Mercer Island’s Self-Inflicted I-90 Commute Problem,

The problems identified in the June 1^st Seattle Times headline, “Mercer Island braces for new I-90 bottlenecks” are at least partially the result of the Mercer City Council failure to recognize the reality of the Sound Transit East Link light rail extension.  Their East Link website video has described its operation as “one three or four car train every eight to ten minutes”.   At best, East Link will provide thirty 74-seat light rail cars an hour that, per PSRC recommended capacity of 148 riders per car, can accommodate 4440 riders per hour.   A fraction of the capacity needed to meet current and future cross-lake transit demand to compensate for the loss of center roadway. 

The more immediate Mercer Island “problem” is their loss of single occupancy vehicle (SOV) access to I-90 HOV lanes.   They should have realized that WSDOT/Sound Transit promises of exclusive SOV access to I-90 HOV would need FHWA concurrence.  Yet none of the parties involved bothered to contact the FHWA until last March.   The FHWA August rejection should have been no surprise, at least partially because of the difficulty in implementing exclusive SOV access to I-90 HOV lanes.

The last minute Mercer Island lawsuit referred to in the paper made no attempt to provide Islanders access to an I-90 HOV lane; instead requesting the judge enjoin Sound Transit from implementing 4^th lanes as HOV only.  (Apparently they, unlike the Seattle Times 31^st editorial support for exclusive HOV access, recognized the implementation problem.)  

While doing so would reduce SOV travel times for Islanders and all I-90 corridor commuters, it would increase them for buses and HOV traffic.  Thus, it’s unlikely to change current plans for HOV lane implementation.   It’s also likely the other lawsuit objective to delay closure of the I-90 center roadway for 6 months to consider the issue will fail.   Again the problem is there is little that can be done in 6 months to change the FHWA dictate not to allow SOV access.

Thus Mercer Island commuters as well as all I-90 corridor commuters will face increased cross-lake congestion.   The WSDOT allowed Sound Transit to close the center roadway without demonstrating outer roadway had needed capacity.  They chose to ignore a 2004 FHWA ROD study concluding center roadway lanes were still needed for vehicles with added outer roadway HOV lane.  The resulting congestion is likely the reason WSDOT, as early as 2007, was already planning to implement HOT lanes on I-90 Bridge.  Thus, future cross lake commuters can look forward to trying to find 2 riders or paying the very high tolls required to “maintain 45 mph” to avoid the inevitable GP lane gridlock. 

What is so absurd is the fact that, after enduring the 6 years of congestion during light rail construction, East Link operation will increase not decrease I-90 Bridge congestion.  The problem is East Link’s 4440 rph limited capacity hardly qualifies as High Capacity Transit (HCT).  Yet Sound Transit intends to use it to replace cross-lake bus routes. Presumably riders from about 50 bus routes could be forced to transfer to and from East Link at either South Bellevue or Mercer Island light rail stations.  

Not only will removing 50 buses an hour from I-90 Bridge have minimal effect on outer roadway HOV congestion, far more commuters will likely chose to “drive” rather than “ride” to avoid the hassle of transferring; adding to GP lane congestion.  Meanwhile East Link trains will likely be full before they ever reach the stations.  Mercer Island residents, being the last with access, will have an especially difficult East Link access problem

The Mercer Island HOV access problem is just the beginning of the end of their easy access to Seattle.   Sound Transit closure of the South Bellevue P&R has probably already resulted in their P&R being full with “off-islanders” before many arrive.  Former Islander cross-lake transit commuters will be forced to choose between high HOT tolls or GP lane gridlock; and East Link operation will only exacerbate their problems.

While HOV access was never likely, a Mercer Island lawsuit could have dramatically reduced the impact of the loss. They could have asked the judge to require Sound Transit satisfy the Revised Code of Washington (RCW) regarding HCT planning prior to closing bridge center roadway.  RCW 81.104.100 requires they consider, “a do-nothing option and a low capital option that maximizes the current system”.   It’s doubtful any judge would agree Sound Transit was justified in not complying with the RCW claiming they weren’t required to do so.

Its also doubtful any Sound Transit attempts to comply with the RCW will succeed since any rational analysis of cross-lake BRT would conclude it had far more capacity at far less cost than light rail: effectively ending East Link.  There would have been no need to close South Bellevue P&R or I-90 Bridge center roadway.

In conclusion the recent Mercer Island access problems are only the beginning of Islander commuting problems more effective legal action could have prevented.  Typical of the Times, rather than alerting the area about future Sound Transit problems, the article is likely way to late to change things.  The entire east side will pay as a result with East Link.  The entire area will pay as a result with the Sound Transit "Prop 1 and Beyond" spine.