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City of Des Moines
Transportation Gateway Project
Project Update:  July 28, 2009

Background
The Transportation Gateway Project entails upgrading two City arterials: S. 216th St between I-5 and 18th Avenue S and 24th Avenue S. between S. 216th St to S. 208th St.  The below map and graphic shows how the Transportation Gateway Project will eventually link with the surrounding land use and transportation system.

Map (Click for larger PDF)

This project will accommodate growth of Pacific Ridge area as it transitions to more intensive business park, multi family and retail uses.  This growth is expected to generate up to 35,000 vehicles per day. 

Generally, the new roadways require widening to nearly 100’, adding two lanes in each direction, center medians and turn lanes, bicycle lanes, and ADA accessible sidewalks and bus stops. Storm water will be collected and treated to protect water quality.   Need for these capacity improvements has been documented in the update to the City of Des Moines Comprehensive Transportation Plan, including the S. 216th Corridor Study and the 24th Avenue S Corridor Study.  More detail on the project can be found in previous project updates (see links at the bottom of page).

The first open house held on April 14, 2009 offered citizens an opportunity to review development plans in the area, understand the related transportation issues, as well as engage in meaningful dialog to about designing the project.  Design objectives for the project were defined to assist in making these roadways complete streets  by improving mobility and safety for vehicular traffic as well as pedestrian, bicycle and transit users.   Several concerns were express about the project’s impact on commercial access and residential properties.  A second open house was held on June 2, 2009 where public commets were received on alternative alignments.

Alternatives
The City developed alternatives for the necessary roadway widening on 24th Avenue S and S 216th Street within the project limits.  A typical roadway cross-section will accommodate a 5 lane roadway with bicycle lanes, curbs gutters, sidewalks and planter strips.  The range of alternatives included expansion of the roadway using:  1. A conventional alignment that is symmetrical to the roadway centerline; or  2. Applying a offset alignment concept that allows the right of way to meander off the current centerline to minimize impacts to developed properties and utilities.  The alignment alternatives were refined using a detailed base map survey that accurately depicts local conditions.

Best Fit Alignment
Based citizen input and engineering study and direction from the Des Moines City Council, an “offset” alignment concept was selected as a “best fit” for the surrounding neighborhood while minimizing potential impacts on developed properties.  Over the course of the summer, the City’s consultant will utilize the “offset” alignment concept to developing plans for these roadways in preparation for issuing a design report.  The report will refine project road design elements including a geotechnical report, curb, gutter and drainage plans, roadway and lane striping details, signalization improvements, utility coordination, a survey of cultural/historical features, environmental assessment details, right of way requirements and project cost estimates tied to proposed improvements.  This work will consider project phasing as a means towards implementation. 

The City is coordinating with a variety of other agencies and utilities, including the City of SeaTac, to make sure the improvements mesh well with area plans.

Civil Engineering Services & Schedule
The adopted 2009 Capital Improvement Plan programmed the start of engineering to upgrade S. 216th St and 24th Avenue S as illustrated in the General Schedule (PDF).  Following review of the design report this fall, and City Council approval, the project will advance into final design in 2010 including environmental work, right of way plans and contract documents.  As noted below, construction phasing is subject to available funding.

Alternatives were evaluated this spring resulting in selection of a roadway design concept.  A design report will be prepared in the fall detailing the project scope which will guide the project through preparation of final contract documents.  

Funding
The engineering work is funded, in part, with a loan from the Washington State Public Works Trust Board as well as development fees and arterial road funds as approved in the City’s Capital Improvement Program.  As design progresses, the City is actively seeking additional funding for right of way and construction. Development will contribute a fair share to the improvements on South 216th Street and 24th Avenue South, through frontage improvements, utility undergrounding and off-site mitigation.

Questions?
Persons with questions or comments are urged to contact the Len Madsen, Project Manager at gatewayinfo@desmoineswa.gov.

Gateway Web Archives:
Update: May 12, 2009
Update: April 7, 2009
Update: April 1, 2009
Update: February 6, 2009
Update: January 19, 2009