Do higher speeds reduce traffic congestion?

Speed self-regulates in congestion. Raising the limit will have minimal effect.

 

Speed is not the issue.

It is the difference in speeds between the faster and slower vehicles is what causes the congestion in continuous city and suberban traffic. Higher speeds would just add to the problem.

Drive the German Autobahn and the problem becomes very appearant. I have charcoal grilled steaks in the fast lane of the Autobahn due to no accident just congestion. Too many idiots wanting to drive too fast can produce hours long traffic jams.

 

Agree.

Road design and human behavior are much bigger factors.

 

Traffic jams occuer come from a specific traffic density when someone taps the brakes and we geta concertinba effect, merging traffic where evryone slows etc. In theory robotised cars can eliminate a lot of this,

OR peopel could stop being such cautious nellies and just hit the gas or m,aintan speed instead of the brakes like whent hey get to cornerl. But most drivers are clowns who dont really drive, they sort of distractedly guide a car devoid of any knowlkedge of vehicle dymanics. Up speed with such a drivign populace and whent the density goes up we have more accidents..

 

The issue of speed is a pointless discussion.

The general policy of most governments is it let any idiot drive and impose a speed limit as containment. This doesn't work, since a bad driver is dangerous at all speeds. There is no recurrency or medical checks either, like we have with flying.

Unfortunately, nothing is going to change until cars can actually drive themselves. Then we can take everyone's license away, except from those who are willing to invest the time and effort to be alert, responsible drivers. Those drivers will not need a speed limit.

 

No.

 

Speed limit sign of the future::

Minimum speed 39 MPH: ticket $200
Maximum speed 41 MPH: ticket $150

 

I've thought for years that all limited-access highways should have four lanes per side out of city limits and six per side in cities. If you have commercial trucks limited to the right two lanes - and it would have to be vigorously enforced - and 2+ occupants and motorcycles only in the leftmost lane, you would end up with many less speed-disparity accidents, which is one of the largest accident factors. Plus, you'd keep us motorcyclists mostly away from heavy trucks (Except or entering and exiting, of course).

Speed self-regulates in traffic, so speed limits outside of cities should be eliminated. Montana did this for a while in the late 90's and the world didn't end. Highway speed limits are only for revenue generation anyway.

Cheers,

George

 

So true.

 

I know actual data is discouraged in these things, and I am amongst the crowd that advocates for an 80mph speed limit in uncongested areas on limited access roads, however... There are two considerations that are relevant.

The first is the frequency of collisions that occur; not at certain higher speed limits, but when the traffic speed amongst cars varies more or less severely. The Solomon/Cirillo chart shows a standard array of collisions per 100K miles as average speed deviates. This is a classis "u-chart" with pretty drmatic increases in crashes as the variance gets above 20 mph. If the speed limit was 80mph, the chances of slower-moving traffic being in your midst (trucks, vacationers, motor homes, etc.) is much higher, and so are the chances you'd get into a pretty good collision with them.

The second issue is the one the State of California used years ago during gas shortages to support lowering the speed limit to 55mph. It shows fuel mileage consumption at differing speeds. The problem in California is that everyone generally adds 15mph to any posted limit anyway, so the attempt to save gas failed miserably.

Both issues are still relevant, however, whether you don't want to hit other cars, or if you want to save some $$ at the pump.
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For those of you who are familiar with driving and traffic data, you will know that men, on average, drive more than women across all ages, and it’s not even close. Men age 55+ drive more than more than twice as many miles on average as women of the same age. On face value, it seems like men are disproportionately responsible for all the traffic congestion on the road. Tom Vanderbilt challenges this idea in Traffic, looking at why and when women drive rather than looking at how much they drive.

Both men and women drive a lot more than they did in the 1950s, leading to traffic and congestion. There are many reasons for this. Two that are often named are suburban sprawl (people living farther from where they work) and women joining the workforce. This naturally led to an increase in driving by both men and women. Let’s look a bit deeper.

Other things have changed–or not–since the 1950s. One thing that has not changed is that the women who have entered the workforce still do the lion’s share of errands, particularly those involving kids (think: “soccer moms&#8221. In the 1950s, 40% of car trips were work trips. As of ~2010, a mere 16% of car trips were work trips. The difference is not that people aren’t working or taking public transportation to work (they are actually driving to work more!). The difference is that we’ve added many other driving trips to our schedules. And women do more of these extra errands and trips than men do.

Women do a lot of “trip chaining,” stopping at the grocery store on the way to or from work, taking Johnny to soccer practice, etc. The reason why women make such an impact on congestion is because (1) they are taking these trips during peak traffic times due to inflexible schedules, (2) they they use smaller roads less equipped for large traffic loads (these trips do not usually use the interstates), and (3) the distance between trips is significant (suburban sprawl!). Side note: We women are fairly efficient here in that we can minimize travel times by “chaining” – adding a TSP-like “tour” of errands rather than making individual trips that would take longer.

I blogged about the issue of women having inflexible driving routes earlier, where I argue that dropping kids off at day care often makes taking public transportation impossible. Vanderbilt observes this, too. He also does not blame women for the extra traffic, as our travel patterns are what you would expect when considering the demands of both our families and careers. But there are implications.

In all seriousness, this post discussed traffic from the perspective of the “average” men and women. None of us are “average,” of course. The OR tie-in here is that the who, why, where, and when are important for understanding why congestion happens at certain times. The network structure is also important, as traffic network is reflected in trip chaining, and it sheds light on what parts of the network will experience the worst congestion. Vanderbilt’s writing on this topic suggests that encouraging people to contribute less to congestion is challenging, since there are many constraints on women’s driving patterns, and as a result, they might not be able to respond to incentives for reducing the amount they drive.

why women are (sort of) responsible for traffic congestion | Punk Rock Operations Research

 

I wonder if traffic light timing has a significant effect on congestion as well. here in MA one light goes green as the next one goes red so you get to go a couple of blocks before you have to stop at the next light. In El Paso where I grew up the lights are timed so if you go the speed limit you see each light turn green as you get to it. May be difficult when there are lots of cross streets but with computerized control you should be able to control the lights to keep traffic flowing rather than stopping for every light.

 

It does, especially if done poorly. Traffic engineers generally want signals everywhere, and politicians sometimes have them installed to serve a local constituency. Speed bumps, which are a popular "solution" also decrease speed (which is what they want) but increase noise from people slowing and speeding to and fro. The signals are getting a lot smarter, so it is more common to se them synchronized now, which helps the major flow of traffic (but is more of a pain if you are going cross-traffic).

 

Speed doesn't cause traffic congestion, bad driving does.

 

My biggest complaint about driving in Atlanta for the last 17 years is the extremely poor management of traffic signals:

Lights that stay green for too long, or red for too long. Lights that turn red for no reason. Lights that are not synchronized at all with neighboring lights. Left-turn arrows that operate when not needed. Left-turn arrows that should be there but aren't. Single left-turn lanes when two are needed. No right-turn lanes when they would be beneficial. "Walk" signals that operate when not needed. And so on.....

 

YES, That would solve much of it.

 

I am interested how newer vehicle technology influenced this graph. I would expect the U to be quite a bit wider with newer braking, tyre and suspension technology relative to 1964-1968 .

And yes, higher speeds would solve some types of congestion, as long as accidents can be avoided. On a part of the city ring around Amsterdam they recently reduced speeds to 80 from 100. The flow of traffic has worsened a lot.