The Washington State Department of Transportation (WSDOT) has a new roadside policy found in the Roadside Policy Manual. Roadsides are the green infrastructure that contributes to the transportation system. The new policy emphasizes preservation of existing desirable vegetation and restoring the roadside using native vegetation in a way that is maintainable. The new policy also contains guidelines for tree replacement ratios if a project removes trees. Trees and large shrubs play a big part in the functions on our roadsides.

street trees

This year WSDOT signed an updated agreement with the Association of Washington Cities on City Streets as Part of State Highways. It provides guidelines on maintenance responsibilities between WSDOT and Washington cities. For example, landscaping beyond the baseline (found in the Roadside Policy Manual), permanent irrigation, and any decorative items are the city’s responsibility. The new manual has chapters on community gateways and roundabouts that will be of interest to communities.

The Roadside Policy Manual develops vision and instructional policy for:

  • Complying with legal obligations and commitments, and obtaining environmental permits and approvals;
  • Preservation of roadside design, construction, and maintenance;
  • Achieving roadside sustainability through the use of native plants, integrated vegetation management, and a long-term management approach;
  • Developing the roadside to provide functions such as stormwater, erosion control, weed control, and slope stabilization; and
  • Providing the highest benefit at the lowest feasible cost.