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The City of Vancouver’s Northeast 137th/138th Avenue Improvement Project, from Northeast 28th to Northeast 49th Street, was completed in late 2013. The need for this major street project has been recognized as part of the City's ongoing Transportation Improvement Plan for many years. Extensive community involvement and outreach and coordination with emergency service providers, C-TRAN, Evergreen School District and Waste Connections was essential for a successful completion.
Construction contract -- lowest responsive bid -- for this project was $6.7 million. Total project cost, which includes right-of-way acquisitions, design and permitting, was previously estimated at about $14.6 million. Latest estimate for the total project is less than $13 million. Funding is provided by: $3.25 million in federal grants awarded through the Washington Department of Transportation; $3.1 million in Washington Transportation Improvement Board funding, and $8.24 million in City of Vancouver local development traffic impact fees and bonds.
Planning studies, public outreach and preliminary engineering for the project formally began in 2004. Final engineering began with Council award of a consultant contract in December 2007. Public outreach continued though the formal design phase. A 'Value Engineering' study recommending the existing roadway design was conducted in February 2009. By June 2009, the design had matured enough for the right-of-way acquisition process to begin. The right-of-way acquisition, environmental permitting and design work was completed in the spring 2012, and construction started in late August/early September 2012. Work was completed in late 2013.
Approximately 13,000 vehicles per day currently use the 137th/138th Avenue corridor. That number is expected to double by the year 2030. The overall goal for the project was to improve safety, increase traffic carrying capacity along this arterial roadway, bring the street section up to urban standards, and reduce traffic backups. The immediate area has limited options for northbound and southbound through traffic, with the nearest alternatives being Northeast 112th Avenue to the west and Northeast 162nd Avenue to the east.
Prior to this project, the existing 137th/138th Avenue roadway between Northeast 28th and 49th streets was a two-lane rural road, with substandard pavement conditions, dirt shoulders, and ditches for stormwater runoff. A majority of the corridor had no center turn lanes, bike lanes, sidewalks or street lights. In addition, there were some sight distance issues due to side street intersections and the narrow roadway, which also serves many residential driveways.
At the start of the project, the design option that was preferred for maximizing through traffic and creating safe left-turn movements was a five-lane section, allowing for two through lanes in each direction and a continuous left-turn lane. (Two through lanes in each direction would create the necessary gaps in traffic to allow the high number of left-turn movements.) However, with construction and right-of-way acquisition cost estimates of $23.1 million, a five-lane section was not economically feasible. With 34 homes to be purchased for a five-lane design, costs for right-of-way acquisition alone were estimated at $11 million.
The design effort then shifted to a three-lane section, again allowing for a continuous left- turn lane. In this case, the construction and right-of-way costs were more manageable. However, traffic modeling showed that a three-lane section with one through lane in each direction would not create enough breaks in through traffic to safely allow the volume of left-turn movements being made.
In analysis, the three-lane section level-of-service failed for both street crossings and driveway operations due to a combination of overall traffic volumes coupled with high demands for left turns. In addition, the three-lane section would have required acquisition of 11 homes. With average purchase prices of $200,000 at the time and added relocation costs for up to $15,000 per relocation, this three-lane option was estimated to have right-of-way acquisition costs alone of almost $2.4 million, and, again, would have failed to meet level of service requirements.
A 'Value Engineering' (VE) study was conducted looking for different ways to accomplish the goal of increasing capacity through the reduction/elimination of left turns and keeping costs at a manageable level. That study recommended installing a raised median through the majority of the project and using roundabouts to accommodate left-turn movements. This reduced the number of total property purchases for right-of-way to only four. It also would minimize left-turn conflicts throughout the corridor and reduce traffic backups.
In the final design, a roundabout was placed at the intersection of NE 39th Street in lieu of a traffic signal, similar to the existing roundabout at Northeast 49th Street. Additional roundabouts were placed at Northeast 44th and 32nd streets in order to minimize the amount of 'backtracking" for those along the corridor who needed to make a left turn, and to provide a safe place to get turned around instead of forcing u-turns at intersections.
The recommended improvement for the NE 137th/138th Avenue Project includes roundabouts at NE 32nd Circle, NE 39th Street, and NE 44th Street. Among their benefits, roundabouts provide turn-around options to minimize out-of-direction travel for drivers prevented from making left-hand turns along the corridor improvement area. In terms of safety and efficiency, roundabouts reduce many of the safety hazards associated with traditional intersections and lower overall vehicle delays, which reduce emissions and add capacity. They increase safety by limiting vehicle movements to right turn only. Eliminating left turns across traffic, common in traditional intersections, reduces the frequency and severity of collisions. Roundabouts planned as part of the project include:
Please note: Recognized best civil engineering design practices for roundabouts call for a vertical feature in the middle of the roundabout. This is to provide visual cues as positive notice to drivers at all times of day that the roundabout is there and must be driven around, not driven through. Landscaping and hardscaping are included for safety reasons and, as a side benefit, help enhance the neighborhood.