Based on performance, the recommended mid-term (2035) concept is Improvement Concept #1 – Five Roundabouts, one each at Covington Way Southeast, 164th Avenue Southeast, SR 18 westbound & eastbound interchange ramps, and 168th Place Southeast. This concept was selected because it achieved the highest score in the evaluation criteria matrix. A few highlights where the Five Roundabout concepts outperformed the other concepts were:
- Consistency with Target Zero – roundabouts have a record of significant reductions of serious and fatal crashes.
- Bicycle/Pedestrian Level of Traffic Stress – would include a 10-12 feet wide shared use path.
- Consistency with Complete Streets – slower speeds with roundabouts and inclusion of shared use path would be an improvement.
- Potential Phasing for Construction – would allow for a phased approach during construction.
- 2035 Traffic Performance – excellent performance at all intersections.
Specific design details including active transportation facilities to meet the WSDOT Complete Street’s requirement will be determined in the design phase.
Due to the high planning-level cost estimate, the Five Roundabout recommendation will need to be phased. The first roundabout that could be constructed is Covington Way Southeast. Subsequent project elements will likely construct roundabouts from west to east in multiple phases.
The goal of WSDOT’s Complete Streets program is to build out a comprehensive active transportation network on the existing state highway system. As WSDOT makes regular improvements to its rights-of-way, it will update these facilities to safely accommodate a wide variety of pedestrians and bicyclists. Complete Streets applies to state projects greater than $500,000 on highways where access is managed through permitting, and when located within a population center, in a vulnerable/overburdened community, and/or on or near tribal lands. See WSDOT’s Complete Streets website for more information.
Planning Level Cost-Estimates
A planning level cost-estimate range is $38 to $48 million. The estimate range is based on minimal/no-design (<5%) and is in current-year (2023) dollars. A design phase will be necessary to develop a detailed cost-estimate based upon the various design, construction, and environmental components required to construct the recommended concept.
Upon completion of the SR 516 – Covington Study, WSDOT will work with the city and local partners to seek funding for design and construction of the recommended improvement concept. Given the size and scope of the recommended five roundabouts, it will likely be necessary to phase the proposed project elements during the early design process, given the high total cost.
The pursuit of grant and/or state or federal funding will likely be a multi-year process and it is expected that funding for implementation will need to come from multiple sources (local/regional/state/federal). The Puget Sound Regional Council (PSRC) manages several Federal Highway Administration and Federal Transit Administration grant funding programs that could be sources of funding for this recommendation. More information can be found on the PSRC’s website.
WSDOT will work with the City of Covington and other interested parties to ensure these recommendations are incorporated into local and regional plans as appropriate. The city’s ongoing update to the local comprehensive plans provides an opportunity to include these recommendations.