WSDOT Should Require R-8A Capacity Demonstration

The previous post opined that the Mercer Island response to the FHWA August decision not to allow MI commuters use the HOV lanes to access the I-90 Bridge typified its failure to recognize Islander commuting problems.   This post details how all I-90 Bridge commuters could face extensive delays and potential gridlock unless the WSDOT demonstrates the 4^th lanes added to the bridge outer roadway (R-8A configuration) for HOV will allow it to accommodate all cross-lake vehicles when they close the center roadway in 2017. 

One would have thought the FHWA would have required the demonstration.  They were the ones who, in a September 2004 Record of Decision (ROD), included the following description of R-8A

Alternative R-8A will provide HOV lanes on the outer roadways.  It will retain the existing reversible operations on the center roadway with both lanes

Instead Sound Transit and the WSDOT persuaded a federal judge as part of the “Freeman” litigation that their R-8A, which added the 4^th lanes to the outer roadways didn’t need the center roadway for vehicles.   It was this decision that allowed Sound Transit to proceed with plans to install East Link on the center roadway.  What’s “interesting” is the WSDOT cited the very same ROD to justify allowing center roadway closure. 

Thus, the modified outer roadway’s capacity is of some “concern”.  Particularly since extensive delays on HOV lanes between Everett and Seattle indicate a lack of capacity.  At least on I-5, allowing both non-transit and transit HOV on the same lane dramatically increases travel times.  On I-5 transit travel time could easily be shortened if the WSDOT restricted one of the two HOV lanes to buses.  (They will probably have to do that eventually because the billions spent on Central Link spine will never provide the transit capacity needed to reduce congestion.)

The risk of extensive delays on I-90 Bridge outer roadway is even higher.  While they could restrict the HOV lane to buses to avoid transit delays forcing non-transit HOV onto GP lanes would increase their congestion.  (The WSDOT 2006 and 2007 agreements with Mercer Island indicate their intent to implement HOT lanes, purportedly to reduce congestion but a sure way to gain revenue.  The increased I-90 congestion would also "likely" increase WSDOT toll revenue from 520, especially since Sound Transit 3 "declined" to include BRT on 520)  Even when East Link begins operation in 2023, its limited capacity (~ 6000 riders per hour in each direction) will force the vast majority of cross-lake commuters to use non-transit HOV and SOV’s.

Surely the concerns justify demonstrating the modified outer roadways have the needed capacity.  They could do so after completing the HOV lanes on outer roadways by temporarily closing the center roadway. (A cynic might suspect Sound Transit delayed adding the 4^th lanes until they were ready to close the center roadway to preclude doing the demonstration.)  It’s unlikely any delays in final roadway closure due to the temporary closure would significantly affect light rail construction schedule.

Unfortunately neither Sound Transit nor the WSDOT have any plans to do so.  They need to be “persuaded”.  Again, the FHWA should be queried about the differences between their version of R-8A and WSDOT/Sound Transit’s.  The Seattle Times could bring public pressure to demonstrate capacity.  The legislature’s House and Senate Transportation committees could use their WSDOT oversight to insist on a demonstration in the upcoming session if not before.  

In conclusion, I-90 commuting could change forever in 2017 if the lack of capacity results in extensive delays and frequent gridlock on the bridge outer roadways.  Future growth will only exacerbate the problem.  The WSDOT needs to be “persuaded” to demonstrate it won’t happen.