The Nevada Department of Transportation’s (NDOT) $40 million Interstate 515 Viaduct Rehabilitation Project is nearing completion. When complete, it will boost travel through downtown Las Vegas.

“Any viaduct or elevated freeway structure needs extra maintenance and care,” says Justin Hopkins, Public Information Officer for NDOT. “This project is about making sure that viaduct structure is safe and can live on into the future.”

The viaduct was built about 60 years ago and had not had major upgrades since then. The department added a couple of other components to the work to enhance safety in the area and bring the nearby bridges up to current standards.

About 158,000 vehicles per day travel on the southbound lanes, with a peak of 7,000 vehicles per hour, and 138,000 vehicles per day on the northbound lanes, with a peak of 5,100 per hour.

“This project runs close to downtown Las Vegas, so we have been mindful of stakeholders in the area,” says Hopkins, explaining that the department’s public outreach team has kept in contact with nearby residents, neighborhood groups, and businesses to keep everyone informed about closures. “Having good relationships with the stakeholders have been big benefits. The work was in older, established neighborhoods, and there were relatively few headaches.”

NDOT plans another phase farther to the east of the viaduct on I-515 at Charleston Boulevard to start this fall. It is designed to add capacity and improve traffic operations. The work will entail reconfiguring the interchange with wider ramps, widening and reconstructing Charleston Boulevard, adding one lane in each direction of I-515, creating dedicated left-turn lanes to eliminate bottlenecks, and adding LED lighting and pedestrian accessibility on the surface street. The work is expected to start this year and finish in 2024. Estimated cost is $59 million. Eventually, the department plans to replace the viaduct.

The I-515 Viaduct Rehab Project has three components:

• The rehabilitation of the I-515 (U.S. 95/93) viaduct – an elevated roadway – between the Union Pacific Railroad tracks and 21st Street to extend its near-term service life as identified as a need from the I-515 Alternatives Development Study
• The replacement of the Eastern Avenue and Desert Inn Road bridges, both with structurally deficient superstructures. The bridges’ structural steel box girders had developed fatigue cracks. Eastern Avenue is a major thoroughfare, as is Desert Inn Road about 3 miles east of the viaduct.
• The addition of a southbound auxiliary lane between the Spaghetti Bowl and Eastern Avenue

Hopkins indicates that by adding the auxiliary lane, it will give drivers more time to get in and out and reduce traffic backups and collisions.

Final design by NDOT began in January 2013 for the viaduct, in November 2017 for the auxiliary lane, and in October 2019 for the bridges. There were no environmental concerns or mitigations needed. No property acquisitions were required.

The viaduct cost $26 million and the bridge replacements $14 million.

Las Vegas Paving of Las Vegas, founded in 1958, received the contract to perform the construction activities and began work in June 2021. The department required the contractor to work Monday through Saturday and finish the project within 370 working days.

“We are ahead of schedule,” says Hopkins, explaining that the original goal was completion in the fall, but now it will likely finish this summer.

That means the contractor will likely earn early completion incentives. NDOT added incentives of $16,250 per day up to $1.38 million for early completion, disincentives of $16,250 per day and liquidated damages for late completion of $11,300 per day in addition to the disincentives.

The viaduct rehab entailed repairing and overlaying the 1.2 million-square-foot deck surface, reconstructing the Casino Center off ramp hinge, and seismically retrofitting selected pier columns.

“The seismic retrofitting of the viaduct consisted of excavating to the bottom of the columns, cleaning, then wrapping the columns with fiberglass and resin to create a composite wrap the full length of the column,” Hopkins explains. In the case of an earthquake, “this will keep the columns together.”

During construction, viaduct ramp closures were limited to one ramp at a time and with some lane closures while paving the deck. A couple of 24-hour full closures were needed on weekends for restriping.

Creating an additional southbound lane between Interstate 15 and Eastern Avenue required relocation of the existing median, restriping to make narrower lanes and shoulders, and widening the southbound off-ramp to two lanes – essentially eliminating part of the shoulder.

The bridge replacements involved demolishing the structures in phases, taking down the southern side first. Then crews rebuilt the southern side, shifted traffic to it and then replaced the northern side. During construction, I-515 was reduced to two lanes in each direction and down to one lane in each direction during overnight hours.

Utah Pacific Bridge and Steel based in Lindon, Utah, fabricated the steel girders for the Eastern and Desert Inn bridges. The project consumed 614,000 pounds of steel.

On the bridges, “all existing lighting was changed to LED luminaires including the bridge underdeck lighting,” Hopkins says. “There were no pedestrian improvements included with the new bridge construction.”

The entire job must be complete by December 2022, but as mentioned, the work is moving swiftly.

“One of the benefits is the speed with which we have been able to complete this project. Bringing this freeway elevated structure above and beyond is great,” Hopkins concludes. “This project came together well, and we are glad it is going to wrap up quickly.”