ST. GEORGE — Cut off from the rest of the state by the Grand Canyon, most Arizonans have never driven on the state’s remote 29-mile-long segment of Interstate 15. Despite its isolated location in a sparsely populated area known as the Arizona Strip, the Arizona Department of Transportation is committed to maintaining this route, which is of vital economic interest to the country as a key corridor that links transportation hub cities, including Los Angeles, Las Vegas and Salt Lake City.
On Friday, April 20, the Arizona State Transportation Board continued those efforts by awarding an $11.6 million contract to start a repaving project from the Virgin River to the Utah state line – milepost 13 to 29. This comes after ADOT has invested more than $15 million over the last decade to keep this corridor up to standards.
When the Federal Highway Administration and Arizona completed the I-15 section in the extreme northwest corner of the state, it was considered one of the engineering marvels of the Interstate Highway System, but it came at a cost. While the southern portion of the I-15 route was built close to the alignment of old U.S. 91, the northern section, through the Virgin River Gorge, was built through rugged terrain that crisscrosses the Virgin River Canyon. When it was completed in 1973, the scenic Virgin River Gorge passage was the most expensive section of rural highway, per mile, in the country.
After nearly 40 years of extensive use, the four-lane divided highway needs to be restored to keep up with the steadily increasing traffic that moves goods and people on the transcontinental highway through California (beginning in San Diego), Nevada, Arizona, Utah, Idaho and Montana. More than 1.4 million commercial trucks and nearly 221 million vehicle miles (the equivalent of nearly 9,000 trips around the globe) travel annually on Arizona’s portion of the interstate.
While addressing pavement issues along I-15 through this project and by budgeting nearly $15 million to repave another 13-mile portion of I-15 that extends to the Nevada state line in 2015, ADOT acknowledges that the highway’s bridges remain the top concern. The bridges remain safe, but are in need of significant upgrades and replacement.
ADOT is currently conducting a study for rehabilitation of all eight of the I-15 Virgin River bridges, which were constructed in the late 1960s and early 1970s. The study will evaluate replacing aging bridge superstructures, which includes the deck and the girders that support the pavement surface driven on by motorists. Since the bridges are narrow by modern standards, ADOT will also look to improve safety by widening the bridges and adding shoulders, where possible.
Funding for the I-15 Virgin River bridge rehabilitation projects will be a challenge. Current estimates to make the necessary improvements could cost as much as $250 million, which is why Arizona initiated discussions in 2011 with the Federal Highway Administration, Nevada and Utah to raise awareness of the situation on I-15 and explore opportunities to identify a funding solution.
Arizona is open to a multi-state approach to pay for the necessary rehabilitation of I-15. The Federal Highway Administration, Nevada and Utah have all completed assessments of the I-15 bridges in Arizona and concur with ADOT’s conclusions about the significant bridge needs. Arizona also has joined Nevada and Utah in a multi-state effort to coordinate long-range planning and seek funding for the I-15 corridor.
ADOT’s responsibility to maintain the roadway in a state of good repair has led the agency to seek several funding opportunities to assist the state in developing a solution. The agency has submitted multiple federal discretionary grants, including a joint application last month with the Nevada DOT and Utah DOT for a Transportation Investment Generating Economic Recovery (TIGER IV) grant to rehabilitate one of the Virgin River bridges (bridge 6 at milepost 16) for a total project cost of $27 million.
If ADOT receives the necessary federal funding from these grant applications, construction could start as soon as next year and could be completed by 2015.