Excessive niceness

Traffic is backed up on a main road and moving slowly. A small number of drivers want to enter the main road from a side street. The rules of the road say that drivers on the side street need to wait for a gap in the traffic, but drivers on the main road often slow or stop to let them enter. The cost is a momentary delay, the benefit is getting a smile or a wave from the driver who was let in, and perhaps a bit of good karma.

But there is an externality on all the other drivers queued up behind on the main road, as they are slightly delayed too. Thus there will be too much niceness and everyone gets delayed more than necessary. So next time you are thinking about being nice and letting someone in, don’t do it, and play your part to reduce negative externalities :)

This also made me wonder whether traffic signals use economic concepts when calculating the timing of their phases. With enough sensors in the road it should be possible to optimise (ie minimise) total delay.