About one year ago, Metro selected Columbia Street, using a two-way alignment, as the pathway that southbound Highway 99 buses would use between the new Alaskan Way interchange and Third Avenue after completion of the Highway 99 project. Last week, Metro released a brief summary of a traffic study intended to help the agency and SDOT determine the best way to configure the new two-way Columbia.
Metro seriously considered three possibilities. Option 1 is a three-lane configuration with one transit-only lane in each direction and one general-purpose (GP) lane westbound, which would allow room for wider sidewalks along Columbia Street. Options 2 and 2B both use four-lane configurations with one transit-only lane in each direction and two GP lanes westbound, and sidewalks of the same width as today’s. Options 2 and 2B would also allow for dedicated GP turn lanes in certain spots, while Option 1 would not. The only difference between Options 2 and 2B is that Option 2 would allow general traffic to use the eastbound transit-only lane between First and Second, which would provide GP access to two parking lots without turning across the transit-only lane.
Metro determined that Option 1, with three lanes, would have an unacceptable impact on general traffic, largely because of the lack of space for dedicated turn lanes. Given the volume of traffic turning left from Columbia onto Second, this conclusion makes sense.
Metro also determined that Option 2, allowing general traffic between First and Second eastbound, would serve general traffic better than Option 2B. Conspicuously absent from the summary, though, is any discussion of whether buses would be delayed by cars waiting to turn right from the transit lane onto Second. Given the high volume of pedestrian traffic in the area during peak hours, and the need for turning car traffic to wait for pedestrians, an impact on eastbound bus traffic seems quite likely. I would have liked to see more specific discussion of Option 2’s potential effect on bus travel times, compared with Option 2B.
One other interesting note: the study assumed 40 buses per hour in each direction during peak hours, which is a bit odd, as today there are 47 outbound buses in this corridor during the busiest hour (4:30-5:30 p.m.), with demand for more. Consistently with the brief nature of the summary, there was no explanation for the difference.