Drivers behave as if gas is cheap

Very little money was put into 55 mph speed limit and it was hugely effective in lowering oil use and lowering auto accident rates.

 

http://www.policyarchive.org/handle/10207/bitstreams/9284.pdf
Lost time, extra police, police doing speed enforcement instead of practical work like stopping drunk drivers, wasted money on radar detectors and cb radios

It probably is of the order of $100B in today's dollars. Estimates are it saved 0.5% of gas, but that maybe high. If instead of 55, the epa had added highway speeds in there tests in the 1980s,then cars might have been designed to be efficient at speed.... well relatively I would say we used more gas not less compared to smart policy. Educating people about properly inflated tires and driving technique would have saved much more gasoline.

At the time the speed limit was repealed, the IIHS predicted that we would have 400 more deaths a year. The link above projected that fatalities would drop if we switched to doing things like drunk driving arrests. Well the stats are in, the latest I can find are 960 deaths from speeding in 2009 on roads with raised limits. That is far bellow any year that the speed limit law was in effect. Those law enforcement officiers did switch to dui patrol, and over all fatalities per mile are much much lower than in the 55 mph era. Like prohibition it was a bad idea, and the proponents will continue to believe it was wonderful. We do have statistics and history though.

Just an example of one of these clueless proponents
55 MPH Speed Limit Makes Economic, Political, and Environmental Sense - US News and World Report

When you are a idiot mouth piece its important to say the estimates of the past He expects much higher fatalities than 4000 extra on these roads where speeds were increased. Instead fatalities have fallen, and speed related fatalities on those roads are less than 1000. Its simple physics really. When you want to advocate a failed policy, its important not to look at the statistics Raising the speed limit did not reduce fatalities on those roads though, it just did not greatly increase them as predicted. Only a slight uptick once people got used to the new speed limits. At the same time it moved traffic to these safer faster roads, reducing fatalities. Other things then worked on the system as a whole.

 

It is also important to neglect any mention of other factors, like increased safety systems in new cars.

 

And I thought I did Certainly ABS, air bags, higher percentage of seat belts in use, fewer drunk drivers, have reduced fatalities on these roads. Cell phone use and SUVs have contributed to higher fatalities.

The theory also goes that traffic would flow better with higher speed limits. Differences in speed, along with weaving and tailgating behavior, make these roads more dangerous. We do have statistics on how bad it was before the limits were raised, but I don't have statistics for now.

 

Does it? See: http://www.dssl.tuc.gr/en/members/kosmatopoulos/JournalPapers/29.pdf

 

Most likely they do it because their cars don't have an 'in your face' instantaneous MPG display like the Prius has. If their cars did have that display- they'd see the results of their actions- and perhaps modify their behavior... maybe?

 

That is about variable speed limits, not about flow with 85 percentile speed limits.

It was estimated in NY state at the end of 55mph, many of the now faster roads were 5 percentile, that means 5% were going at or bellow the speed limit. On the safest roads, moving it up to the traffic most people flow at should decrease in theory the standard deviation - the differences in speed. I haven't seen studies on the majority of interstate highways whether this theory is true or not. We haven't seen the studies because fatalities did not go up in a statistically significant way when the speed limits were raised. In other words the IIHS had no incentive to pay for a study that would likely show the opposite of their position.

The autobahn with well trained and well behaved drivers is a great example of people choosing the appropriate speed. This requires that roads are built well, and people are well behaved. We have one highway in austin I35 taht was kept at 55mph, because on ramps an off ramps were not built properly for merging at high speeds. The other highway mopac, is 65mph, and safer, because intrisically the on ramps and off ramps are designed correctly. There are fewer accidents and better flow on mopac. It is also unlikely you will get tailgated on the highway, but you will get passed on the left.

 

Vs the "lost time" of 22 years of continuous oil wars, the $15T wasted, the hundreds of thousands killed and maimed, the millions displaced all because US didn't stay with 55 mph speed limit and other proven means to cut US oil use.

And of course we do need to keep in mind that traffic enforcement is a huge source of net revenue to police departments everywhere.

 

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We haven't seen the studies because fatalities did not go up in a statistically significant way when the speed limits were raised. In other words the IIHS had no incentive to pay for a study that would likely show the opposite of their position.​

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And you know that how ? Fatalities are multi-factorial, influenced by driver, roads, car, rules and other drivers. It takes a large and well designed study to separate out the variables.​

It may be true that IIHS was not motivated to drop the fatality rate further, but that hardly proves that increasing the speed limit is not a cause of increased fatalities. By the way, IIHS is funded by car insurance companies. They are interested in accident and fatality prevention as in relates to costs, not loss of life or maiming per se.​

 

Yes, but if you read the graphs you will see that they compare traffic flow at various speeds, and that 60 often beats 75. This contradicts your hypothesis.

 

I don't know how. Roads have capacities. If the road is over capacity, then lower speed limits increase capacity. The speed limit of a road should be set with this in mind. The 85 percentile rule of thumb is just one of the heuristics. This is one reason speed limits on interstates drop as they enter a congested city, at least they should drop if speed limits are properly set.

 

Well the speed limit on the highway around downtown LA is 55 as well as the I-10 going through Phoenix and traffic seems to flow but on ramps and exit ramps contribute to the congestion.

 

The flow changes as you add interference to the flow, much like fluid dynamics. Put X hundred cars on a 4 lane free way in the middle of Montana, and you would have one flow rate per mile. Put the same number of cars in downtown anywhe, with ramps, merging on and off, and the flow rate would drop.

That same flow rate through Montana would change if you mix in vehicles of different speeds. If everybody is going the same speed, a road at 100% capacity would flow fine since there is no advantge to change lanes (and therefore impede flow) but mos in diffent speeds and the over all rate goes down.

Traffic dynamics are a very complicated thing. Just watch a slow moving traffic jam on an interstate. People jockey for lanes, back and forth, (slowing down the over all flow) track those same cars at the end of the jamb, and they may be a few hundred feet (or a few thousand) ahead of the cars they passed at the beginning, but everybody else is a bit slower. If everybody just stayed in thier lane,, everybody would go faster. (not withstanding lane closeures etc).

Another interesting study is who moves faster when the is a jamb due to a lane closure. I contend if every one mergedinto the open lanes ASAP, everyone would move faster in the net. As it is now, a few benefit by waiting until the last instant, while the rest pay the penalty. If we would ticket those late mergers for negligent driving then perhaps people would learn to be better drivers.

Icarus

 

That makes it worse as people pick different spots to merge.

Best is cars merge alternately and smoothly at the last possible spot. It is the fastest, most organized and fairest way to merge

Person to ticket is the one who doesn't go with the alternate merge to save a car length.

 

Someone (on cleanmpg I think, will try to find it) was advocating always leaving a generous space in front of you. If someone wants to occupy it, so be it. I believe his rational was that bunching up, with the inherant slow-down-and-speed-up, was slowing everyone. I would think anything that avoid a decel/accel would improve mpg.

 

^^ Hobbit is an advocate of that approach, and I think he has good data and analysis to back it up.

 

I too find it less stressful, and far safer, to leave lots of car lengths in front of me, allowing people to come in and out at will. It distresses those behind me to to see this, even though we're all, including the vehicle ten lengths in front of me, going the identical speed. An additional consideration is that as I age, extra stopping distance is not necessarily a bad thing. It also enables me to stop gently enough to allow the tailgater sufficient time to also stop safely. (I allow sufficient stopping distance for almost two cars.) I don't see a safe alternative. If I keep the one to three car lengths the other drivers prefer (even at 50-60 MPH), there is no way I can avoid a rear-end collision in a panic stop. This is something I learned while commuting on a motorcycle and the goal then was self-preservation since that was a "stone hitting the pitcher" situation.

 

The same thing crosses my mind. I'll increase my buffer to the guy in front if the tailgater get's closer. Two benefits: the aforementioned safety factor, and maybe he'll be tempted to change lanes and get the f*** in front of me .

It's pretty sad. Up here for example we have graduated licenses, and Novices have to have a Green N sticker on their backside. You'll often see someone with an N compulsively weaving in-and-out of traffic, in a vain quest to get somewhere fast. There's a fair share of non-N drivers doing the same thing. They singlehandedly endanger the rest of us, and it seems little is done to crack down on this: it's too subjective a behaviour to catch a ticket.

 

I wouldn't want the law pulling over people weaving in traffic jams, that will just make things worse. It would be nice if the novices would learn to drive better though.

 

Sometimes I mull on how hard it would be to put an EMI generator behind the rear bumper facade. With beam steering, narrowly focused on the following vehicle engine compartment . . . Of course that also means I would never be pulled over by a following police car.

Bob Wilson