Seattle’s World-Class Congestion

The February 21^st Seattle Times article about Seattle metro area congestion ranking 20^th in the world and between 4^th and 10^th in the United States is no surprise to the area’s commuters.  What will be a “surprise” is the fact their recent ST3 approval giving Sound Transit the authority to spend $54 billion over the next 25 years will do little to reduce congestion along I-5 or I-90.  And that the WSDOT attempts to use HOT lanes to “manage congestion” on I-405 will only increase congestion for those using GP lanes.  .

The vast majority of ST3 funds will be used to create a light rail “spine” between Everett and Tacoma along I-5 and between Redmond and Seattle along I-90.  Unfortunately Sound Transit chose to route the spine through the Downtown Seattle Transit Tunnel (DSTT).  The Puget Sound Regional Council (PSRC) concluded in 2004 the DSTT limited light rail capacity to 8880 riders per hour in each direction.  The did so on the assumption that the DSTT station lengths limited light rail trains to 4 cars, that safe operation required 4 minutes between trains, and that each 74 seat car could accommodate an average of 148 riders. 

One can haggle over train frequency and car capacity but whatever the result, light rail through the DSTT will never have capacity needed.  The fact the Tacoma and Redmond spines have to share this limited capacity exacerbates the problem.  ST3 funding will increase I-90 bridge congestion due to light rail confiscation of center roadway and the WSDOT failure to demonstrate FHWA was wrong to claim center roadway lanes were still needed with R-8A lane added to outer roadways.

Worse, Sound Transit doesn’t commit to adding the P&R stalls and connecting bus routes to use its limited capacity, apparently assuming large numbers of commuters will chose to live within walking distance of light rail stations.  Without the added P&R stalls and connecting bus routes the light-rail-spine trains will likely be used to replace transit buses having minimal effect on I-5 and I-90 congestion.  Even with the added parking the light rail spine will fail any rational cost/benefit analysis due to cost of light rail construction and light rail car operating costs

Seattle congestion could benefit from ST3 funding with light rail extensions to Ballard and West Seattle, the “likely” reason for the 70% Seattle voter approval critical to its passage.  The relatively short route lengths will minimize construction and operating costs.  The lower costs combined with the number of commuters within walking distance of light rail stations dramatically improve any cost/benefit assessment.  Yet Sound Transit delays the two extensions that will benefit Seattle residents for 20 years. 

Most commuters along I-405 face ever increasing congestion because the WSDOT has concluded the way to “manage congestion” is to make it more difficult for carpoolers to use HOV lanes and for those unwilling or unable to carpool pay a HOT fee to use HOV lanes.  They chose to initiate HOT on the HOV lane between Lynnwood and Bothell despite the fact the PSRC had concluded the delays there were minimal. 

Between Bothell and Bellevue they used a new lane for HOT rather than GP use without ever demonstrating the ability of the added lane to reduce GP congestion.  Even worse the WSDOT plans to use added lanes between Lynnwood and Bothell, and Bellevue and Renton for HOT.  WSDOT proposals to “manage congestion” by limiting two of four roadway lanes to +3HOV and those willing to pay tolls will only increase current congestion and future growth will surely exacerbate.  They already have plans for HOT on the I-90 bridge as the way to “manage congestion” when the bridge center roadway is closed this summer.

The bottom line is the Seattle area’s ranking as a “world class city for congestion” is only going to “improve” if Sound Transit and WSDOT continue as planned.