A summary of the draft recommendations in the SR 167 Corridor Plan Report:
Today’s SR 167 has six lanes north of SR 18 and four lanes south of SR 18.
Plan Overview
Add One Lane in Each Direction, as outlined below:
The corridor plan recommends adding a northbound and southbound lane the length of the highway between I-405 in Renton and SR 161 in Puyallup.
- Between I-405 and SR 18, the new lanes would be operated as general-purpose lanes to improve traffic flow.
- South of SR 18, the added lanes would be operated as high-occupancy toll (HOT) lanes and would connect to the existing HOV/HOT lanes in King County.
- Additional auxiliary lanes would be added in two locations (shown on map). Auxiliary lanes, also called add-drop lanes, begin at one interchange and end at the next interchange. Auxiliary lanes help reduce merging conflicts by giving drivers more space to exit and enter the highway which improves traffic flow and safety.
- An additional recommendation is to add the “missing ramps” to the SR 167/SR18 interchange. Ramps would be added from northbound SR 167 to westbound SR 18; and from eastbound SR 18 to southbound SR 167.
The existing right of way is sufficient to build one lane in both directions in most places; however, additional land will be needed for stormwater runoff and wetland mitigation. In some cases, a significant amount of right of way could be required. The lanes would be built in stages as they are funded. Below are details of the recommendations and priorities: |
 |
| Summary of the recommendations in the SR 167 Corridor Report. See Larger Map |
Priorities for Funding and Implementing the Projects:
Complete the HOV lanes on SR 167 from I-405 to SR 410, as follows:
- Add a southbound HOV lane from S 277th to 8 St E
This project is already being designed and has partial funding for construction.
- Add a northbound HOT lane from 15th Street NW to 8th Street E
This project would complete the SR 167 HOT lanes in King County and is currently unfunded.
- Add a northbound and southbound HOT lane between 8th Street E and SR 410
No funds have been identified for this improvement. Completing the HOT lane system by extending the HOT lanes to SR 410/SR 512 in Pierce County is a high priority for WSDOT.
Build southbound segments to address traffic “bottlenecks”:
WSDOT proposes to build the lanes incrementally as funding becomes available, beginning with the southbound sections that will provide congestion relief in bottleneck areas. The worst traffic congestion on SR 167 is in the southbound direction during the afternoon peak periods. Results of an extensive analysis concluded that adding a southbound lane between S. 180th Street and S. 277th Street would provide the greatest benefits to traffic flow in the near-term.
Given the number of trucks using SR 167, highway designs should include wider lanes on the curves of interchanges and longer ramps for trucks to accelerate before merging with mainline traffic.
The recommendations also encourage the addition of express and local transit service and other transportation demand management strategies to provide more transportation options to address the growing needs in the corridor.
Costs
The preliminary estimated cost to add one lane in each direction of SR 167 between I-405 and SR 161 is $1.5 to $2.2 billion (2007 CEVP dollars).
These costs reflect the rising costs of construction and the Green River Valley’s geologic history. The presence of wetlands, liquefiable soils, and the difficulties of retaining and treating stormwater in this flood-prone area contribute to higher than average construction costs.
2030 and Beyond: Proposed Recommendations
The following recommendations are proposed for the vision beyond the year 2030. They are not included in the 20-year plan’s recommendations, and therefore, are not shown on the map. They are unfunded.
Add a second lane to the SR 167 corridor from I-405 to SR 512
Future projections, including truck traffic, indicate the need for a total of 10 lanes on SR 167, so the recommendations include accommodating an ultimate footprint of 10 lanes by preserving right of way for interchange and bridge expansion. There are 54 bridges and 14 interchanges on SR 167 from I-405 to SR 410.
Although there was interest in adding two new lanes each way, the larger footprint would require that most, if not all, bridges and overpasses be rebuilt, including three major interchanges, which would add $7 billion or more (planning-level cost estimates) for all the improvements.
Rebuild three major interchanges:
- 180th Street Interchange
- SR 18 Interchange
- SR 410/512 Interchange
It is recommended that the new lanes should be designed to allow for a possible conversion to HOT lanes in the future. That would require more width to allow for a four-foot buffer between the HOT lanes and the regular lanes. The vision is to have at least one northbound and southbound HOT lane between I-405 and SR 410.