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Comment by advisedwang | Hacker News Reader

The UK has "average-speed cameras", which use number plate recognition to see when you enter/exit a long stretch of road, and from that measure your average speed over a significant period. You can't just slow down for the camera. They are extremely effective - in practice traffic does slow down to the posted speed limit. Unpopular as they are, I wonder if they should be deployed widely.

(These are usually deployed near roadworks)

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I agree. I can’t say that I love speed cameras, but these do genuinely have a big impact. The other thing they tend to do is even out the traffic - everyone is travelling at a speed close to the vehicles around them. (It’s rare for vehicles to drive a lot slower than the camera-enforced speed - whereas there is a lot of speed variation between vehicles on motorway stretches without cameras.)

So in addition to the reduction in speed, you’ve got smaller speed differences between vehicles and also a much more even and steady traffic flow which can help prevent that traffic jam inducing stop/start behaviour.

I reluctantly think they should be used more widely. (And I say that as a U.K. driver who is not unfamiliar with receiving the odd speeding ticket in the past).

This is such an obvious extension of the concept, but I've never figured out why they aren't used in the jurisdictions I'm familiar with. Privacy related to license plates? Numerical calculations not being valid grounds for incrimination?

I sense constituents would be livid and would vote accordingly. I suspect the same backlash around red light cameras and mobile speeding vans would arise and the program would be cancelled after about a decade or so.

It really depends on the municipality: I would vote for this in a heartbeat, and so would a lot of other people in my area. There would also probably be some opposition, but I don't think it would be particularly lopsided against these kinds of cameras.

Do you drive?

Nope. Under 40% of households in my area own cars; in the area I grew up in, it's under 25%[1].

[1]: https://edc.nyc/article/new-yorkers-and-their-cars

I think it is one of those things people might broadly support, until they themselves get a speeding ticket and start throwing a fuss. Traffic laws, in particular, are things people want strongly enforced on everyone else.

That's absolutely true, although it doesn't change the equation much for my area: most households here don't own cars.

The problem with speed cameras around here would be that they dropped all the speed limits and now everyone routinely does 15+ mph over the limit.

It's insane - the laws are obviously made to be broken because nobody wants 100% enforcement.

There were weird court cases involving cops manually doing this in the US ages ago. Something to do with "hearsay evidence" if I recall correctly.

Something similar with "speed patrolled by aircraft" warnings.

The Mean Value Theorem is just a Theory NOT a Law!

In some places (like California), it's illegal to use a calculated average speed to issue tickets, regardless of whether it's done by a person or with cameras.

https://leginfo.legislature.ca.gov/faces/codes_displayText.x....

That's good because I'm sure they could catch tons of people speeding in the fast lane from their fastrak transponders showing up at consecutive readers too fast.

I live in SF. I feel like speeding is not really a problem in the city proper as the roads are narrow and etc. The "natural" speed limit is the same or lower than the legal speed limit. On the highways I go 80-something mph, which is legally speeding but is the typical "flow of traffic" in the left lane.

I believe it's simply because people like to speed, so they will vote against speed enforcement they don't think they can avoid.

Mostly privacy.

License plates could be stored to track you

https://www.youtube.com/watch?v=bglWCuCMSWc&ab_channel=NotJu...

This feels like doubling down on something that's not super effective.

The way to make traffic slower, is to make road lanes narrower. You can also add curves/trees or overhangs to add shadows to the road, which breaks up the roadway and makes it harder to reason about from a distance.

I don’t understand why adding things that usually make people crash is more beneficial than letting traffic normalize at a speed that may be above the legal limit.

Around me people speed, but you know what’s more dangerous? People who go 55 on the left lane. And trucks that don’t move to the right lane. They are not breaking the law in regards of speed, but everyone that’s going at the normalized pace has to avoid an obstacle.

I say leave the speed limit at 75, put everyone through a more difficult test, enforce lane hierarchy and enforce tickets above 90-95. This equals on a traffic speed of 80-85 that’s safer than adding trees and making narrow lanes

Edit: after posting this comment I come to realize what living in the US has done to me. I immediately assumed that a road with a speed trap is a highway. Which is all I see every time I get on the car anyway. The American dream.

lol, yeah, I definitely don't mean highways :)

Highways probably shouldn't have speed limits. Honestly, close to nothing should have a speed limit. How fast you can go on a highway should be entirely decided by how good your visibility is. So adding things on the sides of the road could help lower visibility by decreasing the amount of sunlight on roads.

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