what we do


Designing connections that balance regional mobility and local access

From rural highway off-ramps to complex freeway interchanges, Parametrix helps agencies plan and design interchanges that safely and efficiently move traffic from one road to another. We help agencies with freeway and local operational analysis for highway and local corridors, and have provided analysis for numerous interchange justification reports (IJR), interchange modification reports (IMR) interchange access modifications, and corridor studies. Our staff have developed great working relationships with FHWA and state DOT staff and can guide you through the approval process.

I-5/Slater Road IJR | Parametrix
I-5/Slater Road IJR 
Ferndale, Washington
Client: Lummi Nation

The Slater Road interchange improvement project is a key transportation project to support planned economic development of the Lummi Nation. It will improve safety and access to I-5 for the Lummi Nation, City of Ferndale, and surrounding communities, as well as improve mobility on I-5 through the interchange area. Parametrix has led the Slater Road interchange project through the IJR process and preliminary design. The multi-jurisdictional project team includes the Lummi Nation, Whatcom County, WSDOT, FHWA, and the cities of Bellingham and Ferndale. In preparation for the IJR, and to support the alternatives screening analysis, Parametrix led the safety analysis using the HSM and iSATe tools for a study area which included arterials owned and maintained by multiple jurisdictions and the interstate.



  • US 550, NM 313 to NM 528

    US 550, NM 313 to NM 528

  • SR 410/Traffic Avenue Interchange

    SR 410/Traffic Avenue Interchange

  • 116th Interchange at I-5

    I-5/116th Street NE Interchange

  • I-84 Karcher to Franklin | Parametrix

    I-84 Karcher to Franklin

  • I-5/Slater Road IJR | Parametrix

    I-5/Slater Road IJR

  • I-84 Meridian Road Interchange

    I-84 Meridian Road Interchange