Traffic Lab Condones Lynnwood Extension Insanity

The Seattle Times March 23^rd B1 page Traffic Lab article, “Lynnwood light rail could be a budget beneficiary” is hardly the good news suggested by the article.  Even with the federal grant local tax payers will be required to pay close to $2B of the $3.1B extension that will do absolutely nothing to increase transit capacity into Seattle.  Neither Sound Transit, nor apparently the Seattle Times Traffic Lab, recognizes routing Central Link through the Downtown Seattle Transit Tunnel (DSTT) severely limits its capacity.

A 2004 PSRC Technical Workbook,  “Central Puget Sound Region High Capacity Transit Corridor Assessment” concluded the DSTT station lengths limit trains to four cars and that safe operation requires a minimum of 4 minutes between trains, or 60 light rail cars per hour.  The PSRC Technical Workbook also concluded the capacity of the 74-seat light rail cars was limited to 148 riders for a total capacity through the tunnel from Everett into Seattle of 8880 riders per hour (rph); a fraction of the transit capacity required to reduce congestion.

Sound Transit initially sold light rail as a link between UW and Tukwila with an early extension to SeaTac.  At the time they projected 70,000 of the projected 110,000 riders would come from the University Link.  A University T/C would provide an interface between 520 BRT and light rail, benefitting commuters from both sides of the lake. It included a 2^nd Montlake Cut Bridge to facilitate BRT service.  Terminating BRT routes at the UW would have allowed light rail to eliminate most if not all of the 520 bus routes into Seattle with the return routes providing Seattleites with light rail/BRT connections to Microsoft and Bellevue.   

Instead Sound Transit used purported UW objections to eliminate the T/C at the UW stadium parking lot, the 2^nd Montlake Cut Bridge, and extend light rail to Northgate.  They plan to spend $2.1B on the extension they’ve claimed would attract 15,000 daily riders, a fraction of what the UW T/C would have provided.  Especially since large numbers of commuters would use T/C BRT connections in both directions.  

Sound Transit’s 2017 4^th Quarter weekday average boardings at UW and Capitol Hill totaled 17,487 with most presumably morning commuters into Seattle to Westlake or University Stations in DSTT.  Assuming half of the 15,000 Northgate Extension riders were also commuting into those stations in Seattle (again very few will likely commute to Northgate in the morning) gives a total of nearly 25,000 every morning.  Accommodating their projected ridership into the DSTT with the Northgate Link and PSRC 8880 rph capacity will take nearly three hours.  

Surely Sound Transit’s decision to spend $3.1 B extending light rail beyond Northgate to Lynnwood is absurd.  Yet the Traffic Lab article gives credence to Sound Transit claim the extension will add 68,500 daily riders, presumably adding 34,250 commuters into Seattle every morning.  (They fail to mention the additional 37,000 riders Sound Transit claims they'll get from the billions spent on Everett extension.)

The Seattle Times describes Traffic Lab as a “project that digs into the regions thorny transportation issues”.  It doesn’t take much “digging” to recognize it will take nearly 4 hours for light rail to accommodate just the Lynnwood Link riders every morning.  Most would consider that a “thorny transportation issue” worthy of mention in article.