Adopted Level of Service Standards for Regionally Significant State Highways

Last Updated: 
Mar 24, 2017

In compliance with 1998 amendments (HB 1487, the “Level of Service Bill”) to the Growth Management Act (GMA) the Puget Sound Regional Council Executive Board adopted level of service (LOS) standards for regionally significant state highways in the central Puget Sound region. Regionally significant state highways are state transportation facilities that are not designated as being of statewide significance (also called non-HSS).

Level of Service Standards

This table (along with the map) explains the level of service standards.

Tier LOS Standard Description
1 LOS "E/mitigated" Tier 1: For this process, the "inner" urban area is generally defined as a 3-mile buffer around the most heavily traveled freeways (I-5, I-405, SR 167, SR 520, and I-90), plus all designated urban centers (most are located in the freeway buffer already). The standard for Tier 1 routes is LOS "E/mitigated," meaning that congestion should be mitigated (such as transit) when p.m. peak hour LOS falls below LOS "E."
2 LOS "D" Tier 2: These routes serve the "outer" urban area - those outside the 3-mile buffer - and connect the "main" urban growth area (UGA) to the first set of "satellite" UGA's (e.g., SR 410 to Enumclaw). These urban and rural areas are generally farther from transit alternatives, have fewer alternative roadway routes, and locally adopted LOS standards in these areas are generally LOS "D" or better. The standard for Tier 2 routes is LOS "D."
3 LOS "C" Tier 3: Rural routes are regionally significant state routes in rural areas that are not in Tier 2. The standard for rural routes is LOS "C," consistent with the rural standard in effect for those routes once they leave the four counties in the PSRC region, such as SR 530 entering Skagit County.


The LOS standards do not change within a city. For example, the change from Tier 1 to Tier 2 on SR 516 occurs at the Kent/Covington city limit boundary.

The LOS will be measured consistent with the latest edition (preferred) of the Highway Capacity Manual and based on a one-hour p.m. peak period.


PDF files are formatted for 11×17 printing.

Level of Service Standards for State Ferry Routes

LOS standards for the regionally significant state ferry routes (Fauntleroy-Vashon-Southworth and Pt. Defiance-Talequah) are the same as the existing WSDOT HSS ferry standards (ferry boat wait).

How Level of Service Standards Will Be Used

WSDOT will use the LOS standards to trigger a capacity deficiency analysis on regionally significant state routes for the State Highway System Plan. The State Highway System Plan process evaluates and recommends improvement strategies for the state highway network. Mobility strategies considered by WSDOT include capacity expansion, HOV lanes, access management, etc.

The Regional Council will use the LOS standards for regional transportation planning to gauge the performance of the system.

Local Compliance With Requirements

Cities and counties are required to include the LOS standards for all state routes in the transportation element of their local comprehensive plans. The Regional Council certifies the transportation-related provisions in local comprehensive plans, and staff reviews the plans to ensure that LOS standards adopted by PSRC for regionally significant highways (non-HHS) and LOS standards adopted by WSDOT for statewide significant highways (HSS) are included.

Local jurisdictions should review their plans during plan amendment and update cycles and ensure the adopted LOS standards in their transportation elements are consistent with the LOS standards for non-HSS and HSS state routes.

The Regional Council will measure the LOS for regionally significant state highways on a one-hour p.m. peak period basis. For its own purposes, a local jurisdiction may use its own methodology for analyzing LOS for those highways, but those LOS standards must be consistent with the Highway Capacity Manual LOS criteria. For example, where the regional LOS standard is “D,” a local jurisdiction may use an alternative methodology (such as average travel speed, intersection delay, etc.) for calculating a level of service of “D” as long as it is consistent with the Highway Capacity Manual.

While state law clearly exempts highways of statewide significance (HSS) routes from local concurrency regulation, it is not clear whether GMA applies concurrency to state-owned facilities that are not of statewide significance. These regionally significant state highways must be addressed in local comprehensive plans, have LOS standards set regionally, but the law is silent in terms of including or exempting them from local concurrency rules. Therefore, each local jurisdiction, with assistance from its legal staff, will decide how to respond to the regional standards. If the regional LOS standard is already compatible with the local standard previously set, then the local jurisdiction may decide to do nothing other than acknowledge the regional LOS standard in its comprehensive plan. Other options for local jurisdictions include amending its existing concurrency program to reflect the newly established regional LOS standard, modifying its local concurrency program to make it more flexible with regard to regionally significant state highways, or removing the state highway from the local concurrency program.

Mitigation Strategies

The LOS standard for the central urban Tier 1 routes introduces mitigation when the LOS along a roadway falls below “E.” The mitigation strategies document describes examples appropriate for Tier 1 regionally significant state highways that do not meet the established LOS standard. Regional Council staff provide these strategies for informational purposes only. While PSRC may plan for potential mitigation strategies as part of long-term regional planning, decisions on what strategies are appropriate for any particular situation will be made by WSDOT or the local jurisdiction on a case-by-case basis.

Level of Service Standards for Highways of Statewide Significance

The LOS standards for Highways of Statewide Significance (HSS) are set by WSDOT. The current standards are a Congestion Index of 6 in rural areas (outside urban growth areas) and 10 in urban areas, measured using a 24-hour methodology. Congestion Index values of 6 and 10 are approximately equivalent to LOS “C” and “D,” respectively.

System Updates and Amendments

As traffic volumes and utilization changes, a roadway’s characteristics may no longer fit the LOS tier it is currently assigned. As the characteristics of the roadway change, the next LOS tier may better define it. It is the responsibility of the local jurisdiction affected by the roadway to contact the Regional Council to request the LOS adjustment and coordinate concurrence with any other jurisdictions or agencies that may be affected by the change. Because all routes in question are state owned facilities, the Washington State Department of Transportation must be in agreement with any proposed adjustments before one will be approved.

If all parties are in agreement the change will simply be made as the defined LOS parameters state. The PSRC website will be updated with the appropriate maps and it will be up to the jurisdiction to contact the Regional Council to update or amend their comprehensive plan if necessary.
Any amendments or changes to the LOS tier definitions will require Transportation Policy Board Action. The defined LOS assignments will be reexamined in coordination with the Regional Transportation Plan Update and Congestion Management Process.

Local Concurrency

The Washington State Growth Management Act (GMA) requires that transportation improvements or strategies to accommodate development be available when the impacts of development occur. “Concurrency” for transportation facilities is defined in the GMA and the Washington Administrative Code to mean that any needed transportation improvements or programs be in place at the time of development or that a financial commitment exists to complete the improvements or strategies within six years.