Environmental Reevaluation Document  

The environmental reevaluation for this project was finalized on July 31, 2025. The document can be viewed and downloaded on the Public Hearing Tab, along with materials presented at the Public Hearing on June 25, 2025.  

 

Planned Improvements

We are designing improvements for Interstate 15 (I-15) through St. George, Utah, to accommodate the area’s long-term transportation and mobility needs. Improvements will include the following:

  • Widen northbound and southbound I-15 from two lanes to three lanes between Bluff Street (Exit 6) and St. George Boulevard (Exit 8)

  • Replace structures over 100 South and raise I-15 as needed

  • Replace structures over 700 South and raise I-15 as needed

  • Raise I-15 and construct new structures over 400 East and 900 South to establish new local connections
    under I-15

  • Coordinate the realignment of several utilities and installation of new utilities

  • Improve various drainage facilities along and under I-15

  • Design improvements at 700 South to facilitate a future interchange

A reevaluation of an October 2023 Environmental Assessment (EA) iwas completed to incorporate the addition of the new overpasses and local connections at 400 East and 900 South, which were not part of the original environmental document. A public hearing was held June 25, 2025. 

The reevaluation includes additional noise analysis related to the new overpasses. After the public hearing, identified impacted property owners and tenants will be asked to vote to help determine the final noise wall locations.

This UDOT noise wall video explains our noise wall balloting process.

The design phase is anticipated to take about 18 months, from fall 2024 through early 2026. Construction is expected to last about two years from mid-2026 through 2028.

Project information was shared at the 2025 Dixie Regional Transportation Expo. The information boards are linked here.

live
live
Design 2024 - 2026

UDOT is developing final design plans for improvements to I-15 including:

  • Building an additional lane in each direction on I-15 between Bluff Street (Exit 6) and St. George Blvd (Exit 8)
  • Raise I-15 and replace structures at 100 S and 700 S
  • Raise I-15 and build new structures over 400 E and 900 S
  • Build new local roads to connect 400 E 900 S under I-15

Design began in fall 2024 and is expected to be completed in early 2026.

planned
planned
Construction 2026 - 2028

Construction is expected to begin in mid-2026 and continue through 2028.

complete
complete
Environmental Assessment 2022 - 2023

UDOT prepared an EA to determine the need for a new interchange on I-15 and 700 South, evaluate interchange alternatives, and identify environmental impacts. This EA started in April 2022 and was completed in October 2023.

UDOT is not expected to build the study's recommended single-point urban interchange (SPUI) at 700 South until a later phase due to fiscal constraints.