Re-Institute National 55mph?

[groar]

In France some local speed limitations are lowered from time to time with the first goal of making the traffic with less waves and jams.

I do not have the numbers for these specific points, but these are mainly points where speed differences are important between slowest and fastest cars and so generate "waves", slowing down the traffic. By slowing down the max speed, you lessen the speed differences and diminish the waves which accelerates the mean speed.

An excellent document is here : SCIENCE HOBBYIST: Traffic Waves, physics for bored commuters

In Germany several experiments (no reference, from memory) on highways showed that the more people are using cruse control, the faster is the traffic. The explanations were confirming the trafficwaves.org document.

Have fun,

Denis.

[jamesqf]

Originally Posted by dcb

Is yours a typical vehicle? Is this an instantaneous reading or a real one?

No, it's not typical: it's a Honda Insight :-) The readings are instantaneous, but I can hold them for miles if the conditions don't change.

But except for the lean-burn capability of the Insight engine, the same principles should apply to any car. All the instances I gave are from when I was running on gas only - I'm not using the hybrid system to give false impressions, in other words.

[xbUser]

Originally Posted by webshowpro

[*] Intelligent stop lights - that sense traffic to minimize time spent idleling.. Perhaps have people manually monitor lights and control them during peak times. Most cities have traffic centers anyway.... Think air traffic control - the controllers could probably control the flow of several lights, their job would mainly be to "tweak" the timings if they see too large of backups starting to form. communication with specific drivers would also be kinda cool either through mandated radios or through large signs... "TYK-765 merge right and speed up 10MPH"

I've seen some traffic lights have a count down meter. It shows how many seconds green will turn red, or red will turn green. That is very helpful to time the light. All cities should upgrade this.

[NeilBlanchard]

Hi,

In England, about 2-3 seconds before the light turns green, the yellow light comes on along with the red light, to let everybody know. They all put their cars in gear, and/or release their handbrakes and when it turns green -- they go! About the first 5 to 6 cars all launch at once; which really helps get more people through the light on each cycle.

Driving there really spoils you.

[cfg83]

groar -

Originally Posted by groar

In France some local speed limitations are lowered from time to time with the first goal of making the traffic with less waves and jams.

I do not have the numbers for these specific points, but these are mainly points where speed differences are important between slowest and fastest cars and so generate "waves", slowing down the traffic. By slowing down the max speed, you lessen the speed differences and diminish the waves which accelerates the mean speed.

An excellent document is here : SCIENCE HOBBYIST: Traffic Waves, physics for bored commuters

In Germany several experiments (no reference, from memory) on highways showed that the more people are using cruse control, the faster is the traffic. The explanations were confirming the trafficwaves.org document.

Have fun,

Denis.

Thanks for finding this. I was thinking of this guy but I lost the URL. In addition to the experiments in Germany, I want to see more urban planning/transportation studies that quantify this.

CarloSW2

[NeilBlanchard]

Hi y'all,

Yes, that is what I heard on Scientific American Frontiers show, about an MIT traffic study. If everybody accelerates hard and then has to come to a stop, a lot less vehicles get through, than if everybody moved slow and steady -- ecodriving not only saves gas, it improves traffic flow.

An interesting thing happens if there is a stoppage, like an accident -- well after the stoppage is cleared out, the traffic slows down for a long while afterwards; and this "wave" moves backwards away from the place where the stoppage occurred. Sometimes it moves miles away -- these are the curious ones when you can't see anything wrong, and you shake your head and get going again.

[xbUser]

I agree. Steady flow on freeway is not only faster, but also easier to predict the travel time. so, we can go to work on time easier.

Also, I know there is another study says 55mph and 65mph is optimized for traffic flow. Setting the upper speed limit higher would not increase traffic flow because vehicles will reserve more space between themselves at higher speed. At one point, traffic flow may even lower.

I don't agree lower the speed limit to 55mph. If the gas price getting lower, we will hear another voice to raise the limit again. Policy should not change all the time.

However, I agree speed limit should be forced strictly. I know, some place outside America, police gives ticket even 5mph over the limit. We need something like that. Speeding is illegal, break the law. We should stop that. Law should protect people who follow it. For that reason, they should raise the speed ticket triple the amount and increase the penalty. Send more highway patrol to earn more money!! so the state government don't need to cut the medical and education budget. hahaha......

[trikkonceptz]

Speed limit, the term is harsh and absolute. We as a society are to dumb to figure out what a comfortable hwy cruising speed is. The signs should read;

Hwy speed = 55
Speed Limit = 65

That way people realize that 65mph is not the steady target, but the fastest you can travel on this road. If hypermiling has taught me anything it has taught me self discipline and that I am in "control" of my vehicle, the signs around me do not control me.

[tjts1]

I like the idea but I would change it a bit.
Minimum speed limit = 65. Slower traffic keep right.
Highway speed should display actual radar gun measured speed of the average speed between multiple samples updated constantly.

[Twerp]

Originally Posted by trikkonceptz

Speed limit, the term is harsh and absolute. We as a society are to dumb to figure out what a comfortable hwy cruising speed is. The signs should read;

Hwy speed = 55
Speed Limit = 65

That way people realize that 65mph is not the steady target, but the fastest you can travel on this road. If hypermiling has taught me anything it has taught me self discipline and that I am in "control" of my vehicle, the signs around me do not control me.

Around New England, there is a speed limit of 65 with a minimum speed limit of 45 on many highways. In an ideal world, that would tell drivers that they had to stay somewhere between those two speeds and going slower or faster would result in a ticket. In that world, I would be pretty safe from being mowed over while I was doing 55. Other traffic by doing an actual maximum of 65, as opposed to 80, would lower the demand and therefore the price of gasoline (even if it is only by 10% or whatever). In the real world, everybody just does 75 to 80 and gets away with it.

So I guess the key is brutal enforcement, which may be in the works. The route I take to work is just a long back road with speed limits between 30 and 55. In the past couple of months, speed limit enforcement has been pumped up incredibly. In each direction, I can expect to see at least 3 or 4 cars pulled over and there are plenty more speed traps waiting for the next victim. I know that I've learned to love the speed limit on this road because going that speed keeps me out of trouble. I feel bad for the poor schmucks that don't seem to get it. Oh well, maybe at least the town budgets are being met (somebody has to pay for all the snow removal last winter).

So my vote is to have a range that encourages travel at 55 rather than a limit of 55 on the highways. I even support raising the speed limit on back roads to a range between 30 and 40 instead of a limit of 35. Strict enforcement should abound, be it photo cops, pursuit cops or (dare I say it) mandatory governors on all vehicles. Maybe each car should have an emergency mode which would allow you to break the speed limit in times of... well... emergency. But if you don't file legitimate emergency paperwork afterward, you get a ticket.

Speed definitely isn't the only way to decrease demand, dependence, consumption and price of fuel. Sure, there may be many other, more effective ways, but any hypermiler will know that better economy is achieved by improving it with lots of little changes. That's why we often combine strategies to get the mileage we get. Reducing speed is just one of many things we need to do as a nation in order to get back to and maintain cheap gas. As said before, it's a low hanging fruit, ripe and easy to pick.