If your project connects to Montana’s state highway system, SIAP provides a structured review to ensure safety, efficiency, and sustainability. This process helps developers coordinate with MDT, navigate permitting and environmental requirements, and understand cost-sharing responsibilities for necessary roadway improvements.
What is SIAP?
SIAP is MDT’s coordinated review process for projects initiated outside MDT—such as commercial, residential, or industrial developments—that may impact state highways.
It ensures appropriate highway access and protects taxpayer investments by evaluating traffic, drainage, environmental effects and defining mitigation requirements.
How It Works
- Most projects are reviewed and approved by MDT District and Maintenance staff.
- Complex projects requiring multiple technical reviews are nominated for SIAP and assigned a dedicated SIAP Coordinator—your single point of contact for questions and updates.
Timelines
Review times vary by project complexity. MDT typically responds 4–5 weeks with initial feedback on submitted materials. Some projects may require multiple review iterations to ensure safety and compliance.
How to Get Started
If you haven’t already, contact your local maintenance chief to help get you started – find yours in the district office directory.
Frequently Asked Questions
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.
- Submit a Permit Application & Environmental Checklist
- Optional Start-Up Meeting
- Technical Review by MDT
- Design & Approval
- Construction Authorization
- Construction Oversight & Inspection
- 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: