A new I-5 crossing
Since the late 1990s, Clark County planning efforts have consistently reflected the need for new I-5 crossings north of NE 134th Street. Locations from NE 139th Street to NE 219th Street were considered to relieve traffic congestion on the existing I-5 crossings and improve connections between neighborhoods.
As growth projections in the area changed and technology used for traffic modeling improved, traffic projections in the Salmon Creek area were refined making the need for a new I-5 crossing near NE 134th Street increasingly clear. No other option, including widening NE 134th Street, relieved congestion enough to meet county traffic standards on NE 134th Street.
Interchange options considered
Since 2002, the Salmon Creek Interchange Project team considered many ways to provide access to I-5 from the Salmon Creek area. Preliminary designs were compared based on criteria that included accommodating forecasted traffic demand; minimizing right-of-way impacts, potential environmental impacts, and project cost; and meeting community expectations. Through this process, an interchange that crosses over I-5 and provides movement in three directions at NE 139th Street was identified for further study in the environmental assessment.
Designing the recommended option
After identifying an interchange at NE 139th Street as the option that best addresses mobility and safety, the project team developed more specific interchange design options. The proposed design option is a new interchange that provides movement in three directions: a northbound on-ramp, a northbound off-ramp, and a southbound on-ramp (the interchange will be designed so that movement in the fourth direction, the southbound off-ramp, could be added in the future). Compared to other designs considered, this interchange design will:
- minimize environmental impacts to wetlands in the area
- reduce impacts to surrounding properties and roads
- improve traffic operations and allow for future improvements to I-5
- reduce the overall project cost.