Granite Construction and Nevada DOT Enhance Mobility on Scenic SR 28
A Safer State Route 28: New Shared-Use Path to Improve Access Near Lake Tahoe
Pedestrians, bicyclists and drivers will be able to more safely enjoy the pristine and scenic east shore of Lake Tahoe, when the Nevada Department of Transportation (NDOT) finishes the $36 million State Route 28 Shared-Use Path, Water Quality, and Safety Improvement project.
“The east shore is a heavily trafficked area with popular beaches and beautiful scenery,” says Jenn Boyd, Weidinger Public Relations, Spokesperson for the project. “This path enhances traffic safety and mobility on SR 28 and is a way to access Sand Harbor and provide alternative transit modes to recreation and trails.”
More than 2.6 million vehicles, annually, travel on SR 28, a two-lane designated Scenic Byway. Nearly 2,000 pedestrians and bicyclists share the road and its narrow shoulders.
The 3-mile shared-use path, from the south end of Incline Village to Sand Harbor, a beach area, will provide a safer place for them to walk and bike. The project also includes the construction of 16 vista points, scenic overlook areas and places to pull off the road in an emergency, and three parking areas that will allow motorists to park in a safe place and not on the side of the road. The path will feature benches and resting places to “soak up the view,” Boyd says.
The project includes drainage structures, storm drain pipe, curb and gutter, rip rap and fiberoptic conduit to help preserve the clarity of the lake and keep the area connected.
The shared-use path received federal, state and local funding and $750,000 in private donations to the Tahoe Fund.
The path will be near to the road, but above it or below it, depending on the section. At one point, it crosses from the mountain side of the road to the lake side via a concrete box culvert tunnel.
Granite Construction of Watsonville, California, serves as the construction manager at risk. Crews work 24 hours a day, five days a week, with weekends off, due to the tourist traffic. Due to Tahoe Regional Planning Agency grading season requirements, the company can only work from May 1 until October 15.
“This is a safety project and a water quality-improvement project,” says Cody Cummings, Project Manager for Granite. “It’s pretty dangerous. People park anywhere they can fit a car. It’s narrow, and they walk along the guardrail.”
“The location would be the No. 1 challenge,” Cummings says. “This part of the lakeshore is among the most untouched.”
Limited access, environmental concerns and a difficult terrain present additional challenges.
Prep work for the project began in 2016. Granite built two parking lots and a tunnel under SR 28 for the path. Crews built a temporary shoofly to allow SR 28 to remain open during construction, then excavated under SR 28, installed precast concrete structures, backfilled and paved. The 14-foot-wide and 10-foot-tall concrete boxes weighed 25 tons each. Granite completed one side of the road, diverted traffic to it and then started work on the other side. Crews worked 24 hours per day for 11 days to complete it.
“Basically, we put a giant box culvert under the highway, so pedestrian traffic is kept off the road,” Cummings says.
As part of that work, Granite relocated a 16-inch, high-pressure sewer main before putting the tunnel in.
Granite and its subcontractors have been innovative in creating access from the roadway and limiting traffic delays while getting the foundations in, Cummings says. Sometimes, crews have worked on an aspect of the project from two different angles, meeting in the middle.
“We have used a lot of specialized equipment,” adds John O’Day, a Project Manager with Granite.
Granite used a spider excavator on the project. It has four legs, like outriggers, to articulate over difficult terrains, such as steep slopes and boulders. The company also has used small off-road haul trucks, which can turn around in tight spaces without getting stuck. The drilling equipment for the bridges was modified so it could reach over the guard rail to get to the slopes.
“It was more efficient with the drilling,” O’Day says.
The project has required construction of eight sculpted shotcrete, soil nail walls.
“To make the width of the path, we had to put soil nail walls up to help support the roadway,” Cummings said. “A soil nail is a grouted anchor in the slope. Then we place wired mesh and apply shotcrete.”
The team has sculpted the surface to give the appearance of rocks to blend into the natural environment. Soil conditions have varied from sandy to boulders and solid rock.
In 2017, Granite completed about 1.5 miles of the shared path. The company also added storm drains, curb and gutter, and an intelligent information system.
This year, Granite is building six short-span pedestrian bridges, ranging from 32 feet to 765 feet in length. Five of them have micropile foundations ranging in size from 5.5 inches to 10 inches in diameter and up to 40 feet in depth. The sixth one has drilled shafts with a rebar cage and poured concrete. All together, the lengths of the six bridges total 1,200 linear feet. The bridges have a fiber-reinforced decking, which were fabricated by Composite Advantage of Dayton, Ohio. The pieces are fabricated in 45-foot to 50-foot sections, with steel stringers attached prior to shipping to the project for installation.
The road will remain open during the project, with one-lane, flagged controlled closures. The department has notified motorists to expect 20-minute to 30-minute delays. Granite and the department have developed a plan to minimize delays, especially during the popular summer months, which also are the prime construction months.
The path will provide environmental benefits, by getting more cars off the road and people on the trails, Boyd says.
Half of the parking areas will have 10-foot-wide permeable pavers. The other half is asphalt, which has been graded to drain toward the permeable pavers.
Granite installed an Environmental Passive Integrated Chamber (EPIC) Curb Cut stormwater transfer filter system that uses gravity to capture and clean the water. The system separates water, oils, sand and sediment and uses an anaerobic treatment before releasing the treated water into the existing storm-drain pipes.
The EPIC system has a rubber liner with a black corrugated pipe, flat on one side, Cummings explains. The pipes are connected to each chamber allowing the water to filter out sediment and other contaminants before it enters the storm drain system and eventually heads to the lake.
“When you get storms and rainwater, it permeates through the pavers and rock into the chambers and it helps to settle out the sediment,” Cummings says. “It fills up and moves from one chamber to the next until it connects to a drainage inlet.”
Due to the path’s location near the lake, NDOT and Granite have taken every precaution to ensure runoff or construction activity does not pollute the lake. If it rains or snows, crews will stop work to try to ensure sediment does not enter the storm drain system or Lake Tahoe.
“In most places, we are using traditional methods, wire-back silt fence, but in some places that are rocky, we have been innovative,” Cummings says. “We have drilled into the rock and installed threaded rebar with rock fall fencing and attached the silt fence to that.”
When the project finishes up either this fall or next spring, visitors to the area will have safer access to the lake and hiking trails through the rocky and scenic terrain.
“The biggest challenge and also the most exciting part is being able to conquer the difficult access and get this share-use path built,” Cummings says. “We are getting through it. It’s one rock at a time.”