Project Name: 400 South & I-15 Pedestrian Underpass – St. George, Utah
Owner: St. George City / UDOT / Dixie State University
Contractor: American Civil Constructors
Engineering Firm: Horrocks Engineers (project design), SPECS Civil Solutions, Inc. (precast structural design)
Date: March – August 2019
Manufacturer: Geneva Pipe and Precast
Product Specifications: (size, material, etc.): 16′-0″ W x 10′-11″ H x 8′ lay length; 204 lineal feet of arched, three-sided, box culvert
Tons: 500 (approximately 40,000 lbs each)
Photo courtesy of Mountain States Concrete Pipe Association
Overview:
This pedestrian underpass under I-15 connects the Dixie State University campus to the student housing and buildings on the east side of the freeway. It included installation of 204 feet of arched three-sided precast 16′ x 11′ box culvert.
Photo courtesy of Google Earth
Narrative:
A joint venture between UDOT, Dixie State University, and the City of St. George, the pedestrian tunnel beneath Interstate 15 provides a car-free commuter route between the university, student housing, and the St. George business district. Geneva Pipe and Precast fabricated the reinforced concrete sections used to construct the 204 foot long underpass at 400 South.
Photo courtesy of Geneva Pipe and Precast
To accommodate traffic on the interstate above during construction, the contractor installed the concrete sections in two phases. During phase I the Southbound Lanes of I-15 were shifted, allowing excavation and installation in the first half of the tunnel. The contractor then backfilled and paved a new section over the top of this completed stretch.
Photo courtesy of Geneva Pipe and Precast
During phase II, Northbound traffic was shifted while the contractor excavated the second half of the tunnel. The final concrete sections were installed about a month after completion of the first phase of construction.
Photo courtesy of Geneva Pipe and Precast
Today, the tunnel provides better connectivity and a safe pedestrian passage for the 11,000 students of Dixie University, their faculty and staff, and the citizens of St. George. By promoting alternative means of transportation including walking, biking and scootering, the infrastructure helps alleviate traffic in the area. The University is pleased with the outcome of this project, deeming it the “Trailblazer Tunnel.”
Photo Courtesy of Mountain States Concrete Pipe Association
A unique aspect of this project is the mural on the west face of the underpass and wing walls. The University held a competition where local artists could submit a design for the mural. The winner was Dixie State University alumna Tiffany Dewitt (@livelongandletter). The mural incorporates many of the education opportunities offered at Dixie State University, and provides some life and color to the project.
Photo courtesy of Twitter.com
APWA Utah Chapter Virtual Project Tour – “Trailblazer Tunnel”
In May 2021, the Utah Chapter of APWA highlighted this project as a virtual project tour. The video below provides a walk through of the completed project, along with interviews with the design engineer, the manufacturer, and the contractor.
News Articles about the project: