Make ST Demonstrate Modified I-90 Bridge Outer Roadway Capacity

(I sent the following to the Bellevue Reporter in response to a recent article.  I posted it and intend to send emails to others suggesting they read it.  My current planned addressees include the Sound Transit Board, Seattle Times, House and Senate Transportation Committee Members, Fox, Komo, Kiro, and King TV.  Hopefully someone will pay attention.)

Make ST Demonstrate Modified I-90 Bridge Outer Roadway Capacity

The November 13^th Bellevue Reporter included an article about Sound Transit’s second of four weekend partial closures of the I-90 bridge to implement changes required for adding 4^th lanes to the bridge outer roadways.  They currently don’t intend to finish the modifications and allow commuters to use the added lanes until 2017. 

ST should be “persuaded” to expedite completing the lane modifications for two reasons. The first is the 4^th lanes will reduce congestion for commuters from both sides of the lake, especially “reverse” commuters.  Any delay adds to the years of increased congestion they’ve already endured without it. 

The second benefit is far more important to cross-lake commuters.   Implementing the 4th lane would “allow” ST to temporarily close the center roadway and demonstrate the modified outer roadways can accommodate all the cross lake vehicles.  ST asserted the added lanes could do so in the 2008 DEIS:  “Travel times across I-90 for vehicles and trucks would also improve or remain similar with East Link”.   They also convinced a federal judge in the “Freeman case” the modified outer roadway could accommodate all cross-lake vehicles; allowing them to close bridge center roadway for light rail. 

However other data dispute this contention;  The problem being allowing non-transit vehicles on HOV lanes reduces the number of transit buses, diminishing transit capacity.  One example is the Sept 2004 FHA Record of Decision for I-90 Two-Way Transit and HOV Operations Project” approving the R-8A configuration.   The R-8A, approved in that ROD, added the outer roadway lane, however it also required the I-90 Bridge “maintain the existing reversible operations on the center roadway”; presumably reflecting concern that the added outer roadway lane could not accommodate all the non-transit and transit vehicles. 

Another reason for concern is a chart in a May 8^th PSRC “Stuck in Traffic: 2015” presentation to the Eastside Transportation Project.  It showed I-5 HOV travel time between Everett and Seattle had increased to 75 minutes during peak morning commute and 68 minutes in the afternoon.  I-5 HOV travel times between Federal Way and Seattle had also increased dramatically.  Both presumably due to non-transit HOV traffic degrading HOV lane capacity.  

In conclusion, ST surely has an obligation to demonstrate closure of the center roadway won’t cause similar problems on the modified I-90 Bridge outer roadways.  Expediting the 4^th lanes and temporary closures of the center roadway will allow them to do so.  Their current plan to delay the lanes until it’s too late to prevent center roadway closure poses an unacceptable risk for commuters.