Bus bunching

Why, after a long wait, do two or three buses often come along at the same time with riders crammed into the first one or two buses and the remaining buses running nearly empty? This problem is known in the transit business as “bus bunching,” and it vexes all transit agencies whose buses use common streets instead of dedicated “rapid transit” lanes.

There are many factors contributing to bunching, including:

• Traffic patterns
• Weather, accidents and construction
• Passenger variance at bus stops (crowded stops take longer to board)

Because of the unpredictable nature of bunching’s many causes, no transit agency is likely to be able to eliminate the problem—but CTA is doing a number of innovative things to manage it. Two of the most promising are traffic signal priority, which would give buses a few more seconds to get through the light (doesn’t sound like much but multiply the extra few seconds by 2000 buses and 12,000 bus stops all day long) and a GPS-based Automatic Vehicle Location bus tracking system to let our control center monitor the spacing of buses in real-time. As you can imagine, the data-crunching necessary to do this is pretty significant, but we’ve got some promising pilot projects in place.

We’ve also added express routes and high capacity buses to meet increased ridership demands. CTA planning staff continuously monitor bus routes to ensure that buses move as quickly as possible through an area while staying accessible to riders. And they work with Bus Operations staff to ensure we have the appropriate buses deployed on the street. CTA also remains in close contact with the City and other municipal agencies that supervise streets, construction projects and other potential “road blocks.”

There are two things customers can do to help speed things up – exit from the rear doors, and get a Chicago Card. The longer a bus sits at a bus stop, the slower your trip.

While we’re at it, a number of folks have asked why some buses stop every block to pick up passengers. CTA tries to space stops every other block where we can, but we work with local elected officials (Aldermen, village managers) to do this. In some cases, senior centers and other high-traffic locations make spacing every other block difficult to do, but please let us – and them – know about bus routes that you think should be sped up with more widely spaced bus stops.