CDM Smith

Scope Of Work

CDM Smith helped identify options to improve service and strengthen connections for transit, cars, trucks, bicycles and pedestrians on one of Seattle’s critical corridors. 

In November 2015, voters approved the “Levy to Move Seattle,” a 9-year, $930 million measure to improve safety and mobility for all transportation system users in and around the rapidly developing Emerald City. Aligned with Seattle’s 10-year “Move Seattle” strategic vision for transportation, the levy included funding for seven high-capacity transit corridor projects. One of the seven is the Roosevelt to Downtown corridor. The north-south corridor’s study area stretches approximately 8.1 miles, passing through burgeoning urban areas, from Northgate, Roosevelt, the University of Washington District and Eastlake to major technology, employment and medical centers in South Lake Union and Downtown Seattle.

CDM Smith was hired by the Seattle Department of Transportation (SDOT) to lead the Roosevelt High Capacity Transit Corridor project’s planning and conceptual engineering phases. The agency’s goal was to make transit service faster and more reliable on the corridor, improve pedestrian and bicycle access to transit, and decrease overall congestion. At the time CDM Smith began its study, SDOT had already identified bus rapid transit (BRT) and rapid streetcar service as possible solutions. SDOT tasked CDM Smith’s transit experts with analyzing these scenarios further to help SDOT identify its preferred corridor concept, which it would eventually submit to the Federal Transit Administration for funding support.

“Before evaluating the BRT and streetcar alternatives,” said Tim Boesch, AICP, principal project manager, “we needed to get a clearer picture of conditions along the corridor.” Boesch and the CDM Smith team began updating the city’s existing data, collecting large amounts of traffic, intersection, transit ridership, demographic and socio-economic information. CDM Smith then prepared a framework to screen the two alternatives. “Instead of performing a lot of modeling,” said Boesch, “we developed a qualifications-based analysis tool to compare the two modes against many areas of desired transit performance.” According to Boesch, this approach saved SDOT costs and ultimately helped the agency select BRT as its preferred alternative.

SDOT was interested in analyzing the different levels of BRT that it could implement while still effectively accommodating all other modes of transportation. Options included dedicated center- and side-running BRT-only lanes, basic King County Metro RapidRide express bus service, or a mix of targeted BRT and complete streets investments designed to align with SDOT’s budget. “Right-of-way was a significant challenge in planning this project,” said Boesch. “A lot of design challenges dealt with finding adequate space for bike lanes, car lanes, parking and dedicated transit lanes within the existing curb-to-curb width.”

Through an extensive public outreach program comprising open houses, stakeholder forums, neighborhood meetings and an interactive project website, CDM Smith uncovered the most-desired improvements. “The flexible approach we took ensured that all residents had a chance to weigh in,” said Bosech. For example, in one stretch of the corridor, the addition of new protected bike lanes to accommodate a high number of bicyclists would require the relocation of parking. “The neighborhood agreed bicycle facilities and a center turn lane were more important to them than on-street parking,” said Boesch. Feedback like this helped the city realize the importance of investing in “complete streets” improvements along the corridor. “Several people urged us to not deviate from transit-first solutions.”

Since CDM Smith determined that full center-running BRT would be too capital intensive for SDOT, the team instead put forth a series of targeted improvements at key locations to improve bus speeds. In addition, the initial BRT route was shortened on the north end to align with Sound Transit’s Roosevelt Link light rail station, while still providing service on the busiest parts of the corridor. The now-complete 10-percent block-by-block conceptual design package includes side-running bus lanes in key segments from Roosevelt to downtown Seattle, enhancing the corridor’s signal system to allow for traffic signal prioritization, and queue jump lanes at congested intersections to give buses first-priority at green lights.