The Wrong Way to Set Speed Limits [ST06]

In southern Italy they have a fantastic and economic way of slowing cars down: they just don’t maintain the streets at all and let potholes grow everywhere. So drivers are in constant fear of damaging even their SUVs. Works perfectly.

Being a European and having played American Truck Simulator, I kept getting confused by the constant speed limit change, despite literally nothing else changing with the road. It feels so incredibly arbitrary.

Civil Engineer here. The “sending your lowest paid intern out with a clipboard” part is hilarious and 100% what happens every time our traffic department needs to do a traffic study

We had a highway/traffic engineering professor at UMaine who taught this exact approach. This was back in the 90s. And, probably to the surprise of nobody, he was from Sweden.

"This approach seems reasonable, until you think about it at all." This is amazing and widely applicable.

I'm quite amazed by the design of the signs themselves. If I were the driver in Canada, I would surely miss some 90% of the speed limits. They don't pop out and are put in corners. In contrast, every country in Europe uses a prohibitory round-shaped sign with a red outline to indicate a speed limit. They, for most of the time, stick out and are placed in easily accessible places. Maybe this is another thing that the US and Canada need to look in to.

I have to admit, I had zero interest in any of these topics until I came across your channel. Now I'm buying books and looking in to how I can help affect change. This is honestly the best series and channel that I have had the pleasure of viewing. You make the subject come to life and have relevance to your viewers. Keep up the excellent work.

5:24 "most people don't consciously think about what speed they're going" Then there's me who checks my speedometer every five seconds because I'm paranoid about being pulled over for no reason

In France and other places in Europe, when you come from a country road with 80 km/h limit to a village with 50 or 30 km/h limit, they often have various kinds of bends, chicanes, dividers and poles forcing you to slow down. Very effective

The amount of common sense dismissed due to perceived sunken costs and bad habits of old school traffic design is unbelievable. Your entire channel is telling people very basic realities and solutions and yet I get a fresh perspective on something every time. Love it.

I suspect that one of the big reasons why there is no incentive to change these bad streets/roads/stroads is that many municipalities rely on the revenue collected from speeding tickets.

We had a road in my city that we thought had a short section with a speed limit set artificially low. We found that a speed limit study had been done and that the limit, by the 85th percentile rule, should be that same as the rest of the road. We asked the city raise the limit at a city council meeting and they refused. We then found that the city had been raising a significant amount of money through civil fines for speeding on that one section of road. We sued the city and won. We forced them to raise the limit to the same limit as the rest of the road.

Had no idea traffic designers would choose the speed limit based on the average speed of observed drivers on that piece of road. that is absolutely insane to me.

I am a civil engineer in the United States, and while I agree that there are MANY issues with roadway engineering, I have to disagree that engineers are stubborn and stuck in our ways. Nearly every engineer I've talked to and worked with would love more progressive infrastructure. That includes engineers who have been working for 30+ years all the way to new grads. We are tested and KNOW that making a road tighter and more uncomfortable will lower the average speed of the road. The main issue is that we, as the engineers, aren't the ones directly paying for the road. Whatever municipality the project is in is footing the bill. We can suggest all day that creating a road with 11 foot lanes, divided bike lanes, and medians will improve roadway safety, but if the owner sees that as negatively impacting the service level of the road (which it doesn't) then they are MUCH less likely to go for it. In the end, as with most other things, money dictates the decision.

In Australia, we tried a rule that you must slow down to 40km/h (24mph) if there are any emergency vehicles with flashing lights on the side of the road - for example, a police car giving someone a speeding ticket. The rule even applied on 110km/h highways (86mph). There was extreme pushback but the government trialed the rule anyway. The 1-year trial was ended early due to the sharp increase in rear-end collisions and videos of semi-trailers slamming their breaks to match the changed speed. In some cases you had one policeman writing someone a ticket and another in the same car with a speed gun out to catch those who didn't slow to 40km/h in time. It was a fucking mess.

Maybe the mismatch in speed design is intentional: the speed trap. Make your road subconsciously have drivers go fast, and place a single random sign informing them that the speed limit is much lower. Then the locale profits off of speeding ticket revenues. That's what's really going on.

Officer: Sir do you know how fast you were going? Me: Lemme tell you 'bout a little thing about the Psychology of Road Design

The best road sign I ever saw was at the edge of a small town in Missouri. It didn't say speed limit 35. It said the lights are timed for 35. I immediately slowed to 35 at the edge of town, stopped at one red light in the center of town and drove through about 10 other traffic lights all of them green.

And this is how we get infamous "speed traps". When the police in the town lower the speed limit to half the design speed of a road to meet their traffic fine quotas. There is a 4 lane road in my hometown that changes from 55mph to 30mph for no descernable reason. I and my coworkers used to avoid it completely because its so hard to focus on maintaining a crawl on a wide road and the fine wasn't worth it.

When i was growing up i had to cross a low-speed, two-lane street on my way to school. It was quite a long and straight stretch of road so people often drove way past the speed limit there. At some point the crossing was re-built so it was only wide enough for one car to pass through. At the time I thought this was stupid, as I could not understand why the change was made. I now see it as a simple and clever solution to a problem, a solution which works on multiple levels. It forces drivers to slow down and to be more aware of their surroundings, it makes the street narrower where the pedestrians cross which in turn means less road for them to cover, and it makes the pedestrians more visible to the drivers as they are no longer only in the peripheral of their vision. A very simple, cheap and effective way to make it safer for children to go to school.