Safety Improvements Take Many Forms as Granite Construction Widens US 50 Near Silver Springs
Striving for Safer Travel: In the Midst of U.S. 50 Road Work, Granite Construction Mitigates Unexpected Flooding to Protect Local Community
For the $55 million widening of 10 miles of U.S. 50 near Silver Springs, Nevada, safety comes in many forms.
In the construction of the project, a four-lane, divided highway will replace two lanes prone to collisions. Ten high-T intersections will reduce conflict points between vehicles. At the junction of U.S. 50 and U.S. 95A, a roundabout that can efficiently handle increased traffic will eliminate a four-way stop. New fencing will keep wildlife from deadly interactions with cars.
In addition to those structural changes, General Contractor Granite Construction Company, based in Watsonville, California, put their crews and equipment to work during extensive snowmelt last Valentine’s Day to not only keep damaging floods off the roadway, but away from nearby homes, a hospital, and the airport.
Achieving Safer Travel
Financed with federal and state funds, the work between Roy’s Road and U.S. 95A is the second phase of widening U.S. 50 in Lyon County, Nevada.
“We’ve experienced a lot of accidents because of the two-lane roadway,” said Samantha Dowd, PE, Project Manager for the Nevada Department of Transportation (NDOT). “Drivers take risks with passing, which leads to head-on collisions and side swipes. By dividing the highway, we’ll reduce crashes.”
The corridor’s three-leg, high-T intersections will also increase safety and add mobility at county road crossings. “The high-T intersections allow traffic to enter and leave the interstate safely and gain speed with mainline traffic, rather than crossing additional lanes while attempting to accelerate,” Dowd explained. “They eliminate conflict points, while allowing us to place local traffic on eight new frontage roads and get them off the mainline. We like to use high-T intersections on projects throughout Nevada to give traffic a sort of refuge to merge into live, high-speed traffic.”
On both sides of the roadway, crews are installing 4-foot-tall steel posts connected by four-strand wire fencing. In addition, “All the openings will have cattle guards, so we’re controlling the entire corridor to prevent wildlife from entering,” Dowd said.
The project also extends the U.S. 95A northbound truck climbing lane and connects to the existing USA Parkway roundabout.
NDOT completed design in fall 2018 and Granite began construction last January. Traffic stayed on the existing lanes as crews built the new westbound lanes and north frontage roads. In mid-summer, traffic switched to the new lanes so workers could tear up the old pavement and reconstruct the new alignment’s eastbound lanes and south frontage roads. Granite Construction expects to finish the project by fall 2020.
Stopping the Flooding
In addition to all the safety features, the project includes significant drainage improvements. “U.S. 50 has had a hard time with flooding because the pipes that were installed when the roadway was built weren’t designed to carry the amount of flow we get now,” Dowd said. “In the design for this project, we increased the capacity of all the hydraulic structures so they can carry twice as much flow if a flooding event occurs.”
Before all the new structures could be installed, however, heavy snowfall in the mountains and an extended rain period last February led to extensive runoff in a short amount of time.
“When the flooding occurred, Granite Construction’s crew was very responsive and very helpful to the whole area,” Dowd said. “They took care of it in a very prompt manner so there was hardly any effect on people or the roadway system.”
Granite Construction’s efforts went beyond protecting their own work. “They were out there with their equipment moving dirt to create berms that redirected the water into the path it was supposed to go, instead of washing out homes,” Dowd said. “There’s a hospital that could’ve been affected, and they mitigated that before the water got to the facility. They also helped out with the airport, as well as with basic roadway functions. They were able to keep it open and alleviate all that flow.”
Within the project boundaries, crews made sure that flooding event wouldn’t lead to any future problems. “The flooding filled one of the concrete boxes that carries water under the existing highway, leaving behind sediment,” explained Marty Powers, Granite Construction’s Project Manager. “To prepare for potential future flooding issues, we cleaned out the box so water could travel under the highway without impediment.”
Efficiency in Detours and Materials
As Granite Construction prepared for their work, “One of the big challenges was coming up with a detour plan to construct the single-lane roundabout at the junction of U.S. 50 and U.S. 95A,” Powers said. “We’re going to utilize the permanent frontage roads around that intersection. We’ll detour all the traffic onto the frontage roads in a one-way, counterclockwise travel configuration to mimic the roundabout’s traffic pattern while we construct it in the internal area.”
The permanent frontage roads covered three of the quadrants around the roundabout. In the southwest quadrant, Granite will build a temporary road, then remove it at the end of the project.
NDOT designed the roundabout with concrete. “It helps with the haul trucks that come from across the state,” Dowd said. “The concrete helps with down braking and the weight of the trucks so we won’t need to repair it as often.”
The rest of the roadway consists of asphalt paving materials. For the aggregate base, “We brought in a portable crusher to an NDOT pit within the project limits,” Powers said. “During our bid process, we researched pits in the area. Granite had used another nearby pit in the past, but the state’s pit was closer and the material was a little better, so we worked with NDOT and change-ordered this pit into the project.”
To save time and recycle, “We plan to use asphalt millings from the existing highway in the bottom half of the 8-inch base section for the eastbound lanes,” Powers said. “We’ll haul the remaining grindings back to our hot plant to use as recycled asphalt product within the new hot mix.”
This project will complete the widening of U.S. 50 between Dayton Valley, Nevada, and U.S. 95A, increasing capacity to meet current and projected demands. Granite Construction wrapped up the first six-mile phase in 2015. Similar to phase 2, the first project expanded the two-lane highway to four divided lanes with frontage roads, high-T intersections, improved drainage structures, fencing, and cattle guards to increase safety. That project also included a wildlife undercrossing to allow horses and other animals to travel under U.S. 50 out of harm’s way.