I-5/SR-432 Interchange Area

Purpose and Need Statement

May 2003

Problem Statement

The SR-432 and I-5 corridors are Highways of Statewide Significance and are the only such facilities in the Longview/Kelso urbanized area. SR-432 is on the National Highway System and connects I-5 to US 30 in the State of Oregon. As such, these corridors are of critical importance to the region and its economy as a major corridor for the movement of both people and goods.

During preparation of a Route Development Plan (RDP) for SR-432, several deficiencies were identified at and near the interchanges of SR-432 with Talley Way and Interstate 5 with SR-432. These interchanges are in immediate proximity to each other. Deficiencies include existing and future (20-year) traffic congestion exceeding both state and local standards. Truck traffic volumes along SR-432 are significant ranging as high as 31 percent of PM peak hour traffic. Near I-5, 16 percent of PM peak hour traffic is trucks.

Access from adjacent industrial land to the State Transportation System is poor. The interchanges encompass geometric deficiencies that do not meet existing highway design standards and have potential safety problems. In addition to traffic and geometric problems, the interchange area is significantly constrained by topography, wetlands, railroad and airport height/clearance limitations and other factors.

As traffic volumes grow along SR-432, the I-5 interchange area will become a bottleneck potentially constraining freight movement into and out of the Longview/Kelso industrial corridor, as well as the Port of Longview and destinations in northwestern Oregon.

Current and projected future problems include:

  • SR-432 is currently deficient between the Talley Way interchange and the I-5 interchange where there is a very short weaving area for traffic moving between the two interchanges. During the 20-year planning horizon, this weaving area will worsen impacting both travel time and potential safety.
  • Future traffic operational deficiencies are expected to develop during the next 20-years at:

The westbound SR-432 off-ramp at Talley Way

The SR-432 eastbound on ramp to I-5 southbound

The I-5 northbound off-ramp to Old Highway 99.

  • Additional safety concerns are expected as traffic volumes increase as there are several local connections within the I-5/SR-432 interchange vicinity that are deficient. These deficiencies are based on existing highway design criteria including:

The weave between the southbound-to-westbound ramp from I-5 to SR-432 and the westbound to northbound ramp from SR432 to Talley Way.

The merge between the eastbound to southbound ramp from SR 432 to I-5 and the Tally way onramp to eastbound SR432.

The merge between the northbound-to-westbound ramp from I-5 to SR-432 and northbound-to-westbound Highway 99 traffic

The merge between westbound traffic entering SR-432 from Talley Way and westbound SR-432 mainline traffic.

Poor intersection geometrics in the SE quadrant of the I-5/SR 432 interchange.

Alternatives Studied

Local access improvements were analyzed in the SR-432 Route Development Plan to serve the growing development in the SR-432 industrial corridor. These improvements may alleviate some but not all of the interchange deficiencies and are dependent upon resolving existing and future deficiencies at and near the I-5/SR-432 interchange.

Numerous alternatives were studied during the RDP process to resolve these deficiencies including:

  • Access ramp revisions,
  • Local improvements in lieu of interchange modifications,
  • Several new interchange concepts, and
  • Removal of the Talley Way interchange coupled with revisions to the I-5/SR-432 interchange to accommodate Talley Way traffic.

None of the alternatives studied was able to fully resolve the identified deficiencies and each had potential natural resource, right-of-way or highway geometric impacts associated with it that made it an unacceptable solution from a state and/or local perspective.

Purpose and Need

The purpose of this study is to identify a project that will:

  1. Resolve the existing and projected operational deficiencies to reduce vehicular conflicts and delays along SR-432 between the Cowlitz River and I-5.
  2. Resolve the existing and projected operational deficiencies to reduce vehicular conflicts and delays at the SR-432/I-5 and SR-432/Talley Way interchanges.
  3. Resolve the existing and projected operational deficiencies of the merge onto southbound I-5 from SR-432 eastbound.
  4. Resolve the existing and projected operational deficiencies of the off ramp from I-5 northbound to Old Highway 99.
  5. Resolve deficient roadway geometrics at the I-5/SR-432 interchange.
  6. Resolve deficient roadway geometrics on SR-432 between Talley Way and the I-5 interchange.
  7. Provide appropriate access to the State Transportation System.
  8. Reduce negative impacts associated with delays to regional and interstate freight movement between I-5 and the Longview and Kelso industrial corridors, as well as across the Lewis and Clark Bridge to the State of Oregon, consistent with planned or recommended local transportation improvements.

Purpose and Need Statementrev5-9 (3)