Sound Transit 3 Operating Cost “Surprise”

Previous posts have opined on the “surprises” awaiting east side commuters from Sound Transit’s East Link extension.  This post is an attempt to explain why commuters throughout the area will likely be “surprised” by Sound Transit 3.   As with the East Link “surprises” it’s the result of the media’s willingness to go along with Sound Transit‘s approach that "the less voters know about ST3, the better their chances of approval". 

For example, many commuters will be "surprised" when the Central Link extensions to Northgate and beyond begin operation that the Seattle tunnel, at least according to a 2004 PSRC study “High Capacity Transit Corridor Assessment,“ limits light rail capacity to 8880 riders per hour (rph) in each direction.  They based that capacity on their conclusion the tunnel limited light rail to one 4-car train every 4 minutes and that the 74-seat cars can reasonably accommodate 148 riders.   The 8880 rph is a fraction of what’s needed to reduce congestion on I-5 and the East Link share, 4440 rph, is about half the current peak transit capacity on I-90

Transit commuters will be further “surprised” to learn they won’t have access to even this limited capacity unless Sound Transit decides to spend hundreds of additional millions adding parking near the stations or on P&R lots with connecting bus routes to stations.

However,  another ST3 “surprise" will be the huge operating costs for the “Prop I and beyond” light rail extensions. The whole idea of light rail transit is based on the presumption that, compared to adding more bus service, increased light rail capacity and reduced operating costs will offset the costs for constructing the light rail extensions and buying the light rail trains. 

However, 75-80 high capacity buses could provide the 8880 mph capacity without spending a dime on light rail construction.  (A 70-ft articulated bus has a rated capacity of 119 sitting and standing riders.)  A light rail car costs ~ $6 million, about 5-6 times what a high capacity bus costs.   Sound Transit’s 2016 budget estimates each light rail car costs ~ $25 per mile to operate vs. ~ $10 per mile for buses.  (Both of these costs exclude depreciation, presumably far higher for light rail cars.) 

Thus a 4 car train costs ~$100 per mile to operate, and achieving the 8880 rph requires 15 trains costing $1500 per mile.  With 75 buses, the same capacity could be achieved at an operating cost of $750 per mile.  Sound Transit’s plan to use light rail cars rather than buses increases operating costs by $750 per mile.  Assuming they average that capacity over 15 hours per day and 90 hours per week means light rail operating costs will exceed bus costs by $3.5 million annually for each mile.  

Since each mile of extension adds two miles of operation for a round trip, the hundreds of millions spent installing a mile of light rail tracks rather than using buses will result in $7 million increased operating costs annually.  Sound Transit could have terminated Central Link at a UW stadium station T/C using its 8880 rph capacity for SR 520 BRT riders in both directions.  (That’s twice the capacity East Link will provide for I-90 commuters.)

Instead Sound Transit’s 28.2 mile “Prop 1 and beyond” ST3 extensions to Everett will add ~$200 million each year to operating costs over what buses would cost.  A similar analysis would presumably show the East Link and Central Link extensions to Tacoma will add another ~$200 million.  The higher light rail car depreciation costs will likely add another $50 million.

The bottom line is the billions Sound Transit 3 will spend extending light rail from Everett to Tacoma will have a miniscule effect on I-5 congestion and actually increase I-90 Bridge congestion.  The “surprise” the extensions will also increase annual operating costs by ~$450 million is truly “pouring salt on the wounds”.