Q. Wouldn’t everyone drive faster if the speed limit was raised? A. No, the majority of drivers will not go faster than what they feel is comfortable and safe regardless of the speed limit. For example, an 18-month study following an increase in the speed limit along the New York Thruway from 55 to 65 mph, determined that the average speed of traffic, 68 mph, remained the same. Even a national study conducted by Federal Highway Administration also concluded that raising or lowering the speed limit had practically no effect on actual travel speeds

https://www.motorists.org/wp-content/uploads/2015/05/speed-l...

My anecdata does not support this. When roads are not congested, I can see that most drivers accelerate from ~70+mph to ~80+mph right ofter the speed limit sign changes from 60 to 70.

That's separate from how fast they think is safe on the freeway in general from a physical standpoint. If there were no limits posted, they'd go even faster.

So basically I'm saying that both you and the parent poster are both correct. It's just that more than just physical safety is being taken into account.

All this proves is that they don't want to go much more than 10 over the limit, AND the speed at which they feel safe is at least (but maybe higher than!) 80mph.

If you've ever gone much faster than is customary for a road (say 110mph following a cop), and then slowed down to say 90mph, it will feel quite slow. If you then don't set about consciously lowering your speed, you will even find yourself creeping back up.

Humans are notoriously bad at perceiving what-if dangers and being aware of our own limitations. The level of difficulty we perceive is what's required to keep up with the expected - road curves, passing other predicable cars, etc - not because we're anticipating surprises.

Another example is outdriving one's headlights - either the sheer amount of deer that get hit, or when you flip on your high beams in a fog and actually become aware of how little you could see.

Driving through rural areas you must have experienced the sudden ~30mph sign, signifying a town coming up. Did this "drive what you feel" approach line up there too? When the town was at the bottom of a hill?

For context, I've done around 25k miles cross-country non-interstate. I've concluded that what the individual states choose to sign as the general maximums has more to do with local culture and politics than with general terrain.

With respect to the engineering safety of the sudden 30mph sign (which I assume is in a rural area on an otherwise small highway); yes that sounds like you're describing what is typically called a "speed trap". A real traffic safety engineering standard SHOULD call for a clearly posted and graduated reduction in speed as approaching the town at a /bare/ minimum. However, a true engineering solution would isolate the town and the highway entirely. The point of the highway is to be a high speed transit corridor and it is inefficient and unsafe to route such a thing through a dense residential or commercial area. Instead there should be an exit system that leads off to a side path for such a town. I would prefer an actual barrier that encloses the typical route and possibly caps or bridges over it (maybe with a park) for existing situations that have developed in days with less good planning. In any such cases a designated detour route should also be constructed such that it is possible for "oversized loads", emergency response teams, and post disaster travel to route around failure in the now enclosed sections.

There are plenty of towns large enough for highway bypasses and traffic lights. The ones I'm talking about have one good road, maybe two if they're lucky enough to be the intersection. I indeed appreciate when there are graduated signs so I don't have to use the brakes, but this obviously costs money they don't all have, and isn't needed by people who already know the road. Talking about traffic engineering is laughable for such places - if your goal is to pass through as quick as possible, you could just take the interstate.

If there was not revenue generation, if the fines were required to go only in to the state or federal general budget, I believe the situation would shift towards one of the safe engineering solutions I outlined above instead of the revenue generating status quo you see today.

However, people have vastly different "feelings" for what is comfortable. I've been in multiple different driving experiences in an awd subaru where I was going 30 under the speed limit because the weather was terrible and people were flying past me in their 2wd cars.

Shit, I even had an experience where I and literally 75% of other cars full on stopped on the side of a highway with our hazard lights on because we couldn't see more than 200 feet in front of us and people were still driving 30 mph past us. I shit you not that was one of the scariest moments of my life because as the visibility got worse and worse, everyone starting putting on their hazard lights and going like 30, most cars turned off but we thought it was OK until the rain and fog got so bad the cars in front and behind us completely disappeared in the grey rain/fog. We drove for about a minute going like 25 MPH (I was slowing down to get more comfortable because I was freaking out) and I risked turning off onto the shoulder preying I didn't randomly ram one of the cars pulled off and we got lucky and were able to sit their until it got better.

Well, there's a surprising turn of events on HN: an appeal to discard the findings of a study in favor of one poster's suppositions, and another's anecdata. :-)

This is one of the reasons experts argue that you NEED to set the speed limit at the natural speed people will drive at; otherwise, you will have a big speed difference between the majority who drive at the comfortable, faster, speed, and the 15% who are driving slower at the speed limit. You want the two groups to drive at the same speed.

There is no guarantee that a speed limit will have any effect on driving behaviors. The fact is, when driving, most motorists choose a speed in which they personally feel both comfortable and safe.

on a free-flowing section in 1992, the recorded average speed was 132 km/h (82 mph) with 51% of drivers exceeding the recommended speed.

The autobahn has a long history proving that people feel comfortable and safe at excessive velocities.

So it seems that 130 km/h (81 mph) is not all that excessive.

While it may seem counter-intuitive, the Autobahn is safer than many motorways which have speed limits.

Whereas US interstates - with speed limits of 70 mph - have an average of 4.5 fatalities per billion kilometres travelled, the Autobahn only has a fatality rate of 2.7 per billion kilometres.

But 80 miles per hour is not an abnormal speed on the highway.

The posted speed limit is so rarely enforced, that it still isn’t a deterrent. For instance, the speed limit on GA 400 is 70. But you’d better be in the slow lane if you only go 70mph.

https://www.11alive.com/article/news/local/commuters-respond...

Do people driving on derestricted sections self-select and have cars better able to handle the speeds? Does anyone in Germany only drive on restricted sections?

You comment as if the derestricted sections are just some racetrack in the middle of nowhere for which people self-select. No, they're just roads going from one place to another, like any other road. And Germany doesn't kick out citizens who don't want to drive fast, or offer easy citizenship for those who do.

Luckily there are plenty of places that have done just that that we can learn from. WI just raised a lot of its highway speed limits to 70mph for example.

Anecdotally, people used to drive in the 75mph range before the speed limit was raised and would deal with the occasional ticket for 10 over. In the general case, the average highway speed seems to have stayed at 75mph after the change.

I've noticed something similar in South Dakota where the speed limit is 80. I rarely saw someone go more than 5 over, and would frequently encounter people driving at 75mph.

My personal anecdotal evidence on this, having recently driven cross country on I-80 (mostly 80MPH speed limits) and through Montana on I-90 (Again, mostly 80 MPH) shows that people drive at a speed that is safe for them. My car, and those that also seemed to drive a few MPH over the limit were all newer, highly capable vehicles, and the largest added risk was the chance of running into excessively slow moving traffic. When the visibility dropped, I slowed down, and when the visibility was clear, there was no additional risk in pushing it up a few MPH.

This is easily tested in the western U. S., where there exist states with speed limits of 75mph or higher. There's a point at which I quit getting passed, and start being the one doing most of the passing. That point is just a bit north of 80mph. Anecdotally, same point it was when speed limits were lower. IOW, when I'd ride the interstates of AZ or WY twenty years ago, my ratio of passed/passing at 90mph was about the same as it is now.

But surely someone has done an actual study on this.

Drivers mostly go the speed they are comfortable with, which is a function of the roadway’s design and conditions. Traffic engineers are learning that you can’t just slap a 30mph limit sign on something that feels like an interstate highway, but must instead use the road’s physical characteristics to slow drivers down.

I've pushed a rental Merc past 180 km/h (110 mph) on a reasonably well-paved outback road, and it was downright unpleasant to drive at that speed from the vibration. On a smoother highway I would guess it'd still become unpleasant past 200 km/h (125 mph).

Personally, I also found driving at those speeds too mentally taxing. The lack of time to react, the lack of maneuverability, and the huge braking distance were just too stressful. You couldn't let your thoughts, let alone your eyes, off the road for even a second.

On that particular trip, I had driven for 18 hours (excluding short breaks and a 3-hour nap), most of it at ~100 km/h. If I had the option of driving 180 km/h the whole time and save 8 hours, I would not take it.

That said, if there were no speed limits, I'd probably drive 130-150 km/h (80-95 mph), depending on the road, which isn't far from what volkk said.

Car chassis are very performant nowadays.

Not my car, I often look down and see that I'm going 90 when it feels like I'm going 70.

I've driven in parts of the country where the speed limit is 75 or even 80 and that wasn't my experience. There were not a lot of people blowing past me doing 95.

Then again, MA speed limits tend to be lower than surrounding states.

Also, it goes against traffic design principles, even in the US. (see: 85th percentile)