Archive for October, 2010

King County now has all the funding needed to replace the South Park Bridge (16th Av. S. in Seattle’s South Park neighborhood).  The 79-year old drawbridge closed June 30th of this year due to poor structural safety, requiring a 2-mile detour across the 1st Av. bridge (Highway 99) to access this neighborhood.

The south half of Seattle has a longstanding east-west transportation deficit.  West Seattle neighborhoods and Southeast Seattle neighborhoods exist in isolation from each other, separated by steep hillsides and the industrial valley, with its Duwamish River, railroads, Interstate 5, and most of all, Boeing Field (King County International Airport).  The general aviation airport’s 10,000 foot long runway prevents any east-west travel for over 2 miles.  This results in a three-mile gap with no exits from I-5.  There were only three crossings of the Duwamish River in Seattle (currently two): The upper and lower Spokane Street crossings, the 1st Av. bridge, and the now closed South Park Bridge.  The result is that West Seattle and Southeast Seattle aren’t socially or economically connected – all connection goes through downtown Seattle or to freeway network.   The south half of Seattle is fragmented and isolated, and not coincidentally, poorer than the north half of Seattle.  The opening of Link light rail , from downtown Seattle to Sea-Tac airport via Southeast Seattle, brought home this point to me.  As a West Seattle resident, there are no connecting buses that I can take to the light rail line in Southeast Seattle.  A transit user must travel north to downtown, and then back south on the rail line.  But I don’t blame King County Metro for this predicament.  There are no buses because there are not even roads.   The only roadway paths, south of the Spokane Street Viaduct, are long and circuitous, requiring a great many counter-intuitive turns. 

My proposal: construct the replacement South Park bridge on a S. Cloverdale alignment (east-west) instead of the previous 14th Av S. alignment (north-south).  Then extend the new roadway, South Cloverdale Way, in a tunnel under Boeing Field, a bridge over the mainline rail tracks and I-5, connecting to the existing S. Cloverdale Street, two blocks north of the Rainier Beach Link rail station.  This 1.4 mile roadway would provide a direct seamless travel path from Southeast Seattle (near Rainier Beach) to South Park and White Center at the southern edge of West Seattle.  An interchange could be created at the I-5 overpass, with a freeway bus station.  The alignment and surrounding can be seen on this Google Map application.
View Proposed S. Cloverdale Way in a larger map

South Cloverdale Way would be built as a complete street, with one automobile lane in each direction, a bi-directional cycle track, and concrete curbs and sidewalks. Near intersections and in congested areas, dedicated turn lanes and transit/HOV lanes would be included.  The new route would include all-day 15-minute frequency transit service from White Center to Rainier Beach via South Park.  Metro route 60 would be divided into two, and the White Center-South Park segment would be extended along the new South Cloverdale Way to Rainier Beach, serving the Link rail station and the neighborhood center.  The roadway, transit service, and separated bicycle access would knit together these sections of the city, providing opportunities for exchange and growth, and create the conditions for building great city neighborhoods along the southern edge of Seattle.


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Sound Transit, the agency responsible for regional rail and bus transit in Seattle’s Puget Sound region, has issued a request for comments on the scope of an upcoming Alternatives Analysis for the North Corridor.   The ST2 funding package included an extension of Link light rail through this corridor, from Northgate to the Lynnwood Transit Center.  However, to apply for federal funding, ST must perform an Alternative Analysis.  I submitted the following comment to Sound Transit, and I recommend that you also make your opinions heard.

The Alternatives Analysis should include evaluation of an elevated Light Rail route primarily in the SR 99 alignment. In particular, I recommend an evaluation of an all elevated alignment turning westbound onto Northgate Way NE, curving across the Washelli Cemetery, northbound in the SR 99 alignment to approximately 220th Av SW, and following the Interurban Trail alignment to the Lynnwood TC.

Design of high capacity transit in the Puget Sound region must balance between two conflicting objectives: fast regional service, and providing access to neighborhoods.

In an analysis of urban rail systems in North America (written up here and accessible here) , I found that highest ridership density was correlated with shorter station spacings, even with lower speeds. Providing users with more places to access the system, particularly on foot, resulted in higher ridership. In light of this, a SR 99 alignment will bring light rail stations within walking distance of more people and destinations than an I-5 alignment through this corridor, and thereby provides a more useful and well-used system. Additionally, an I-5 alignment will result in stations in which a large portion of the walkshed is consumed with freeways, reducing ridership potential. The problems with this arrangement are found here: http://www.publicola.net/2010/01/25/rule-1-dont-put-a-light-rail-station-next-to-a-freeway.

However, the north corridor is a segment of an envisioned transit route between Everett and Seattle. The route’s usefulness for longer regional connections depends on its speed. If the corridor is built in an SR 99 alignment, the speed must nearly match the proposed speed of the I-5 alignment. I would consider Lynnwood TC to Westlake travel times of 25 minutes optimal, 30 minutes reasonable.

The Alternatives Analysis should include a thorough evaluation and comparison of this SR 99 alignment with the conceptual I-5 alignment in the ST2 proposal, in regards to station locations, ridership, TOD potential, travel times and environmental impacts.

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