Seattle has some of the highest volume bus corridors in the United States, all of them converging on downtown surface streets. The Downtown Seattle Transit Tunnel, which formerly carried only buses underneath downtown, was retrofit to include Seattle’s Central Link Light Rail in 2007. But recent upgrades to the light rail services have made this dual use less practicable. As a result, hundreds of additional buses per hour will need to be accommodated on already-congested surface streets , at the same time that Seattle is trying to accommodate an increase in cycling. Third Avenue is already bus- and local traffic-only during peak hours and even without the new buses from the tunnel, Third Avenue buses crawl at a pace slower than 5 mph. Bus lanes on parallel Fourth and Second Avenues are also nearly saturated.
The Center City Mobility Plan (also known as One Center City) is tackling these competing needs both by bus route changes and infrastructure improvements. BRTPlan has been working with SDOT and Nelson Nygaard on bringing more BRT elements into the Second, Third, and Fourth Avenue bus corridors in order to speed up bus speeds and increase the capacity of these streets to accommodate the buses that will be dislocated from the bus tunnel.