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SR 510 Yelm Loop Phase 2 Improvement Project: Supplemental Environmental Assessment and Online Public Meeting – Transportation

WSDOT evaluated existing and forecasted traffic for 2023 and 2043.

Two traffic scenarios were evaluated:

  • Traffic conditions assuming the project is not constructed (No Build Alternative).
  • Traffic conditions with the new roadway constructed as a two-lane limited access/managed access road from the existing end of Phase 1 at Cullens Road to SR 507 (Build Alternative).
Map illustrating locations of existing Yelm Avenue route and proposed Yelm Loop route, from the intersection of SR 510 Spur and Mud Run Road at the western edge of the city to the intersection of SR 507 and 170th Street at the eastern edge.

No roadway currently exists in this area. The Project will provide a new and more direct connection between the existing end of the Yelm Loop to SR 507, and will allow traffic traveling through Yelm to bypass the busy business district on Yelm Avenue.

Travel times

By completing the Yelm Loop corridor, congestion would be reduced on Yelm Avenue as compared to the No Build Alternative. Regional traffic would experience less delay. An estimated 67% of regional traffic would use the completed Yelm Loop.

In the opening year (2023), traffic using the Yelm Avenue route would receive minimal time savings compared to the No Build Alternative, but regional traffic on the Yelm Loop route would see travel times reduced by over 40% (see Table).

In 2043, traffic is projected to experience more significant improvements compared to the No Build Alternative. Traffic using the Yelm Avenue route would see travel times reduced by approximately 40% in the eastbound direction and 21% in the westbound direction, as compared to the No Build Alternative. Regional traffic using the Yelm Loop route in 2043 would experience travel time savings of approximately 60% in both directions compared to the No Build Alternative.

Without construction of the project, traffic conditions would get worse, and most trips through the study area would take longer in the future than they do today.

Table illustrating projected PM peak hour travel times for 2023 (projected Build Alternative opening year) and 2043 (long-range horizon year), for both the existing Yelm Avenue route (No Build and Build Alternative) and the proposed Yelm Loop route (Build Alternative only). Travel times are shown for each route between SR 510 roundabout at Mud Run Road (west terminus) and SR 507/170th Street intersection (east terminus). In the opening year (2023), traffic using the Yelm Avenue route would receive minimal time savings compared to the No Build Alternative, but regional traffic on the Yelm Loop route would see travel times reduced by over 40%. In the horizon year (2043), traffic using the Yelm Avenue route would see travel times reduced by approximately 40% in the eastbound direction and 21% in the westbound direction, and regional traffic using the Yelm Loop route would experience travel time savings of approximately 60% in both directions compared to the No Build Alternative.

Local streets and intersections

With the completion of the Build Alternative, traffic using local roads to bypass downtown Yelm is expected to be reduced or eliminated. Additionally, downtown congestion would be relieved, though not eliminated. Yelm Avenue would serve predominantly locally destined traffic. Those who commute locally would have shorter travel times, and decreased congestion on Yelm Avenue would reduce the potential for crashes.

The Build Alternative would result in four local roads being converted to cul-de-sacs to reduce the number of intersections under the limited access designation of the corridor. Residents living adjacent to the new cul-de-sacs would have to alter their travel routes to access Yelm Loop and the surrounding local road network adding some additional travel time to their trips.

Freight

SR 510 and SR 507 are the only designated truck routes in the project area used for transporting goods to and through Yelm. Approximately 4% of the vehicles on SR 507 and 6% of those on SR 510 are trucks that must navigate the intersection of Yelm Avenue and First Street in downtown Yelm. Freight is often delayed due to congestion and difficulty making turning movements. With the completion of the Build Alternative, regionally destined freight traffic would be able to bypass downtown Yelm, making travel times more reliable and removing large trucks from the congested downtown area.

Multimodal improvements

Goals outlined in the City’s 2017 Comprehensive Plan specifically address improved access to public transit, and to pedestrian and bicycle facilities. The Build Alternative would be consistent with and help implement these goals by including new facilities for bikes and pedestrians.

The existing bus service to Yelm is currently focused on providing access to the ridership generators in downtown on Yelm Avenue. Intercity Transit’s Short- and Long-Range Plan (2018) includes a Yelm Express route that may utilize the Yelm Loop alignment to provide commuter access between Yelm and Lacey after the Yelm Loop is constructed. The Build Alternative would accommodate such future bus routes.

Safety

A total of 520 crashes occurred on Yelm Avenue in the study area over the five years between 2013 and 2018. Of those, 322 crashes (approximately 61%) involved rear-end collisions. An additional 14% were classified as entering at an angle, which occurs when a vehicle attempting to enter the primary travel way from a minor street approach is involved in a crash.

The data shows that approximately 66% of crashes on Yelm Avenue were types associated with congestion, including rear-end and sideswipe collisions. As traffic volumes along Yelm Avenue are expected to be reduced with completion of the Yelm Loop, and as no geometric changes along that road are proposed, it is anticipated that congestion-related crashes will also be reduced. As these two factors are primary influencers in the safety analysis, it is reasonable to assume that safety along Yelm Avenue will be as good or better than they are now.

As the proposed Yelm Loop has not yet been constructed, no safety data is available and safety analysis has not been conducted for the new segment of roadway.

For more information

To read more about the transportation analysis please see Section 3.2 Transportation (PDF 1.4MB).