[a_m0d]

What's the problem with the marked cars driving the speed limit? If all the cars drive at the speed limit, that's good, right?

I always thought the speed limit was there as a speed limit. I've found that in Australia, speed limits are obeyed much more than in North America, where they seem to be suggestions or lower bounds on speed. Many times in Canada I've been travelling in traffic that's doing 30 - 40 kph over the speed limit. That's enough to get your car confiscated in Western Australia!

[pitt1980]

first thing that pops up when googling cost of traffic jams

http://www.cbc.ca/news/canada/toronto/story/2009/11/10/oecd-...

the cost is real, and should be accounted for

[talmand]

I would have to see a study that shows that the speed limit is the source of traffic congestion. I seriously doubt it is. Most sources of congestion seem to be more along the lines of disabled vehicles, accidents, several roads converging in the same area, merging issues, and just stupid drivers at any speed. Increasing the speed limit by 10 or 15 MPH doesn't address any of that and in fact would likely make it worse in some of those examples.

[pitt1980]

I don't have a study to link to

but I'm seen how one slow driving cop can cause a bottle neck behind him as noone wants to pass him

some links about about how seemingly minor factors can cause traffic jams

http://auto.howstuffworks.com/car-driving-safety/accidents-h...

http://www.amazon.com/Traffic-Drive-What-Says-About/dp/03072...

[talmand]

The cop car obeying the speed limit and every one behind it doing the same is not an example of congestion. As long as the cars are flowing at the posted speed limit then I don't see that as congestion, the traffic is just not speeding along as quickly as one wishes it would.

By that logic, any street that has two or more cars following the speed limit in close proximity to each other could be classified as congestion.

Once you have a buildup of cars that are traveling slower than the intended speed of the road that causes further slowing up the line that eventually creates bumper-to-bumper traffic with little movement, then you have congestion.