Interchange Studies

Interchange Justification

When the Wyoming Department of Transportation considers adding, moving, or modifying an interchange on the interstate system, the Federal Highway Administration (FHWA) requires that certain federal requirements be addressed regarding the need for and potential effectiveness of the proposed improvements. The following are the basic applicable requirements of FHWA’s Policy for Interchange Modification, and actions that would need to be taken by WYDOT to address them:

• Do existing roads provide adequate access to the proposed development?
  • WYDOT will investigate whether the proposed development area can be safely and efficiently accessed by lengthening service roads and/or other routes in the area.
• Will the proposed interchange negatively affect the safety and operation of the interstate?
  • WYDOT will conduct traffic studies along the interstate in the vicinity of the proposed improvement, including existing and future (projected) vehicle counts, and study how this could affect the adjacent interchanges, roads and streets.
• Will the proposed interchange connect to a public road only, and will it provide for all traffic movements? Will the proposed modification be designed to meet or exceed current standards for federal-aid projects on the interstate?
  • WYDOT will examine whether the proposed interchange’s configuration will fully address future traffic needs. WYDOT must show that the new interchange will be designed to meet or exceed all current traffic design standards.
• Will the proposal consider and be consistent with local and regional land use and transportation plans?
  • WYDOT will consult with local governments regarding their land use and transportation plans, and evaluate the relationship of the proposed interchange to the plans. Before final approval, FHWA will require that the request for the interchange or modification be consistent with the local transportation plan.
• If the request for a new or modified interchange is generated by new development, WYDOT and the local governments must show coordination between the development and the proposed transportation system improvements.
  • WYDOT can provide traffic analysis showing the number of trips generated by the proposed development, the impact they could have on the existing roadway system, and how the modified interchange would manage the new traffic patterns.
• Will the request for a revised interchange include information relative to federal planning requirements and environmental issues?
  • WYDOT will be required to provide information showing our intent to address all planning and environmental issues required by the National Environmental Policy Act. Final approval is contingent upon proper evaluation of the natural and physical environment (air, water, geography, and geology) as well as the relationship of people with that environment (health and safety, jobs, housing, schools, transportation, cultural resources, noise, and aesthetics) in relation to the construction of the proposed interchange.

An example of a typical interchange modification report can be found at the link below.

FHWA’s access policy statement

Please contact WYDOT’s Planning Program for additional information.