside suddenly realizing they need to get off, etc.
Perhaps in that case you're meant to use overpasses, or maybe the data says that roundabouts work fine, but they don't seem to.
Philly has been notorious for this regarding stop signs.
In any case, Arizona has a LOT of roundabouts. They take considerably more land so it would basically be impossible for the vast majority of existing in-city street corners. Arizona uses them more in rural/not yet developed areas. Definitely help speed up things, but I would say at this point, it will only be useful for new, very spread out cities.
California: "Hold my kombucha."
Massive ones like you describe don’t need stop signs.
https://bikecity.amsterdam.nl/en/inspiration/experiment-traf...
However, you may only have to cross one lane at a time which may be a bit better.
It doesn't lead to as many accidents as you'd think, but boy is it a nerve wracking experience crossing these roads at night.
Like, would roundabouts work on the 4 lane roads that are always packed with traffic here in Los Angeles?
Personally I doubt it would help traffic in any significant manner but who knows.
In most of the Los Angeles area, there's not room to drastically expand intersections to build usable roundabouts, compressed roundabouts are even worse at throughput.
Multilane roundabouts exist, but they're tricky to navigate and would be tough to have high throughput for if most people want to continue traveling in the same direction after the intersection.
Personally, I love roundabouts. They're fun to drive around. But I have seen (and there's lots of reports about) semi tucks crawling over them at 5mph or less because they're all built too small to support a semi with a 50' trailer.
My vote is, once we eliminate the need for Semi trucks for deliveries in the city, sure. Roundabouts everywhere. But until then, let's keep infrastructure sane for all the users of it.
Whether it's on the highway or around neighborhoods with speed bumps and pedxing, you see (and hear) cars speeding away only to endanger the next person at the next stop sign or traffic light, or car in front of them.
(I can "1 pedal drive" my manual down a hill in 2nd or 3rd, go a reasonable speed, automatically be slowing to go over a speed bump)
In a manual transmission this is from engine braking, without gas applied, it immediately starts slowing down.
This makes traffic flow better by reducing the need for last minute stopping, predicting when you need acceleration, reducing speed automatically when the driver is cautious, and generally increased attention and awareness.
(*) actually I couldn't find an official stat for this. The number of registrations is slightly higher but a fair number are "collector" cars that are very rarely driven, or mostly in very rural areas. I'd actually suggest in the cities where the vast majority of us live, among cars that are driven regularly manual transmission is a good deal rarer, certainly less than 20%.