The DSTT Station Debacle

Countless posts on this blog have referenced an August 2004 Puget Sound Regional Council Technical Workbook, “Central Puget Sound Region, High Capacity Transit Corridor Assessment”.   It concluded routing light rail through the Downtown Seattle Transit Tunnel (DSTT) limited capacity to 8880 riders per hour in each direction.  They based that capacity on the conclusion DSTT station lengths limited light rail trains to 4 cars, that safe operation required a minimum of 4 minutes between trains, and that each 74-seat car could accommodate 148 riders.  

Unfortunately that document is no longer available on the Internet and Sound Transit has decreed the DSTT can accommodate 16,000 riders per hour (rph) in each direction.   Even with the 16,000 rph capacity, it will take 7 hours to accommodate the up to 112,000 riders Sound Transit claimed the ST3 extensions beyond Northgate to Everett will add; ending access for current riders and those anticipated from Northgate extension for much of the day. 

The extension beyond Angel Lake to Tacoma will presumably be limited to half the DSTT capacity.  If so, it will take nearly 11 hours to accommodate Sound Transit claims for up to 95,000 riders from those extensions, again ending access for current commuters.  Even Sound Transits earlier promises for 50,000 riders for East Link will take more than 6 hours.

Clearly Sound Transit’s promises for ST3 ridership exceed any rational capacity for light rail routed through the DSTT.  Even more “problematic” is their apparent assumption the two light rail stations in the tunnel can accommodate the return trips.  Presumably half of the up to 257,000 additional daily rides will be return trips.  Thus,  ~125,000 additional commuters will have to do so at one of the two DSTT light rail stations.

Two years ago I spent several days riding New York City subways. Subway lines there typically provide commuters with multiple stations for access.  Most stations are sized to provide commuters with access to more than 10 train cars.  Commuters pay fares to get access to the station not to ride, facilitating rapid access. Subways there provide New Yorkers with fast, reliable, high capacity transit.

The DSTT station limits on the number of light rail cars also limits the number of commuters the station can accommodate.  The idea the two stations in the DSTT can accommodate up to 125,000 additional riders during an afternoon commute goes beyond “problematic” to absurd.  The need to pay fares on the train will likely increase station times reducing train frequency, adding to the absurdity. 

Thus, the DSTT not only limits light rail capacity to a fraction of what’s required to meet Sound Transit ridership claims, the stations will never be able to accommodate the capacity it does have. It’s way past time they acknowledge both realities.