San Francisco’s study to connect highway “managed lanes” from the city into San Mateo County shows an improvement in “person-throughput”  between 100 to 2200 travelers, depending on direction and time of day, an increase of 2% to 43%, with managed lanes on a combination of 101 and 280.   Rather than adding a lane, as is being contemplated in San Mateo County, San Francisco is considering converting a travel lane.

However the high level results being presented on April 10th to the SFCTA board do not show how much, if any, additional car trips would be sucked away from 101 onto 280, and therefore how much, additional  traffic might be attracted to the major transportation hub with Caltrain, Muni Metro including Central Subway soon, buses and shuttles.

The area at between 4th, 5th, King and Townsend, is currently chaotic and unsafe for people walking and bicycling, and will attract even more transit users, pedestrians, and cyclists when Central Subway opens and with more development under current zoning and Central SOMA plan.

It’s also not clear how “express lane” tolls, free to buses and carpools, and priced for solo driver using the “fast lane” if there’s space, would interact with the city’s increased interest in congestion pricing which would logically apply to anyone driving into downtown San Francisco at rush hour, or how it would relate to the SamTrans express bus routes being studied.

Another question is how much of a bottleneck would be introduced where San Mateo’s lane addition merges with San Francisco’s lane conversion.

SFCTA plans to bring reach out to community groups over the next few months, before bringing the study to the board for next steps in the late spring that would kick off a year-long Caltrans scoping study.