New proposals for a second tunnel would increase cost, but none provide a compelling rider experience. Let’s just improve our existing tunnel and use the savings to make up for lost time on other projects.
ST3 promised higher capacity transit through downtown by building a second tunnel with seamless transfers at Westlake and Chinatown/International District (CID), along with an additional Midtown station at 5th & Madison. But after looking into the details, the seamless transfers may not be achievable. The tunnel would be far more complex, time consuming and expensive to build than anticipated. It would also burden the CID, which has already seen a lot of construction-related disruption and loss of properties. Sound Transit abandoned the idea of a station on 5th Avenue South and proposed a shallower 4th Avenue South station. But this station would increase construction time and cost. Because of the additional burden to the neighborhood, there have been two recent guest editorials against it, in The Seattle Times and The Stranger. Sound Transit responded by proposing to combine the Midtown station with a North CID station close to Pioneer Square and/or a South CID station as an alternative. Unfortunately, neither station would provide easy access to the heart of the CID, nor to King Street station with Sounder, Amtrak, the streetcar, and many bus lines along Jackson Street, 2nd Avenue, and Yesler Way. Currently the 1 Line stops at 5 stations downtown (Stadium, CID, Pioneer Square, University Street, Westlake). This new line would now stop at only 2 or 3 stations, forcing a transfer at SODO which neither provides frequent service nor is well designed as a transit station, as Stephen Fesler pointed out. Residents are concerned it would break South Seattle apart when they are already suffering from frequent accidents and disruptions due to the at grade alignment.
While various alignments and station locations have been discussed, It is time to focus on an alternative which Sound Transit considered before they put the 2nd tunnel proposal before voters: to upgrade the existing tunnel to allow interlining of all lines through the existing tunnel. Capacity would increase, likely with better signaling systems and better ventilation. MUNI did this in 2010 and Frankfurt just started. This would avoid any disruption of the CID, be available much sooner, and be much better for riders. There are more stations in the existing tunnel, they are closer to the surface. Same direction transfers would be trivial. Reverse directions would be easy, and even easier if center platforms were added. The carbon footprint would be far lower (WSBLE is currently estimated to generate 3 million tons of carbon), and of course, this would be much cheaper.
ST3 is facing numerous cost overruns outside of downtown. These threaten to degrade and delay projects. Improving the downtown tunnel and running all the trains through it would save money, provide improvements to the neighborhood without burdening them, and be much better for riders. It is time for the Sound Transit board to study this option.