[dazc]

Not sure what the point of this is other than a suggestion that 20 mph zones are increasing journey times significantly?

The author acknowledges that 20 mph limits are rarely enforced and mostly ignored; and also concedes that congestion has remained the same despite efforts to reduce it.

[transportguy]

All of the things you mentioned are the points!

[dazc]

20 mph zones are increasing journey times significantly for what reason then?

[transportguy]

Most drivers ignore them, but it only takes 1 driver going at the 20mph limit in a bottleneck to slow down a whole column of traffic. So both are true.

[dazc]

OK, I'm not sure it's going to make that much difference since 20 mph zones tend to be in residential zones, typically rat runs. This indicates to me that high volumes of traffic are more likely the cause of congestion rather than some annoying people who insist on obeying the law.

Let's, for the sake of argument, say I am one of these annoying people. I will drive at 20 mph with a tail of 6 angry drivers behind me until I reach a junction or a set of lights that invariably already have cars waiting to move forward.

All I am doing is delaying the drivers behind me from reaching this queue of cars a few seconds later than they would otherwise.

Of course, their rage is directed in my direction but that's another story.

[transportguy]

You're missing the point. The 20mph rules in London have been applied to all arterial and collector roads, not just residential roads.