[haubey]

Thanks for the clarification. But it doesn't seem unreasonable to figure out if you're speeding between two toll booths. They know how long the road is, they can tell how fast you're going. I've often wondered why police don't do more of this. It seems like a relatively easy way of catching a lot of people.

[privong]

> I've often wondered why police don't do more of this.

Wikipedia claims[0] that this is not allows in California, though the citation has suffered link-rot.

I think enforcing speeding limits could also discourage the use of things such as ez-pass, which may very well result in more revenue, compared to the same tolls collected in cash by real people. So it could hurt the revenue stream from tolls.

[0] https://en.wikipedia.org/wiki/Speed_limit_enforcement#Averag...

[kijin]

Average speed cameras are used in a number of countries, though I'm not sure about the U.S.

They are useful for catching speeders in a relatively short stretch of highway, but useless for medium-to-long stretches. Even if you constantly drive at 20km/h over the limit, the average can easily dip below the limit if you stop at a service station for a few minutes or if there's heavy traffic at some point. And if the highway in question doesn't have toll booths, the police will have to install a bunch of expensive cameras at every single interchange.

[jrockway]

They probably don't actually want to know what the 85%-ile speed is on their roads, because people could start appealing speeding tickets, and people in crashes could start suing the state claiming the roads are intrinsically unsafe.

Just a guess. But have you ever seen a local government turn down money in order to preserve civil liberties? Pretty rare these days. So there must be some sort of ulterior motive.

[eli]

Mostly it would lead to fewer people using Ez Pass and more traffic at tollbooths. Anyway, they've promised they won't do that, so that really would be a story.

[travem]

This is fairly common in the UK where average speed checks can be found on motorways. The camera systems I have seen were the SPECS speed camera [1].

[1] http://en.wikipedia.org/wiki/SPECS_%28speed_camera%29