Be Safe, Break the Law

The 55 mph speed limit was a vain attempt by the Federal government to reduce gasoline consumption; initially passed in the 1974 Emergency Highway Energy Conservation Act the law was relaxed in 1987 and finally repealed in 1995 allowing states to choose their speed limits. Highways and cars are safer today than in the 1970s and on many highways speed limits were increased to 65 mph. Higher speed limits are often safer because what is worse than speed is variable speed, some people driving fast and some driving slow. When the speed limit is set too low you get lots of people who safely break the law and a few law-abiders who make the roads more dangerous.

Unfortunately vestiges of the 55mph limit remain, in part because police like the 55mph limit which lets them write tickets at will whenever they need an increase in revenues. John Carr at the National Motorists blog gives a particularly egregious example from Massachusetts:

The speed limit on Route 3 is 55. The speed limit used to be 60….It was reduced by executive order in 1973 to comply with the national speed limit. When the national speed limit was repealed in 1995 the highway commissioner ordered the low limit retained…

It gets better. Route 3 was completely rebuilt a decade ago. The design speed for the project was 110 km/h (68 mph). The design speed is like a warranty: nothing in the road design requires a driver to go slower than 68 mph, not even on a wet road at night (the design conditions).

The average speed is not far from the design speed. The 85th percentile speed, which is supposed to be used for setting speed limits, is around 75 mph. A little over by my measurement, which found 1% compliance with the speed limit.

Eventually the absurdity of the 55 mph speed limit sunk in and in 2006 MassHighway traffic engineers recommended a speed limit increase. State Police vetoed the change, preferring the 99% violation rate that let them write tickets at will. Police have no legal role in setting speed limits. Somebody in the Romney administration weighed the risk of losing ticket revenue against the risk of being blamed for accidents. Police won.

After engineers lost that fight people began to worry about the high accident rate on Route 3. The state hired a consultant to do a Road Safety Audit. The consultant’s report blamed the low speed limit, among other factors, for the high crash rate. The report explicitly recommended raising the speed limit.

Three years later, state officials have not followed the advice of their engineers, their consultant, or 100,000 drivers per day. State police are still out there running speed traps and helping keep the road as dangerous and profitable as they can.

Hat tip: Radley Balko.


Do you really think that states increasing their speed limit to 65 eliminated "variable speed"? Every time I drive on a highway says otherwise.

It would certainly lessen it. The Ohio turnpike just went up to 70 mph. Traffic was already doing that, so there were not too many changes, except those who would keep the speed limit sped up a bit - less variable speeds.

"A little over by my measurement, which found 1% compliance with the speed limit."

That 1% causes other drivers to slow down, change lanes, and pass. So that 1% has a cascading effect on congestion and safety. On a 3-lane road, that 1% causes the entire right lane to slow down (that's 33% of lanes), and the adjacent lane is slightly slower because cars are entering that lane after slowing down so they can pass on the left (now we're at 66% of lanes effected).

I'm in the UK and have to agree with everything here. We have a 70mph speed limit on motorways (highways) and some dual-carriageways, yet the rest of Europe has a 120kph speed limit, which i believe is around 83mph. I've driven across Europe (15 countries in total) on two occasions now. Both trips i saw no difference in driving style and dangerous occurrences when driving at the higher speed of 83 compared to 70mph. All that happens is you cover greater distances in a shorter amount of time; its that simple.

Also forgot to mention how i can't believe a country as big as the US has such a low speed limit, despite the advancements in construction of vehicles and the high safety targets they have to reach. We need to invest more in pedestrian awareness. I can only speak from personal experience and from speaking to others but 9/10 times it's the fault of people blindly walking or trying to quickly get across a road that causes drivers to take action and could end up causing an accident.

@Rob Breckles One of the ways to increase road awareness (including pedestrian awareness) is by taking a non intuitive approach; give right of way to merging traffic and traffic entering from side streets. This makes people more aware of what is happening either side of them and makes them more likely to slow down at intersections (the most likely place for collisions).

And unfortunately, plenty of those slower cars are in the passing lane(s). That, too, is dangerous causing considerable congestion.

The problem with judging this by your experiences while driving is that you are going the same speed as everyone else going that speed and therefore you are only aware of the other drivers directly around you (which you might deem as "safe"). These seem like relatively few drivers. You are also aware of people going faster than and slower than you because either you overtake them or vice versa. These seem like a disproportionately high proportion. You don't see the many, many cars that are (1) going your speed and (2) far in front or behind you. To get a true measure of the proportion doing a common speed, you need to measure from a stationary position on the highway.

If state and local governments want people to drive 55mph (and they should -- lower speed saves lives), they should through better road design. Study after study has shown people will drive at whatever speed feels safest. Designing a road to accommodate 75mph traffic and then setting a 55mph speed limit is ineffective for anything other than police ticket revenue.

There's nothing wrong with collecting revenue from motorists per se. In fact, I think that police officers should start collecting fines from motorists for "driving on a congested road". It would be cheaper than setting up universal congestion charges.

Yes, because you always know the highway is congested before you enter it.

Because obviously there are always perfectly viable alternate routes and people choose to take the more congested ones...

Yes, the answer is to build poorer roads. Are you a state of federal employee?

Come on, "tom", be fair. Michael is not saying that. He's saying if you build a road that is designed for people to drive fast, they will do so. If you design a road for people to drive safely, they will.

The snide comment about being a state or federal employee is insulting and base, and reflects poorly on you personally.

I think Michael is saying that roads should be built to feel dangerous at speeds above 55mph.

Alternatively, we could mount javelins on steering wheels.

When discussing freeways, a road which is designed for fast driving is a fundamentally safer road than one which requires slower speeds. The features of roads that require slower speeds are blind corners and hills, lack of a shoulder (or lack of a hard shoulder), complicated merges, sharp corners, potholed surfaces, toll booths, and forced merges. Each of these features REDUCES the safety of the road, which is why you have to drive slower. If one highway has an average speed of 75 when uncongested, and another has an average of 55 when uncongested, the latter will be a much more dangerous highway.

Driving 90 on a straight, flat, highway with a shoulder and clear visibility for a mile in either direction is much safer than driving 50 on an urban highway like the Cross Bronx Expressway. They shouldn't be treated the same.

Peter H.

Safety of urban freeways is much safer than rural freeway and roadways (Based on fatalities per 100 million vmt). The elements of the road that you discussed do provide safety, but congestion reduces the speed and therefore the kinetic energy in cars that is a signifcant factor in deaths in crashes. Another factor in safety is the number of people on the road. For 30,000 people a day per lane using a facility provides more revenue and public justification for providing all the roadside safety features you discuss. On a rural country road with 50 cars a day per lane it is hard to find the money and convince people that safety improvements will provide a return on the investment. The active driving that required on urban roads to avoid other vehicles heighten drivers awareness more than the many time monotonous rural driving. That is why the fatality rate for rural non-interstate roads is over 5 times higher than the urban freeway fatality rate. Congestion and volume increase safety.

Come on? Sounds like you want to believe that a slower road isn't actually a more dangerous road.

lower speed saves lives

Do you have evidence to support such a bold assertion? The rise in speed limits resulted in a fall in motor vehicle fatalities.


These guys provide serveral references.

Speed is a relative, therefore if a speed limit decreases the average speed but increases the differential speed between vehicles you have the following results. 1. Your accident risk relative to the fixed objects along the road is reduced. 2. Your accident risk to vehicles relative to vehicles with differential speed increases. The studies are saying that the diffential speed decrease safety more than the decrease in average speed.

Do you realize the only study present shows that raising speed limits here would decrease crashes?

Connecticut is doing that by leaving the potholes unfixed.

You are right, they should just rebuild all the roads. What a brilliant suggestions. Because people are too stupid to follow simple rules, they need to be built a cage which forces them to decide.

If a vehicle going 55 is an unsafe obstacle, there's a problem. There are plenty of 0 mph hazards that a driver may have to deal with.

Completely stopped cars often seem to be a problem.

Can you explain the mechanics of a "partial stop"? I keep seeing this "complete stop" stuff, thus it makes me wonder.

The 0 mph hazards don't change lanes suddenly.

On route 3 during rush hour completely stopped cars are frequently encountered.

The dark side of Pigovian taxes…

Put this in the column of cons for a carbon tax, not that it outweighs the pros.

'Higher speed limits are often safer because what is worse than speed is variable speed, some people driving fast and some driving slow. When the speed limit is set too low you get lots of people who safely break the law and a few law-abiders who make the roads more dangerous.'

As always, it is instructive to consider how the (technically) non-speed limit sections of German autobahns works - trucks not allowed to go faster than 50 mph (and finding a truck doing 60 mph is quite rare), busses generally don't go faster than 60mph (70 mph is quite rare) while cars are going anything from slower than trucks and busses to over 150 mph.

(Cynical note - in my opinion, the last stretches of unlimited speed autobahn in Germany will be the ones found between Frankfurt and Stuttgart - particularly the A5 is well suited for extended high speed stretches, and it is among the most convincing sales arguments a certain pair of German car makers can make to a group of people who may want to pick up a couple of performance machines before flying them home on the jet.)

Strangely, no one here attempts to argue either of the following points made above, since variable traffic speed is a given, and as there is nothing but a technical guideline concerning speed limits for cars on the non-speed stretches, while trucks in particular must follow a rigid speed limit which can easily be 3 times slower than cars passing them, everyone driving a car is allowed to make their own choice as to the correct speed - up to the point their vehicle can't go any faster.

Maybe the difference lies more in the quality of the drivers? Among other things, of course, but that just leaps to mind when reading something like this.

In the stories I've heard from friends driving the Autobahn, they always talk about how the local in their passenger seat repeatedly pleads with them to drive faster to not irritate the demons approaching from behind. And something about getting only one taillight flash to get out of the way.

Wow, lets all refer to stories we have heard, there is bound to be lots of bullshit insight on there.

The fact is most drivers in the USA are morons. That is what someone told me, anyway.

As a US driver, I suggest that you were told correctly. The amount of drivers I see pulling stupid stunts like making unsignaled left turns from the right-turn-only lane or blowing through stoplights makes me amazed that the number of accidents here isn't much, much higher than it actually is.

It is my understanding that the difference is that each speed zone is dependent on the lane. For example the right lane would be where the slow moving trucks and busses drive and the left lane is where the high performance cars do 120 mph (or the kmph equivalent). Thus the speed in each lane or zone is not variable.

So for example if you went slow in the fast lane you would get a ticket for driving too slowly. A car doing 60 in the 120 lane is the equivalent of a car at dead stop on a highway with a 60 speed limit. Very dangerous.

So there would, in theory, be less speed variation on the autobahn because of this. I have observed in America that most cars like to go around 70 mph on the expressways, but there will be always a few cars doing 55 in any and every lane, causing the fast cars to slow down and go around the fast cars and speed up, which always struck me as dangerous.

If anyone from Germany can comment on the autobahn, please correct me if I am mistaken.

It is mixed in terms of how lanes are enforced - for example, on the 3 lane stretch on the A5 between Waldorf (SAP headquarters) and Karlsruhe, trucks and busses are completely free to use the middle lane also (and often do). The left lane is reserved for high speed traffic, and while trucks and busses do not meet that requirement, many cars don't either - which doesn't stop some car doing 55mph or so from moving into the left lane to pass the slower vehicles in the right two lanes.

On other autobahns, such as in the Pfalz, trucks are forbidden from passing - leading to literally kilometer long columns of trucks moving back and forth from the harbors in Belgium and the Netherlands. Of course, generally such autobahn stretches also have an enforced speed of around 80mph, which is often not possible to drive, since the autobahn is effectively only a single lane for higher speed cars.

The variation of speed between the slowest and fastest vehicle on a German autobahn may occasionally be twice a customary legal speed limit on a U.S. interstate - truck doing 50 mph, Porsche hitting a good 170mph, both on the generally straight and flat A5 stretch between Bruchsal and Karlsruhe. And there is no question the Porsche driver is being an idiot in such cases - along with the other high performance vehicle owners trying to meet or beat that speed. Though as many people will note, a Posche can't go any faster than the vehicle in front of them, and a lot of the time, the A5 is much like I95 - the main commerce and vacation route for tens of millions of people moving north and south.

I think on most Autobahn's it really becomes work, if you want to go above a moderate cruising speed of 90 - 100 mph.
But most people are used to get back to the right lanes when possible. But on the some less popular stretches in the South, off rush hour, 120 - 130 mph is beautiful and safe. And I think many Germans actually do like to perform a kind of discipline in this, taking into consideration also the interests of those behind and left of you as well as those in the right lane.

An example:
Lets say you have a meeting at 9 in the north of Munich, 500 km or 300 miles away. With a 65 miles speed limit, taking variation and construction sites into account, 6 hours minimum, get out bed at 2 o clock, and tired at arrival, driving 3 or more hours in the dark. Probably you will take a hotel room and wast half a day on the day before.
With 180 km/h, it takes 3.5 - 4 Hours, out of bed at 4:30, a coffee at arrival, no problem. It cuts costs, especially time by half.

If you do not want to drive faster than 60 mph, why use the Autobahn ? Take the local roads with a speed limit of 60 mph, its more scenic. If you cant stand the heat, get out of the kitchen.

The left lane is not meant for fast driving per se. The purpose of the left most lane is actually to get in front of the vehicle(s) in lane 2, meaning you have to switch back to lane 2 when it's reasonable to do so. Also, the difference in speed between your car and the car(s) you are meaning to pass has to be greater than 10 km/h. As you can see from those two rules, there is no special speed limit for the left lane, and if you are meaning to pass some cars going 70 km/h in lane 2, you only have to drive 80 km/h or more in lane 1 and move back to lane 2 when there's some distance before you will encounter slower driving cars on lane 2 again (else you may just continue your passing maneuver). Cars behind you even have to keep a reasonable distance between their car and yours, so you are allowed to finish your passing maneuver even if you are driving pretty slow compared to the rest of people making and continuing their passing maneuvers on the left lane.

Wikipedia also has an article about German autobahns, listing some additional rule clarifications.

Ive done return trips across Germany twice. So 4 times i've been on the Autobahn and basically how it worked so simply was that you had trucks in the slow lane, anything going fast enough to need to overtake the trucks in the middle lane and then anything wanting to go flat out, in the fast lane, it was that simple.
What it comes down to is the amount of drivers with a lack of common sense. You check your mirrors for stuff approaching and move over if its approching quickly. Its a case of stay on the slowest lane you need to until you need to overtake. If everybody did that, there would be no problem but people dont, they hog the middle lane. THATS the biggest problem on a motorway (highway/freeway).

But my understanding is that the no-speed-limit Autobahns (with their high and highly-variable speeds) are NOT very safe -- which is why speed limits have been imposed on nearly all of them (and that the only reason it did not happen sooner was because of the country's financial interest in selling powerful luxury cars).

Well, actually, noise abatement liked played the larger role in the last 15 years in terms of creating autobahn speed limits.

One point about the German autobahn is that unless you are passing another vehicle you damn well better be in the right hand lane. On California Interstate roads such as I-40 with a 70 MPH speed limit you will find 18 wheelers in the right lane going 70 and cars in the left lane going 85. The problem with that is you also find cars in the left lane going 55 or even worse occasionally 45 which is the minimum speed to be on a controlled access road in California.

Arizona is a little more sane about their roads. The speed limit on I-40 starting from the Colorado River is 75 and the DPS (Highway Patrol) generally don’t ticket below 85. I’ve had a California CHP officer near Needles California tell me that he doesn’t ticket below 80. Texas has one stretch of I-8 where the speed limit is 85. People in Texas, unlike people in California tend to stay to the right if they are driving below the speed limit.

During my misspent youth I worked in the traffic control business where we helped cities in California with speed surveys. Roads where the speed limit was adjusted to what 85% of the drivers dove at had fewer accidents. Drop the speed limit and after a shot time the accident rate goes up. This is the same as red light cameras, a source of revenue and precious little else.

W. Price

Agreed about the right-hand (for us, usually center) lane. If you're in that left lane, you can't *believe* how fast another vehicle going about 130 MPH (and they do) can overtake you. Another reason for new speed limits is that there is a country-wide program of road repair, and sometimes you're squeezed into 1-2 lanes. Interestingly, the transition from 3-4 lanes/fast to 1-2 lanes slow is orderly and polite— no one tries to sneak into your lane at the last minute.

A relative said "Well, you Americans are obsessed with guns. We like to go fast."

Please tell me where that stretch of I-8 is. I want to drive to there.

(not tail light, headlight rather)

Great post, reminds me of a video portraying an act of "civil obedience" on Atlanta's I-285 where similarly the speed limit is 55mph with average traffic going in the 70-75mph range.

It's worth a look for those interested:

As an American who has lived for many years in Germany, I find the lack of variation in speed on US highways to be particularly dangerous. I visit friends and family in the US every year, and driving on US highways, with all cars and trucks going basically the same speed, is terribly boring. My mind wanders, and I become inattentive - drowsy even. This doesn't happen in Germany where I am always passing and being passed. I don't know if German drivers are better than US ones (some can be quite rude), but they are more disciplined. Left lanes are used for passing only and otherwise kept clear.

As a German who has lived for many years in America, I fully agree : - )
Speed is a lot more variable on the Autobahn.
Sometimes I took a tour through New York City, before flying back to Germany, in order to get back into a quick reaction mode again.

Pretty sure that in Germany you are legally required to only use the left lane for passing, which is not true in the US.

Also in US highways in uncongested areas you typically also see a large variation in speed.

Maybe the speed limit on Route 3 in Massachusetts should be higher than 55, but are we really supposed to believe that the speed limit is kept that so that the police can write tickets at will? Let's assume that the speed limit was raised to 65. Do you believe that the police would have any difficulties writing speeding tickets to speeding motorists then? Do you think there will be a cop sitting by the side of road going "I just can't find anybody who is speeding due to these new increased speed limits?" Does that make any sense?

It's like alcohol blood limits. Set them way low, then you can breathlessly exclaim "He was going 20 past the speed limit!" or "His alcohol level was twice the legal limit!"

It's more subtle than that. It's like a free option on ticket writing.

Plus, at least in MA, the further you are over the limit, the bigger the fine is. The fine increases dramatically, in fact.

Also it is a lot harder to appeal a ticket when it says 77 in a 55 as opposed to 77 in a 70.

So you really think they are going to have a hard time finding enough people who are going 15 or more above the speed limit? And if this is about generating money for local government, then why is it that even habitual and excessive speeders get speeding tickets only very rarely?

"why is it that even [a] habitual and [b] excessive speeders get speeding tickets only very rarely?"

[b] Because the most excessive speeders are the hardest to catch. Even if speed limits go up to 70, the highway patrol will still have a functionally unlimited supply of folks driving 15 over; they'll just have to work harder to run down folks who are doing 85 in a 70 zone than they would to run down drivers doing 70 in a 55.

[a] Because the causal arrow of habituation to speeding doesn't point in the direction implied by the sentence. Habitually speeding doesn't cause police to leave a given driver alone; police leaving the driver alone causes habitual speeding.

You clearly don't live in Massachusetts...

The un-speed limited German autobahn has a lower accident rate than US interstates and even a lower death rate.

I suppose that if you really want police to be able to write tickets at will, you could just pass a law allowing them to write tickets at will (note I am not in favor of this). Just allow police to hand out tickets for something vague like "suspicious behavior". Weren't there vagrancy laws in the past that worked that way?

They way to have those benefits and actually get it passed into law is to have an unreasonable speed limit and claim it is for safety.

As someone who lives three miles from the road in question, and commutes it every day: I'm not buying it. There is a whole lot of hooey in this story, to use the technical term.

First off, Route 3 is a very long and diverse road, going from New Hampshire to Cape Cod. It's extremely congested in the northern part where I am, due to commuters, and much more open towards the Cape, where everybody speeds to go on vacation. When it says "completely rebuilt a decade ago" they are only referring to the northernmost end of the road. This is where I spent the first 10 years of the 21st century: sitting in traffic due to construction.

1 -- There are very few accidents on this rebuilt road, because everyone is going 30-45 mph due to commuter traffic.
2 -- There are hardly any tickets given out here either, for the same reason.
3 -- Nights and weekend? No, accidents are still rare. Those that occur often have alcohol involved. If you want accidents, check out 93 just east of here.
4 -- There are no speed traps on the weekends, either. For those, visit 495 just south of here.
5 -- I can say with absolutely certainty that since 1997, with all of my complaints about Route 3, that Variable Speed has never cracked the Top Fifty.
6 -- Speed traps are commonplace on the southern end of Route 3, to get the Cape Cod vacationers. I have been a victim of this myself. But it is nowhere near the "rebuilt" section of road. You might as well say that construction on Route 95 in Maine is affecting driving speeds in Florida on the same road.

So, while I agree that the speed limit should be higher (though it has nothing to do with accident prevention), and that the Mass State Trooper Patrolmen Association is among the greediest and corrupt organizations in the USA, this article is in fact hooey.

Please RTFA specifically page 21 of the consultants report

You're talking about two separate roads. MA-3 is the one that goes down to the Cape. US-3 is the one that goes from Burlington, MA into New Hampshire. Carr is only talking about US-3, and he's completely correct.

This reminds me of the old NASCAR debate around restrictor plates. The bad drivers wanted the parity; the good drivers wanted the ability to accelerate away from danger.

If the mass police hand out more tickets to make up for budget cuts in recessions why did the number of tickets issued by the Massachusetts State Police fall by over a third in 2009 when their budgets were cut??

In Massachusetts revenues from traffic tickets issued by the state police go into the general state revenues and account for under 1% of total revenues. The same is true of local town and community budgets. It appears that the police really do not benefit from increased traffic fines. So why would they write more tickets if they do not benefit?.

I agree with the other comments about route 3 from 128 to the NH border. During rush hour no one can speed because of the heavy traffic.

Why write tickets at all then? Tickets per traffic officer patrolling the roads? Do you know that the budget didn't cut the traffic cops? Maybe they should have increased enforcement if they were under-enforcing previously. If you look at big enough aggregates Massachusetts itself is a rounding error, but that doesn't change the micro incentives.

Who said it is only a revenue decision? I suspect they aren't really interested in writing more tickets but in being justified in pulling over anyone to look for drugs, check for outstanding warrants, instigate resisting arrest arrests and the like by having the option provided by full non-compliance. If you were the police and no one required you to enforce the rules (partly because they can't actually enforce unenforceable rules), would you rather have more or less flexibility?

Who said it is only a revenue decision?

From the quoted item:

Somebody in the Romney administration weighed the risk of losing ticket revenue against the risk of being blamed for accidents. Police won.

That is weighing two factors, not just revenue, it's also just two actors the police and the alleged person in the administration. And it sounds pretty reasonable. Raise the speed limit and the next few accidents will be blamed on this. Your reward is (you believe because the police told you) lower ticket revenue. Note that there doesn't actually have to be lowered revenue for the police to claim that because it might just be the most effective claim to make to a bureaucrat. Do we not see that all the time? For example, when they threaten to shut down the government, the people they claim won't get checks are in fact the last people they would ever fail to cut checks to.

In short, Spencer is accusing either the journalist or the police of lying. I don't reject the possibility that they are all lying.

>The average speed is not far from the design speed.

So, increasing the speed limit would raise the average speed higher than the design speed. Somehow that doesn't seem optimal.

First of all the design speed is the "guaranteed safe" speed for any driving conditions. If that is the safe speed in driving rain at night, average speed should be higher.

Second of all, the speed limit is 55 and the design speed 68. Obviously they could increase the speed limit to 65 and be within the design speed.

Sure, they could increase the speed limit and have the speed limit be within the design speed. But with the speed limit at 55, the observed average speed is near 68. Do you think increasing the speed limit would have no effect on real average speeds?

Perhaps they should increase the speed limit and then enforce it in a visible and, more importantly, predictable way. Currently, there's a general understanding in most places that you can get away with 10 over, though you're never sure if you might be ticketed or not, and of course if you get pulled over being cute or making a play for sympathy might get you off with a warning. Raise the limits to something reasonable and then actually enforce it.

Of course, this would be a massive cultural change and so is unlikely to happen or succeed.

Probably only a minimal difference. From my conversations with coworkers, a lot of them quite simply don't have the slightest idea what the speed limit in many areas is. They go the speed they feel comfortable driving. Riding with them to lunch and so forth, I can say they speed in quite a lot of places.

Of course, the ones who actually know they're doing it have the fanciest radar detectors they can buy. Not sure how that skews the sample.

Short answer: yes. Well, very little effect. I recall after the speed limit was raised on Michigan's rural Interstates from 55 to 65, then to 70, the state released data indicating that during the days of 55 the average speed on these roads was about 65. When the limit was raised to 65, the average speed went up to something like 70, and when the limit went to 70 the average went all the way to 72. It's an old wives tale (usually propagated by cops wanting to keep the limit low) that people automatically drive 10, 15, whatever, over the limit. People will drive the speed that feels comfortable, depending on road conditions, weather, traffic, etc.

all the design speed is the “guaranteed safe” speed for any driving conditions.

That sounds suspicious to me. Simply put, there are going to regularly be driving conditions (fog, rain or snow) that will obscure visibility such that cars traveling at the speed limit cannot avoid an obstacle at the limit of visibility. Even with the quotes, this feels like diminishing your case by over-stating it.

Variable speed is the reason why the American Le Mans Series is better than NASCAR. And the fact that ALMS actually uses variants of real cars, as compared to the horribly misnamed "car of tomorrow" they race in NASCAR

Just a few points:

1. Air resistance goes up dramatically and non-linearly with speed. I think you're using twice the gas at 75 mph as you are at 55 mph. Peak oil, global warming, yadda yadda.

2. Kinetic energy goes as the square of the velocity. At higher speeds, collisions with stationary objects cause dramatically more damage and injury.

3. Aren't we supposed to be heading for a future with driverless cars? If you can sit in the back seat being productive on the Internet with your smartphone, does it really matter if you get there half an hour earlier?

What I am hearing here is that we should scrap the speed limit since so many people are breaking it. Should we scrap immigration control for the same reason?

Haven't they found that the Autobahn in Germany is actually safer comparably to the US. Low speed doesn't equal safety.

We've driven all over Germany. First, they have speed cameras. Speeding=ticket, period. Above a certain amount of tickets, you loose your license for 6 months, Keep it up and it's permanent. There are absolutely no police patrolling the roads in Germany. They're too busy addressing, you know…crime. Finally, driving on the autobahn is hair-raising, and any accident is almost 100% fatal.

Let us suppose that Alex is correct in his analysis and that rent seeking by police has trumped efficiency (the recommendation by the traffic engineers) in deciding the speed limit for Route 3 in Massachusetts. Like many other of his blogs, this one illustrates a failure in political decision-making. But on reflection, this blog implies quite the opposite. The blog specifically mentions only the 55 mph speed limit for Route 3, but does say that in other states the speed limit has been raised to 65 mph and higher. So the too low speed limit for Route 3 is the exception rather than the rule. In most other states efficiency has trumped those rent-seekers who would use 55 mph speed limits to gain rents. The importance of rent seeking cannot be established by only reporting cases where it appears to be true. One needs a more systematic collection of the evidence. And in this particular blog, Alex's reference to other states suggests that his particular rent-seeking story is not applicable elsewhere.

You shouldn't have any deep, dark secrets in your past because a criminal background check is required. This is understandable since you will be spending a lot of time with the teenagers of people you probably don't know.

55mph is the best compromise between speed and energy savings, then just increase fuel tax until everybody understand

There are some reckless drivers out there, but I think most people drive what they think is a safe comfortable speed. I live on the east coast, where there are a lot of 55mph speed limits that are regularly disregarded. My wife and I recently took our first trip out west, driving through Nevada, Arizona and Utah. We were on several roads where the speed limit was 75mph, and throughout the trip noticed that almost no one exceeded the speed limit.

One of the things that has most struck me since I've arrived at the U.S. is how long commuting takes. People drive too slow, lanes are under-utilized (why so many lanes blocked with a red X sign and so many "emergency stop" lanes?) I mean, there is clearly lots of investment in infrastructure here but something seems wrong.

Google maps says it takes 18 min to get from Fairfax to Arlington, I usually take more than that to get from my apartment (in fairfax) to GMU fairfax campus.

I Brazil I usually beat google maps ETA's, here in the U.S. its impossible.

Speed limits would seem to go against Romney's newfound disdain for gov't mandates...

It is really obvious that both the author and most of the commenters live east of the Mississippi.

What happened in the West when the 55 MPH speed limit was imposed? It was roundly ignored. And then, when the limit was raised, people kept doing what they had been doing: driving 10 MPH above the posted limits.

In California (yes, California, the home of the environmentalists of legend), nobody drives the Interstates at less than 75 MHP unless in a very old car and pulling a trailer. (Or a tourist from elsewhere in the country.) Even the big rigs (for who the speed limit has never been above 55 MPH) routinely go 70. Try driving 75 on I-5, and you are more likely to get a ticket for "impeding traffic" than for speeding.

And, according to the Highway patrol guys I know, their rule of thumb for writing tickets is . . . 83 MPH -- anything less than 80, you only get a ticket if you are also driving erratically, or weaving in and out of traffic, or something similarly unsafe. In short, the main effect of the 55 MPH speed limit was to reduce respect for the law.

I see, so people driving the post speed limit are the problem? Don't you think it's the people ignoring the posted speed limit? Nope, can't be, because apparently that's you.

There is interesting regional variation in this -- different driving cultures. I know US-3 in MA well, and what driving in MA/RI is like generally. I doubt that raising speed limits to the design speed would reduce all that many deaths, as drivers here are so generally aggressive and idiotic that you'd just see similar differentials but at a new higher average. You might also see more crashes due to cars being closer to their handling limits, given the tendency of people here to make severe swerves even through they're driving a beat up, rusted out '93 Olds with bald tires.

In contrast, I also spend a lot of time in WA/OR. For western states, they have low limits -- Oregon is still 55mph on most controlled-access roads other than interstates in the middle of nowhere. But you see widespread compliance with those limits. I was recently on business out of Seattle, and where I-5 had a 70mph limit traffic was moving at an extremely even 67-69mph, almost no one going over 75. Where the freeways in Portland/Seattle are posted 55mph, lots of people stick to those speeds -- far more than in New England -- even where designs would allow faster. Journalist Robert Kaplan once noted that he felt like he was in Canada when in the US Northwest, given the way drivers there follow rules.

This line is amazingly biased and leading:
"When the speed limit is set too low you get lots of people who safely break the law and a few law-abiders who make the roads more dangerous."

1. How do you define too low? That's a straw man argument. You are trying to instill the thought that 55 is too low.
2. The law-abiders make it dangerous? If the danger is in variable speed, then you could argue that if everyone merely obeyed the law everyone would be driving 55 and the danger would be lessened. In that case, it is the law-breakers that are making the road more dangerous.
+ You had a situation in which people were speeding and others were driving the speed limit. Accoroding to you that variable speed is what makes the roads dangerous, not the speeding. In that case I would argue that both parties are equally responsible for creating the dangerous environment. You are obviously biased towards driving fast and slant your argument to paint those driving the speed limit as the ones causing the danger. I too like to drive fast, but the way I see it, both the speeders and the law-abiders were contibuting to the problem. The only difference is that some were obeying the law, and others were breaking it.

If you want to make people obey the law, then enforce it better. On a toll road, it should be easy. You are measuring the location and time of the vehicle at specific points, and you know the distance between the points. It is easy to calculate the average speed. If that speed is over the posted limit, then assess the fee automatically, charged to the toll tag or EZPass account. Don't call it a ticket, of course. A ticket would be a fine for the driver, and you don't necessarily know who the driver is. A toll surcharge would belong to the owner of the account.

Atlanta GA to Cordele GA on I-75: Speed limit varies between 55 - 65 and 70, but let me assure you that if you're doing less than 80, you're probably getting in everybody's way and therefore more likely to get into an accident. My general rule of thumb is, maintain the speed that everybody seems to be travelling at and get home safely.

If you are trying to use the argument that the 55 mph speed limit is used to decrease fuel can you ignore that so many people drive alone in (compared to everywhere else in the world) huge cars. Most SUVs are useless. Almost everyone that I see driving on my commute to school is driving alone. The only point of getting an SUV, to use it in bad weather conditions is also broken - people are just shit scared to drive if it snows a bit. So why get an SUV? Because its "safer" due to the amount of metal? There's a lot more science to a safe car than just its mass. The only point at which mass matters is if you're a truck.

Secondly, I think cops should do more productive work, rather than issue speeding tickets. Taken a bit to the extreme, but I agree with James May when he said that, it should be illegal for the cops to give you a ticket until they've found the criminal responsible for breaking into your house.

The real danger on highways and back roads is people talking/texting while driving. If you want to test the hypothesis (and risk your life at the same time), take a spin in Greenwich, Connecticut where i have literally been run off the road at least three times. When i honked at the oncoming vehicle(s) as they drifted into my lane, i got the finger in response. I would welcome chips in phones and mobile devices that send a signal to police when used in a moving vehicle. "Big Brother"? You bet— bring him on.

I believe in Germany there are Public Service Announcements, educating drivers to "Drive Right", something you do not see in the United States, driver training on the highway is not even mandatory, if the student is uncomfortable they are not required to receive highway training. Just today, 4 or 5 cars I encountered were doing at least ten under the speed limit forcing me and several cars following me at the appropriate speed to slow down and wait for them to get over, creating a ready made situation that will results in a pile up with a single mistake.

Anyway...My car gets better mileage at 70 than 55. This best fuel mileage for a given vehicle is a function of engine size, rpm, and transmission gearing not pure speed...obviously!!!!

...and also rear end gearing in cars with rear wheel drive...

I was recently a passenger in a car that was passed by another vehicle doing at least 30mph faster. This visibly scared the driver, who proceeded to curse about speeders. My only reaction was that she wouldn't have been startled at all if she'd been checking her mirrors.

Yes, higher kinetic energy results in higher danger - but only when an accident has taken place. People who are aware of their surroundings tend not to get into accidents in the first place. This is why reducing speed variability works - it helps to reduce accident frequency. If you slam into an obstacle at 90mph then, yes, it will be worse than if you do so at 55, but that is an unrelated point.

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