"Sound Transit's low capacity passenger railroad scheme should be a wake up call to the region's freight community. State Government owns the I-90 bridge and should be persuaded to prevent the contemplated reduction in cross-lake freight capacity."
---- John Niles, member, Puget Sound Freight Mobility Roundtable, presentation on 3-3-06.
Sound Transit's Long Range Plan specifies either exclusive busways or light rail on the center roadway of the I-90 floating bridge between Seattle and the Eastside via Mercer Island. This would be accomplished in Sound Transit Phase 2 along with the implementation of lane expansion in the outer roadway under the R8A plan.
R8A is an approved plan (with an issued Record of Decision) to establish four lanes in place of the existing three on the outer roadways. The additional lane in each direction would be HOV, including buses, carpools, and vanpools. R8A expands vehicle capacity in the AM peak by about 10%, and passenger capacity even more.
The center roadway of the I-90 bridge is now a reversal two lanes of HOV traffic flowing in the peak direction. It provides access to buses, carpools, vanpools, and (by special exception) general traffic destined for Mercer Island. R8A provides additional HOV capacity moving in both directions all day.
Now comes a problem because of Sound Transit's intent, amplified by the interest of many political leaders on both sides of the Lake who think light rail is a necessary, good service to build between Seattle and Bellevue. The current Sound Transit intent on the I-90 center roadway is to build either light rail tracks, or an exclusive busway that can be converted to train tracks for light rail later.
If Sound Transit succeeds in making the center roadway an exclusive transit guideway, the vehicle capacity of the bridge in AM peak will drop by 20% from its present capacity, and by over 30% from the R8A plan.
This reduction in vehicle capacity should be of specific concern to all citizens interested in regional mobility, especially the freight community, for whom I-90 is the main cross-lake bridge.
A better transit solution lies in establishing the center lanes as two-way HOV lanes with room for carpools and vanpools as well as buses. As shown on page two of the pdf, buses interspersed with other HOVs would maximize capacity. Buses crossing the bridge could follow a variety of routes in Eastside neighborhoods, providing better geographic coverage and superior service to a light rail mainline with stations served by feeder buses.
The HOV lanes could even be converted to HOT lanes, high occupancy toll lanes, a plan under which any available space between HOVs is monitored with cameras and computers, and allowed to be filled by toll-paying solo-driver cars and light trucks.
Of particular concern is this observation: If light rail tracks were to be placed in the center roadway and the trains operated as planned, there would be five miles of empty track between rush hour trains. See page 2 of the available pdf here. Cars and buses stuck in traffic on the outer roadway would look over at the tracks and see empty space most of the time. In occasional off-peak congestion, drivers would also see empty space on trains that are even farther apart than five miles.
In the better solution, a bus every 50 seconds on an HOV or HOT configuration would provide superior passenger carrying capacity, and provide space in between buses for other kinds of HOVs that would not need to use the outer roadways.
The I-90 bridge is owned by State of Washington. Sound Transit taking over the center lanes of this bridge with its contemplated low capacity transit-only busway and railroad scheme requires approval by State Government. Citizens interested in maintaining the I-90 bridge in a configuration with the greatest vehicle capacity and people-moving capacity should immediately make their views known to the Secretary of Transportation, the Governor, and their state legislators.
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Last modified: February 07, 2011