By Charles Wilson

When GRTC introduced the Pulse Bus Rapid Transit line to the public, many fretted the loss of road space for cars spelled doom for the corridor. While some people might maintain pessimistic viewpoints out of sheer habit, many might not know the reality of the positive externalities that segregated bus lanes often have on overall traffic flow.

In the midst of a similar-in-scale BRT rollout in suburban Montgomery County, Greater Greater Washington posted an article dispelling the myth that one fewer lane for cars will cause traffic to exponentially worsen. Among many other studies, they cited one from Europe that goes pretty deep into the wormhole of transportation behaviors. It articulately demonstrates that aggregate human response to traffic condition changes is far more complex and far more adaptive than any of us might be able to totally comprehend.

Figure 3 from “Disappearing Traffic? The Story So Far” shows behavioral responses to changes in road conditions.

Based off of 63 individual case studies, they found that there was a mean of 21.9% and a median of 10.8% reduction in overall traffic after these condition changes had been implemented. They conclude that:

When pedestrianization schemes or wider pavements or cycle lanes or bus (and other priority vehicle) lanes or road closures are introduced, pre-scheme predictions of what will happen are usually excessively pessimistic. In practice….[t]raffic levels can reduce by significant amounts, with the average being that perhaps 11% of the traffic on the treated road or area cannot be found in the area afterwards.

So, fear not. Buses are not the parasites in the transportation ecosystem, but symbiotic additions that deserve their own territory. This makes everyone happy.

Figure 1 from “Disappearing Traffic? The Story So Far” shows case-by-case reduction in traffic.

Photo by: torbakhopper