What’s Up With Bus Bunching?

Patrick Sullivan | June 23, 2015

Ask any regular bus rider what their biggest pet peeve is, and inevitably the first response you will likely here is bus bunching. Why am I forced to wait for a late bus only to have 2 buses on the same route arrive are the same time? Why aren’t they spaced out better? How hard can it be?

What is bus bunching? NewScientist explains:

Public transport vehicles – underground trains, for example – set off from the start of their routes equally spaced. The problem starts when one is briefly delayed, making more time for passengers to accumulate at stations further down the track. Since passenger boarding is the main factor delaying trains, these extra people slow the train even more.

Meanwhile, the gap between the delayed train and the one behind is shortened. That means fewer passengers for the train behind to pick up, making it pass through stations faster until it catches the train ahead. Eventually, all the trains on a route can end up crawling after the slowest, lead train.

Well, this cool new interactive website from Setosa and the UC Berkeley Transportation Engineering Department shows just how easy it is for buses to bunch. Minor, almost unnoticeable boarding delays or traffic can allow the vehicles to catch up to each other. Kill a few minutes (or an hour) as bus overlord to get a sense of how bunching really happens.