[tgsovlerkhgsel]

Presumably because it matches the behavior of human drivers.

If self-driving cars were widely rolled out already, any large manufacturer could probably completely break traffic nationwide by rolling out an update that makes the cars actually follow every law and speed limit. (Just like work-to-rule can be as effective as a strike.)

[Osiris]

Which, to me, just means the laws are wrong. The police often don't obey basic traffic laws like speed limits and signaling (in my experience of following police on the freeway).

[b3morales]

I recently read an interview with a highway patrol officer whose opinion was that it's not really feasible for them to drive at the speed limit. Since a marked police car is already effectively a pace car -- no one wants to pass it for fear of being pulled over -- they would just distort the natural flow of traffic and probably create tailbacks everywhere they went, which would end up being more dangerous.

I'm not sure I agree completely with this reasoning, but it was an interesting perspective.

[Osiris]

That's the same as saying that the speed limit (on freeways) is wrong because if everyone obeyed the speed limit, it would cause significant traffic congestion. In fact, you can see this when there IS a police officer driving the speed limit on the freeway and no one passes them. Traffic backs up for miles.

[waste_monk]

I recall seeing a forums post by a traffic engineer once and they said part of the process of deciding speed limits is, once the actual optimal speed for the road segment has been determined, subtract ~10mph to pre-emptively avoid complaints by the elderly that the speed limit is too high.

That was regarding suburban road planning though, not sure if the same applies to freeways and other major arteries.

[throwawaylinux]

It's not the same. The police officer is a moving speed limit restriction so cars driving at the normal speed will catch up to it and slow down and they will continue banking up for as long as the car is driving slower than normal.

You wouldn't get that banking up with everybody following the limit.

[robryan]

It becomes harder to change though because if the culture is to go x over the speed limit, people will probably still go x over the new higher speed limit.

[b3morales]

Exactly, yeah, this is the problem I have -- it's pragmatic in a certain way, but also contributing to a vicious spiral.