The Challenge

Las Vegas sits in a 600 square mile dense desert basin with only one outlet for stormwater to Lake Meade making it susceptible to flooding during heavy rain events common in the area. In addition, mountain ranges surround Las Vegas on all sides, so runoff also contributes to excessive flooding along I-15.

“Las Vegas is like a large bowl with rocky soils that will not absorb water so high runoff and flash floods are frequent. The mega box culverts create huge underwater conveyance channels to help address the problem,” said Steve Nilforoushan, Regional Engineer for Rinker Materials. “Our reinforced concrete mega box culverts are ideal for preventing potential flash flooding in the Las Vegas Valley because they can move massive volumes of stormwater necessary to channel stormwater off of streets and highways.”

The Project NEON stormwater management system includes approximately 7,189 linear feet of MRCB ranging from 12′ x 6′ to 22′ x 6′ and 47,580 linear feet of RCP from 18″ to 72″ covered with as much as 38 feet of fill. The maximum flow capacity for 20 x 8 MRCB is 1,450 cfs. Installed using traditional crane and push method, the process was complicated because 46 girders had to be set including the longest precast girders in the state, measuring 168 feet long. The decision to install precast concrete produced locally rather than using cast-in-place not only helped keep the project on schedule, but also assured all components were ASTM 1577 certified including the custom beveled fittings that made S-shaped curves in the design possible. The result is a system with a peak Q capacity of 92 cfs, which is much higher the older storm drain capacity of only around 26-30 cfs.

“There was no waiting for cast-in-place concrete to cure, and as soon as our precast culverts were in place, cranes and other equipment could operate from on top them if needed. This minimized traffic closures and kept the project moving.”

Project NEON expanded the High Occupancy Vehicle (HOV) network more than 20 miles, added new north-south surface street connections reduced congestion, and accommodated regional economic development by improving access into downtown Las Vegas and Symphony Park as well as the medical and arts districts. While Project Neon was expected to be completed in four years, the design-build approach enabled each phase to be completed early and the entire project was completed within three years, despite the complexity of building new roadway and bridge structures while maintaining traffic and reducing ramp closures. Besides reducing congestion and facilitating vehicle movement, Project Neon is also intended to improve air quality by creating less idle time and vehicle exhaust. The $1 billion project is expected to reduce travel delays by 28 percent, which will yield $110 million in annual savings through increased productivity.

“It’s been a tremendous improvement on moving traffic flows through the center core of our community,” said Cara Clarke, spokeswoman for the Las Vegas Metro Chamber of Commerce. “It’s the major freight route going through our communities. It’s also a big tourism route, as well as just the day-to-day business traffic.” Project NEON earned Roads & Bridges magazine Top Road Construction Project in 2019 and the American Concrete Pipe Association 2019 Project Achievement Award.