This webpage provides information on the SIAP review process for non-MDT projects that impact MDT facilities as nominated by MDT District/Area Office and Maintenance officials.

SIAP Project Reviews

Most proposals are reviewed and approved directly by District and Maintenance staff. Projects requiring multiple review services involving MDT Headquarters (HQ) staff (Traffic, Hydraulics, Construction, Surfacing, Right-of Way, Geotech, Environmental, or Legal) are nominated for coordinated SIAP review. SIAP projects are assigned an SIAP Coordinator to act as a single point of contact to facilitate completion of the project review.

SIAP review timelines are based on complexity of the proposed project. Generally, MDT requests 4-5 weeks to return comments on material submittals or requests for information. Material reviews can require multiple review iterations.

For more SIAP information please visit the Developer’s Guide to the Systems Impact Actions Process.

Frequently Asked Questions

The System Impact Action Process (SIAP) ensures that new private or public developments connecting to or affecting Montana’s state highway system are reviewed to keep roads safe, efficient, and sustainable. It provides a clear path for developers to coordinate with MDT while identifying necessary roadway improvements and cost-sharing responsibilities.

SIAP evaluates traffic, drainage, and environmental effects of proposed projects, defines mitigation requirements, ensures appropriate highway access, and protects taxpayer investments through equitable cost-sharing.

  • Generates 150 or more trips per peak hour
  • Requests new or modified highway access
  • Involves land use or zoning changes that increase highway impacts
  • Requires engineering solutions (e.g., turn lanes, signals, access modifications)

If impacts are minimal and no off-site improvements are needed, the project may proceed under a standard permit review instead.

  1. Submit a Permit Application & Environmental Checklist
  2. Optional Start-Up Meeting
  3. Technical Review by MDT
  4. Design & Approval
  5. Construction Authorization
  6. Construction Oversight & Inspection
  7. Permit Issuance

  • Environmental Checklist
  • Traffic Impact Study
  • Drainage/Hydraulics Report
  • Final roadway and signal plans
  • Financial Guarantee (if required)
  • As-built drawings and improvement cost summary

Timelines vary by project complexity—typically several weeks to a few months—depending on:

  • Quality of submitted materials
  • Coordination between MDT, consultants, and local governments
  • Need for mitigation agreements or environmental clearances

Each MDT District Office has local staff to help scope, review, and coordinate SIAP projects.

For statewide coordination, contact:
LeRoy Wosoba, SIAP Supervisor, Asset Strategy, Operations and Maintenance.

Helpful Links: