An area east of the Strip on the outskirts of downtown Las Vegas has had multiple traffic-related issues. In this area, I-515 takes a big curve to the west, known as the Charleston Curve. The Charleston Curve has been notorious for high levels of traffic and a high number of accidents. To remedy the situation, the Nevada Department of Transportation (NDOT) is working on the I-515/Charleston Interchange Project.

The project was inspired by studies that were undertaken by the City of Las Vegas. The goal was to improve Charleston Boulevard, which runs perpendicular and underneath I-515. NDOT conducted the studies because they were seeking to implement safety and operational enhancements along the I-515 corridor spanning from Eastern Avenue to Wyoming Avenue.

NDOT reported that there were 593 crashes over five years along this section of I-515. Even more crashes (920) occurred at the connection with Charleston Boulevard during the same five-year period. How do these numbers compare to other areas around the state? According to NDOT, total injury and property damage-only crash rates are four times higher than statewide averages.

NDOT has other objectives for the project. They include:

• Reducing travel delays
• Improving pedestrian and bicycle mobility
• Alleviating weaving moments

“This stretch of the freeway is one of the oldest in the system, and we’ve had to do many upgrades in the area,” said Justin Hopkins, a Public Information Officer for NDOT. “We need more driving lanes in the area to improve traffic operations [backups happen regularly during rush hour] and to improve mobility for pedestrians.”

According to NDOT, air quality becomes unhealthy when traffic backs up in the Las Vegas basin. In 2022, the annual average daily traffic (AADT) on Charleston Boulevard was 76,500 and 133,000 on I-515. NDOT projects the 2040 AADT will reach 83,000 on Charleston Boulevard east of the interchange and 37,000 on Charleston Boulevard west of the interchange.

The project includes a wide scope to accomplish NDOT’s goals. The scope includes the following:

• Widen and reconstruct Charleston Boulevard from Honolulu Street to Sacramento Drive
• Increase the number and length of turn lanes from Charleston Boulevard to I-515 ramps
• Upgrade sidewalks to Public Right-of-Way Accessibility Guideline standards
• Construct new traffic signals at ramp terminals and adjacent local road intersections
• Install new LED street lighting on Charleston Boulevard and high mast lighting on I-515
• Provide new landscape and aesthetic treatments
• Add one auxiliary lane in each direction on I-515 from Charleston Boulevard to Eastern Avenue
• Widen I-515/Charleston Boulevard interchange ramps
• Widen I-515/Eastern Avenue interchange northbound off-ramp
• Reconstruct existing sound wall along northbound I-515
• Add new sound wall on Charleston Boulevard

The project area is .5 miles on Charleston Boulevard and three miles on I-515.

“The main gist of the project is the widening of the three-mile stretch of I-515,” said Pablo Chavarria, a Project Manager with Granite Construction. The Watsonville, California-based company is serving as the general contractor for the project. “We demoed and widened the freeway 24 feet on the northbound side.”

The team demoed the northbound side even though an auxiliary lane is being added on both the northbound and southbound sides. In the busy urban area, the southbound side is too close to residents.

“To do 24 feet at one time rather than 12 on each side is more cost effective and avoids the right of way issues on the southbound side,” said Tony Colagiovanni, an Assistant Resident Engineer for Stantec. The Edmonton-based firm is supporting NDOT during the construction management of the project.

Because the project is in a well-populated area, the team installed many sound walls. The sound walls mitigate the impact on area residents and businesses.

The project also focuses on neighborhood aesthetics. “We crafted multiple pieces of art designed to fit the neighborhood,” Hopkins said. “We’re also repairing landscaping and adding new LED lights.”

Construction in dense urban areas such as this one, which includes businesses and residences, can be challenging. “We’ve put lots of thought into traffic control and how we can keep pedestrians along the busy Charleston Boulevard area safe,” Chavarria said. “We’ve partnered with NDOT to accelerate the project where we can. To lessen impact, we’ve added working hours wherever possible.”

The bridge foundations have also presented a challenge — underground water. The team has utilized slurry and temporary casing techniques prior to pouring concrete in the drilled shaft. There are also wet conditions on the ramps, resulting in subgrade remediation on Charleston Boulevard.

Colagiovanni said that working on an existing freeway is always more difficult than building something from scratch. One of the issues that makes it more challenging is ensuring elevations are spot on. “This project had many utility conflicts,” he said. “It’s always a good day when you’re out of the ground and building up.”

To make this project work and meet public expectations, the team conducted significant public outreach. Because the area has a large contingent of Spanish speakers, all materials (whether hard copy or online) are bilingual.

“We’ve also worked closely with traditional media interests such as newspapers and media to keep the public informed about the heavily traveled roadways,” Hopkins said.

Stantec works with NDOT regularly, but this project marks the first time Stantec has worked with Granite. NDOT and Granite have worked together in the past, however it has been a while since the two teamed up.

“From our perspective, this has been a fun project because there are so many different types of construction, and it includes a little bit of everything,” Chavaria said. “We’re motivated to reestablish a relationship with NDOT.”

Granite, according to Chavaria, has bought into NDOT’s philosophy. The philosophy here includes regular weekly meetings. “The weekly meetings have fostered open and honest partnering,” Hopkins said. “Granite has been doing a great job managing subs and construction and working on things proactively.”

This project is being delivered via the construction manager at risk (CMAR) method. When employing this method, the owner contracts a construction manager to handle a project during the design phase and to oversee it until project completion. Granite was selected during preconstruction in 2017. “I think NDOT chose [the] CMAR method to get a handle on the risks and control the costs,” Chavaria said.

The $75 million project is on schedule and on budget. The federal government is providing 95 percent of the financing, and the state of Nevada is paying the remaining 5 percent.

Construction on the project began in August 2022, and it is scheduled to be completed in July 2024 or after 460 working days.

When the I-515/Charleston Interchange Project is completed, the area will be set up to change its reputation for high amounts of traffic and accidents. There will be improved pedestrian access and increased reliability. NDOT expects the auxiliary lanes to reduce weaving and make the area safer.

• Owner: Nevada Department of Transportation
• General Contractor: Granite Construction, Inc., Watsonville, California; Pablo Chavarria, Project Manager
• Construction Manager: AECOM/Stantec augmenting NDOT Crew 915: Susan Doucet, NDOT Assistant Resident Engineer; Tony Colagiovanni, Stantec Assistant Resident Engineer
• Designer: CA Group, Las Vegas, Nevada