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Raise the Speed Limit June 16, 2006

Posted by federalist in Regulation, Social Politics, Transportation.

You can run with the herd your whole life and never get caught. The odds are in your favor, but if a predator is on the prowl someone will get taken down. It might be you. Life on the plains, or reality on America’s highways?

Everyone knows that on a clear day the flow of traffic on a modern highway is far in excess of the posted speed limit. Which raises the question: What is the point of our speed limits if nobody follows them?

The cynical answer is that speed limits exist to generate revenue. If everyone thinks it’s reasonable to drive 75, set the speed limit at 55. When local government coffers start to dry up, send the police out with quotas: Pull cars over until they’ve written enough tickets to fund the next quarter’s budget. It’s a negative lottery that everyone seems willing tolerate.

Why don’t people get tired of paying taxes this way? Unfortunately there are also plenty of nanny groups ready to argue against raising the speed limit because “speed kills.” And we can’t argue with that. Lower speeds would almost certainly result in fewer fatalities.

Of course, if we want to eliminate highway fatalities we should set the speed limit at zero. But our society is willing to tolerate some risk. After all, we allow people to consume alcohol even though it is routinely abused and directly contributes to horrific drunk driving deaths. We allow people to dig swimming pools even though many children drown to death in them. We allow people to build tall homes and buildings even though people die falling from them. And we allow people to operate motor vehicles at speeds that can kill.

Motor vehicles can be deadly at any speed. Every marginal increment in the speed limit increases the potential danger. So there will probably be more fatalities if the average speed on a road is 65 than if it is 55. But if 65 is unacceptable, than why is 55? 45 would be safer, and we would save even more lives by forcing everyone to amble along the freeway at 35.

Where does that magic number, 55 mph, come from? In the 1970’s fuel crisis the government seized the initiative. At the time many cars achieved maximum fuel efficiency at 55. But not many 1970’s-era cars are still on the road. Today’s cars have transmissions with taller gears, capable of efficient cruising at higher speeds. Modern cars are also more aerodynamic, and incorporate more standard safety mechanisms than were available in any car from a generation ago. Furthermore, modern highways are much safer, with extensive energy-absorbing guardrails and energy-deflecting center concrete dividers. If 55 was safe and efficient a generation ago, then a speed of comparable safety and efficiency would be significantly higher now.

Evidently the vast majority of motorists feel justified driving faster than the official speed limit. This informal speed consensus varies with the road and conditions but, as anyone who drives today knows, it often reaches 85 or 90 mph on the best highways. Is that unsafe? Well, it’s less safe than going 70 and more safe than going 100. In any case, it is not without precedent, since many foreign countries sanction the operation of passenger cars at those speeds.

The question all of these American speeders must be asking is, “Why do we maintain this charade of a speed limit?” That convoy of cars cruising along the left lane of a 3-lane divided highway in clear weather at 85mph shouldn’t feel obligated to slam on the brakes when passing a police cruiser. Speed should not be used as a surrogate for safety. Highways would be much safer if police concerned themselves exclusively with the reckless drivers – those weaving through lanes without signaling, tailgating, or obstructing the flow of traffic in passing lanes.

Drivers or cars uncomfortable at higher speeds should stay out of the left lanes. Commercial vehicles and trucks should also be held to tighter limits, in recognition of their greater mass and reduced maneuverability. (In Europe, commercial vehicles are individually certified for specific speeds, and they must prominently display those speed limits on stickers.)

As anyone who has driven in Europe knows, rules like the ones suggested here produce highways that are safe enough for most people’s comfort. It’s time we ended the charade and set reasonable speed limits on our highways.


1. federalist - July 7, 2006

WSJ today provides more ammunition for this argument: http://www.opinionjournal.com/editorial/feature.html?id=110008621

2. federalist - February 22, 2007

Makowsky and Stratmann have an interesting paper with plenty of evidence that speeding tickets are a revenue-generation mechanism, not a public-safety mechanism. From their abstract:

[W]e study the political economy determinants of traffic fines. Speeding tickets are not only determined by the speed of the offender, but by incentives faced by police officers and their vote maximizing principals. Our model predicts that police officers issue higher fines when drivers have a higher opportunity cost of contesting a ticket, and when drivers do not reside in the community where they are stopped. The model also predicts that local officers are more likely to issue a ticket when legal limits prevent the local government from increasing revenues though other instruments such as property taxes. We find support for the hypotheses. The farther the residence of a driver from the municipality where the ticket could be contested, the higher is the likelihood of a speeding fine, and the larger the amount of the fine. The probability of a fine issued by a local officer is higher in towns when constraints on increasing property taxes are binding, the property tax base is lower, and the town is more dependent on revenues from tourism. For state troopers, who are not employed by the local, but the state government, we do not find evidence that the likelihood traffic fines varies with town characteristics.

3. federalist - March 14, 2007

An article referenced in my post here notes:

[I]n most European countries the highway speed limit is either 75 and 80 miles per hour. Britain, Latvia and Sweden have the strictest speed limit with 70 mph, according to an official EU Web site.

4. Experts Agree: 165 MPH is a safe speed limit | Federalist - September 4, 2014

[…] There’s no guarantee you won’t be in a collision if you drive on public roads, no matter what precautions you take. So society, via engineers and legislators, weighs costs, benefits, and risks and reaches designs […]

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