NDOT I-15 Tropicana Interchange Design and Public Outreach

Located in the heart of Las Vegas’s Resort Corridor, the Tropicana Avenue Interchange along Interstate 15 (I-15) connects people to the city’s many entertainment options. According to the Nevada Department of Transportation (NDOT), over 60,000 vehicles pass through the interchange daily, and nearly 300,000 use it during holiday weekends.

To enhance safety and mobility, NDOT launched the I-15/Tropicana Avenue Interchange project, a $386 million, design-build initiative that improves traffic flow by adding elevated high-occupancy vehicle ramps and other operational upgrades. Serving as Kiewit Construction’s primary engineering subconsultant, we were brought on board to partner in the design of the new interchange, which included the following transportation improvements:

• Roadway upgrades and widenings
• Bridges and retaining walls
• Intelligent Transportation Systems, featuring Active Traffic Management signs and modernized traffic signal controls
• Enhanced pavement markings
• Improved drainage, sewer and water systems
• Wider, more accessible pedestrian walkways

Before the project was awarded, we proactively addressed concerns raised by key stakeholders about the previous design and how it could possibly limit access to their businesses and future development. Within a week, digital and traffic modeling tools helped us visualize the interchange and develop initial concepts. This rapid response facilitated productive dialogue and resolved the concerns, prompting state officials to award our team the contract.

We then focused on delivering a high-quality final design, developing layouts aimed at preserving a flyover off-ramp slated for removal. Although upgrades required removing some of the structure, approximately two-thirds of it was retained, protecting a significant infrastructure investment.

Drainage improvements were also prioritized, given the interchange’s vulnerability to stormwater runoff, particularly during rainy seasons. Excess stormwater runoff on high-traffic interchanges can reduce driver visibility and increase the risk of accidents and hydroplaning. To mitigate these issues, the team connected the existing system to a nearby waterway, enabling efficient water conveyance and reducing roadway accumulation. Additionally, directing runoff to a controlled outlet improves safety and sustainability by minimizing erosion and potential flooding.

To safely perform this work within a tight, busy corridor, open-cut and trenchless construction methods were used. Open-cut construction involves excavating a trench to install or upgrade drainage infrastructure. While effective, it can be disruptive in high-traffic zones. Trenchless methods, such as horizontal directional drilling or pipe jacking, enable underground installation with minimal surface disruption—ideal for preserving traffic flow and reducing construction-related impacts. By strategically deploying both methods, the team:

• Maintained traffic operations during construction, minimizing delays.
• Enhanced worker safety by reducing exposure to active traffic zones.
• Accelerated project delivery through efficient installation techniques.
• Limited impacts to surrounding infrastructure.

Besides designing resilient infrastructure to enhance safety, the environment and operational efficiency, keeping people moving was key. Therefore, we implemented a comprehensive public outreach strategy that kept the community informed and traffic flowing, even during busy events like the Super Bowl and a Formula 1 race. Our outreach program included a website featuring real-time construction updates, detour maps and project milestones. User-friendly mobile applications shared notifications, interactive maps and route recommendations tailored to existing traffic conditions. Finally, a hotline provided support for questions, concerns and feedback, especially helping those without digital access.

These coordinated efforts maintained traffic flow and reinforced our commitment to community-centered project delivery. By providing easy, immediate access to current information, drivers could plan ahead or adjust their routes in real time, helping them avoid delays and navigate alternate routes efficiently.

In all, our team dedicated nearly 100,000 hours into the project that was completed in September 2025, helping strengthen public trust, safety and mobility throughout Las Vegas for years to come.

Please note: All images associated with this profile were provided by the Nevada Department of Transportation.