[eloisius]

The lengths highway patrol go to enforce speed limits manually is insane to me. I've never understood why, if speeding is such an important thing to prevent, why don't they use camera enforcement. If you travel between cameras A and B in less than the minimum time it would take at the speed limit, somewhere along the way you were speeding. There's no way around it. You could speed and then travel slower than the limit to average it out, but there would be no point, and enforcement is already spotty. Just send the ticket in the mail, or dispatch a patrol car if someone is speeding recklessly fast.

It seems like it would calm traffic, because people would travel the speed limit instead of speeding and then abruptly dropping from 90mph to 65 when they see a cop hidden behind a bridge. I've seen demonstrations that traffic waves cause jams even when there is no problem with throughput, just because someone slammed on their brakes. I'm actually not sure what it'd do to ticket revenue. If there was no way around it because your average speed gets measured, I guess people would stop speeding. Maybe the gambling aspect of it is desirable to governments because if there's a small chance of getting a ticket, lots of people will speed and thus get tickets. If tickets are a certainty, no one speeds and revenue dries up.

Do police unions lobby against using this kind of enforcement because it'd mean less cops lurking under bridges for an easy payday?

[vgeek]

Traffic enforcement is just a state/municipality funded jobs program. On the interstate they seem to solely target speeders, while ignoring the packs of cars following <1s behind each other-- which should be easy enough to spot while stationary in the median. They also seem to selectively enforce, when they should probably be taking into consideration that a 3.5 ton lifted pickup truck with mud terrain tires going 10 over and tailgating is much more dangerous than a Toyota Camry going 10 over by itself, but you never see the pickups pulled over. In most cases, they're not making the highway safer by giving someone a ticket for going 80 in a 70 when the roads are sparsely populated. If they were actually there to promote safety, limits would be set at the 85th percentile[1] and then enforcement would be on actually dangerous driving behaviors such as tailgating, aggressive lane changes and excessively different speed vs flow of traffic.

There are places in the US with "hidden" speed cameras on interstates-- I think Sioux City, IA has them. They're marked on Google Maps & locals know to slow down near the signs that hide them, then immediately speed back up. Strangely enough, traffic doesn't accordion as much such as when an unexpected braking event happens otherwise.

[1]https://www.strongtowns.org/journal/2020/7/24/understanding-...

[derbOac]

In a state I lived in, these kinds of camera-based enforcement of vehicle laws were ruled unconstitutional (state constitution). The argument was that traffic laws apply to the person driving the car, not the car, and it's too difficult to tell from videos who is driving the car. There were probably other arguments against them but basically the state supreme court decided there was no way a camera could establish evidence at the level of certainty needed.

It's odd now that I think of it because traffic cameras used for other reasons have been used in felony investigations (eg, murder). My guess is in those cases they have to establish that the person being charged was likely in the car?

I think it's the automatic charging aspect of it.

[Gare]

In Croatia, the owner of the vehicle is responsible to identify the person driving. Otherwise, he pays a fixed fine.

[eloisius]

That seems reasonable to me.

[jimktrains2]

> The lengths highway patrol go to enforce speed limits manually is insane to me.

Enforcing speed limits is not among the things that I think police try at all to do. I rarely see anyone pulled over while driving, and of those, I reason, not all are for speeding; meanwhile cars fly by me constantly at 20 or more beyond the posted limit. I live in Pennsylvania and drive through the Commonwealth and near by states with some regularity.

Although I do think more should be done to both enforce speed limits and make posted speed limits more sensible/natural.

[OJFord]

> I've never understood why, if speeding is such an important thing to prevent, why don't they use camera enforcement. If you travel between cameras A and B in less than the minimum time it would take at the speed limit, somewhere along the way you were speeding.

I don't know about the US, and I suppose it varies between states anyway, but in the UK that's exactly how it works on our motorways and some larger dual carriageways.

[charcircuit]

There are legitimate reasons why someone would go faster than the speed limit (safety) that your simple 2 camera setup would not be able to understand.

[Spare_account]

Could you elaborate on some of the safety reasons for exceeding the speed limit, to help me understand?

We use average speed cameras in the UK to enforce temporarily reduced speed limits during road repairs on the motorways. It seems to work quite well, it certainly feels like most people adhere to the reduced limits.

Personally, I am aware that if I speed (for whatever internal justification I convince myself of), I just need to reduce my average speed by the time I pass the next camera (they're big and yellow and deliberately conspicuous so drivers know where they are).

[bradstewart]

Health emergencies or something like that. Though I think it'd be pretty straightforward to say "hey I was going to the hospital, overturn this ticket please" after the fact.

[eloisius]

I’ve never had an officer understand my legitimate reason either, and even if they had, the time spent checking my ID and running insurance would far exceed whatever time I gained by speeding.