Phantom traffic jams, and why lane expansion isn’t really successful
cnet.com
cnet.com
...if the only benefit of building more lanes was reducing mean transit time at rush hour. You could also just build a one lane road and have the toll so high that only a single driver could afford to use it; that would be optimally “beneficial” in this model.
But that road down the way that is so congested right now? If we expanded it, and it could convey more cars at the same level of congestion- where did they come from?
The latent demand represents potential traffic that either:
1) is doing just fine taking a different route right now
2) isn't particularly economically valuable, i.e. not worth waiting through traffic for
3) things like future sprawl enabled by wider roads today
In order, #1 is not particularly valuable to reroute, it was doing ok. #2 is not very valuable either, though perhaps a little. #3 creates new demand, but the only thing we get in return is lower density.
So I guess in sum the point is that all the most economically valuable travel is already happening, right now, and by widening the road we add only the travel that has such marginal economic value it's not worth doing today. So the more we widen the road, the less & less economic value we get in return.
With schedules and business operating hours, many economic activities are impossible due to hard time constraints.
I don't see how your argument would be less applicable to a city with two dirt roads.
There is a classic coordination problem regarding private/mass transport: as long as mass transit lags behind personal vehicles in convenience (and status), it is in the interests of car users that everybody except themselves switch to transit.
Was adding the lanes a win for the city? The commuters? The environment?
It is counter intuitive, but if you think about it. Everyone has a commuting pain threshold that will cause a change in behavior. If a stretch of highway takes 10 minutes less because of additional lanes, then people will start commuting from 10 minutes further away.
Fortunately it's really easy to exactly quantify trip times, cars per lane, and similar. Quite a few studies have shown short term benefit, but within a year the traffic is within 0.1% of what it started with before adding the lanes.
It was a win for the local economy.
By allowing more people to drive to and from locations they please, you are allowing more people to work jobs they otherwise wouldn't be able to, and purchase goods and services they wouldn't otherwise.
I'm rarely a fan of government spending; but, roads, police, and firefighting are probably some of the least evil.
A street is made for transporting humans first and foremost. It has sidewalks, driveways to houses are accessed directly from the street, and pedestrians can cross with relative ease, to the point that crosswalks are basically unnecessary.
A road is made for transporting cars first and foremost. There shouldn't be many residential driveways directly leading into a road, there may be sidewalks but they're not going to get used often, and you should rarely see pedestrians trying to cross. Crosswalks are very necessary on roads.
There's no getting around the fact that we need roads. Cars and trucks need ways to move long distanced quickly. The problem becomes when city designers try to mix streets and roads (to make a stroad), leading to massive arteries running through the heart of a residential neighborhood. Proper city design puts roads outside of pedestrian-heavy neighborhoods and fills them with easily and safely walkable streets instead.
There's nothing wrong with an 8 lane road, as long as that road isn't supposed to be used as a street as well.
https://www.strongtowns.org/journal/2018/3/1/whats-a-stroad-...
Interestingly autism rates appear to be higher near freeways (like the ones we put in the middle of cities), yet the anti-freeways-in-urban-cores crowd somehow lacks mindshare compared to antivaxxers.
They've got tons of articles that are right up your alley on the dangers of just putting a 25mph speed limit on a road and calling it a "street".
This one is my favorite: Just Another Pedestrian Killed https://www.strongtowns.org/journal/2014/12/3/just-another-p...
1. https://www.kgw.com/article/news/crime/trimet-barber-gets-2-...
2. https://www.oregonlive.com/portland/index.ssf/2017/05/police...
3. http://www.wweek.com/news/2017/06/02/man-pummels-max-train-o...
4. https://www.oregonlive.com/portland/index.ssf/2018/05/crime_...
Note, they are only a challenge if bureaucrats and big business continue to pour money into centralizing resources in giant cities. In a modern Internet connected economy, there is very little reason to colocate so many government services and large corporations.
Move to smaller over-the-road mass transit for off-hours or have fewer busses. You don't need to have full-size busses at 2am when you can use the smaller busses that schools use at times, for example, or simply have a bus that runs once an hour. You can make sure that major employers are serviced by busses either regularly or at times when their shifts start and stop (factories, for example). You can use van-sized taxis for smaller areas and adjust the routes to meet needs in smaller areas or have electric, automatic trams that run at specific times through the day and less so at night. Intercity travel can be more restricted if the demand isn't there.
Amsterdam has folks scan their ticket for the trams on their way out ... so they can see where folks are going to and from, in general, to better meet demand. Something like this can surely be done in different ways.
Even more, you can create safe walking and cycling paths so folks are more likely to be able safely get to public transport. Have bus shelters many places. Perhaps don't expect it to make a profit. Perhaps tax vehicles to help pay for them when they are available to the user - after all, if you own a car when public transport will adequately fit your needs, the car is a luxury. Perhaps utilize more tolls to help pay for them.
I've never had someone harass me on a bus where I am at now. In fact, I didn't have this issue in the states either when I was lucky enough to live in a place with busses. It would seem the solution would be to actually take care of folks that are homeless and mentally ill. It would make sense to call the police if someone is causing an actual disturbance to others. These aren't problems with public transportation, these are problems with society.
Just providing some benefit is not enough to justify the cost; it must provide an enormous benefit.
Well, maybe those 50% achieve some benefit to themselves and society once they arrive at their destination. Keep in mind, if those people happen to be arriving at jobs they had previously, that's not a greater benefit than before.
However, the movement of people down the road itself is a social detriment. Most people don't to spend time in traffic for kicks and the cost of fuel consumption, pollution, wear on highways and wear on cars is significant. I mean, if somehow I could spend only five minutes in my car per day and still get to my destinations, the benefit would clearly be far greater.
Only if you know how the occupants in these additional vehicles were transiting previously. If they were previously carpooling, or if they moved away from a good (but slightly less time efficient) public transport option, then the social benefit would be somewhere between minimal and nil.
You’re leaving out the taxpayers subsidising their commute.
You have, though, made it harder for the economics to work in favour of apartment buildings and public transit, and as a result made life more difficult for people who choose not to, are unable to, or can't afford to drive. Because people in the suburbs will vote in favour of thigns that make their motoring experience more pleasant, they will demand new construction have off-street parking (even of the residents don't drive), making units tens of thousands of dollars more expensive and less pleasant to walk near, and free or dirt cheap parking in city centres. They will force transit stations to have places for cars to sleep, not people (aka park and ride). Meanwhile, those people who don't drive still bear the negative externalities of the extra vmt and their taxes pay to enable it for others.
In addition to the economics, you've made the public realm more hostile to walking and cycling; car-friendly places are human-hostile.
More vehicle-miles traveled corresponds more emphysema, more extreme weather events, more noise, more light pollution, more cancer, and just more dead people in general. It's impossible to say who or when or how (except in the case of crashes) but every substantial road expansion kills some of the people nearby.
In our town, the city has been switching from tight two lanes each way to one lane each way, plus turning lanes and bike lanes, and these new layouts are significantly more pleasant to drive with none of the old left-turn snarls of the past.
A major downside to Adaptive Cruise is when another driver uses your gap to change into your lane, and your car slams on its breaks because suddenly their car is just inches away from yours.
Recklessly aggressive drivers are learning they can take abuse these safety features in the cars of other drivers, making roadways potentially more unsafe.
I love my Mazda ACC and it will be a major criteria point in future car buying decisions.
A recession is even better than construction at improving traffic, however.
My argument is and has been that highway lane miles have never met demand. More lanes bring more cars simply because the other routes we're equally congested/slow before and now there's a slightly better option with the new mega highway.
The other problem is that if you maintain a gap as traffic speeds are slowing, someone will cut in front of you to gain a car length. Then you have to slow down using the brakes.
I drove stick for years, and your parent is right on. And, back in an automatic, I've naturally regressed, I freely admit.
For more info see: https://en.wikipedia.org/wiki/Induced_demand
A better example would be someone pulling their belt so tight they can barely move, and then letting it out.
You can't reduce demand by constraining supply, all you are doing is making people unhappy.
If your policies are very free, you'll find people will figure out how make things more efficient. For example inexpensive delivery will become possible if there was enough space for traffic.
I know this because I've lived in dense cities (no delivery service - it's simply too hard to find parking, and thus too expensive) and wide urban areas (every store offers delivery because it's cheap and easy).
And that's exactly the opposite of what everyone thinks will happen - they want cars off the road, and replaced with delivery, without actually making delivery practical (i.e. inexpensive).
First, how exactly are you going to limit the use and possession of private cars?
Might work because less lane switching means less slow downs to adjust to new cars entering a lane. And people who don't absolutely need to will remain on right lanes while leaving the left lane for those committed to the lane or for those using it momentarily to pass other cars. Heck,you can even change lane pricing dynamically based on traffic and time of day.
Moving to the faster lanes would be dangerous. Cars merging back into the slower lanes to exit would cause permanent jams in the second lane at every turn-off. Nobody would benefit in the end and the road would be horribly unsafe.
Second from right could cost a bit more than free (1cent per mile for example). It would be an incentive to use it for passing but also to avoid right lane congestion for a negligible fee. Third and fourth from right can cost $0.20 and $0.40 per mile which discourages long term use but also allows those in a hurry who can afford the fees to leave the highway faster and allow for cars in right lanes to use less congested left most lanes to pass slow drivers and lane exit/entrance in their lanes.
Think of it from a network traffic CoS and QoS point of view (also,sorry for the late response,hope you see this)
It would exacerbate economic disparities, forcing poorer people—who are already chronically time-poor as well as money-poor—to spend more time in their car for the convenience of rich people. Rich people already have innumerable advantages in our society, we don't need to go around looking for more to give them.
(As a comparatively rich person, I appreciate living in a society surrounded by people that are—in the main—well educated, healthy and not overly stressed, and I happily pay a lot in taxes to help maintain that. Which is why the USA holds zero appeal to me; you couldn't pay me to live there.)
If you pay a toll anyways,this is an opportunity to save money and use the tollway,where as you would normally take the slow and long unpaid route. This would actually make toll roads accessible to the poor. No matter how I look at it,if you add lanes,they should be paid for so that it would be more affordable abd practical and actually incentivize drivers to cause less jams.
Also,traffic jams are not exclusive to the USA. Maybe it should be modeled in a more politically convenient way? How about fuel tax deductions? You get n deductions where you lose more deduction points by using left lanes? That way there is no added cost to the driver,the tax payers as a whole pay for it.
In other words you're saying that they're closely packed. If the distance between cars is reduced by 50% and their speed has reduced 10-15%, the throughput of that section of road has increased substantially.
As you said, it's speed differential and the use of brakes that causes traffic jams. By that reasoning, the left lane should go the same speed as the right. That would also discourage the use of lane changes which is generally what causes people to use their brakes on the freeway...
And remember the square law of braking. Because the safe following distance increases so much when you increase speed, faster speeds on the freeway decrease throughput rather than increase it.
If the far right or middle lanes are traveling faster than the left and also moving smoothly then someone’s doing it wrong.
Got an article to explain this? It seems counter-intuitive.
Following distances should be based on time, not physical distance. It shouldn't matter if cars are going 30 mph or 300 mph. If everyone maintains a 3 second following distance, there should still be a throughput of 20 cars per minute.
http://www.adventures-in-education.com/math/StoppingDistance...
Note that I don't have a ton of supporting evidence for this sort of thing. One imaginary project that I would love to see if I had the time or the patience for deep research is to just gather a data set and make it public of anonymized traffic behavior -- over a large stretch of highway, have periodic cameras that track every car by license plate (if possible) or car shape, aggregate and remove the identifying data, and output a data set that allows you to slice it by time or by moving segment to directly observe these things.
Tying lane count back to fuel economy, average door to door time, and number of vehicles served would be much more productive.
Similarly, the article recommends hov meters on freeway entrance ramps, but doesn’t mention that they create jams sbout a half mile after the entrance. Again, some sort of metric involving “how many people”, “how long”, and “how much gas” would go a long way.
Fun fact about the Bay Area: my car gets about 75% of epa freeway mileage driving from SJ to Santa Cruz (over a mountain), but only 50% from San Jose to Mountain View (in traffic). This is if I try my best to conserve fuel in the traffic case. If I drive aggressively, the gap widens.
So, reducing conjestion could substantially increase the miles per gallon of the existing silicon valley fleet of cars.
Instead, the “environmentally friendly” nimbys keep voting in people that pay for traffic quiescence “upgrades” that further snarl traffic and increase the local carbon footprint.
All it takes to create a phantom traffic jam is someone to change lanes where the cars behind need to slow or brake to accommodate them.