Throughout Metro’s network, there are a number of common-stop corridors along which multiple routes will run, usually combining for frequent service. Some of these corridors are scheduled to optimize the distribution of service frequency and eliminate bus bunching, others not so much. Along the corridors with no schedule coordination, you’re likely to see several buses come at once within the span of a few minutes, then no buses at all for the next several minutes.
A lot of this is the result of other scheduling “hotspots” in the network, or timepoints and pulses, mostly at park-and-rides, transit centers, and other major hubs were infrequent and frequent services come together at one destination. Scheduling to incorporate both timed connections at these hubs and frequency coordination along common corridors is no simple task– that’s why Metro splits up its scheduling responsibilities by each bus base.
Unfortunately, this brings up another challenge: common corridors are sometimes made up of routes based out of different bases, hence different schedulers. At Eastgate, for example, routes like the 212 and 218 combine for frequent service to downtown Seattle in the peak*. However, because both of these routes each come out of two different bases, uncoordinated scheduling often leads to bunching at the freeway stop, limiting the usefulness of passenger capacity the bus at the rear end of a bunch brings.
While an easy administrative solution is to simply apportion the routes along common corridors to one scheduler, I recognize that the network is much more complex, routes need to move around, and common corridors tend to straddle the edges of geographic boundaries. That said, Metro should develop a standard for developing coordination among separate schedulers for common corridors.
I’m not aware of any other corridors in Metro’s network where this is an issue with all-day frequent service, but assuming the free interchange of routes between bases can happen at any service change in the future, it’ll be a good practice to ensure stable and reliable service along our most heavily-traveled corridors.
*I chose this selfishly to illustrate my personal commute, at the same time recognizing that it’s not a very good example, given the limited peak-only span. If anyone has a clearer or better example, particularly with all-day service, I’d like to hear it!