Cave Rock tunnel at Lake Tahoe to be extended 60 feet this summer

The westbound, lakeside Cave Rock tunnel entrance will get a makeover this summer, one that will stop rocks from falling onto Highway 50, add lighting to the inside of the tunnel as well as adding water quality improvements.

Devin Cartwright, Supervisor with the Nevada Department of Transportation's Roadway Design Division, spoke to the South Lake Tahoe Lodging Association Thursday, giving them a overview of the project that will bring with it one lane of traffic in each direction, causing some traffic delays, 24-hours-a-day, 7-days-a-week from May to October, 2016.

Rocks, some as big as four-feet by four-feet have been falling from the hill, most recently as last week when lanes were closed as a bulldozer removed them from the roadway. Last year temporary steel netting was placed on the hillside, but it wasn't meant as a long-term solution.

The Cave Rock tunnel will get a new 60-foot long and 27-foot tall structure added to the entrance that will extend the existing tunnel to enhance safety by catching rock fall before it reaches the roadway.

The tunnel extension will replicate natural colors, patterns and textures to match the existing rock face. Lighting and white paint will be added inside each tunnel for better visibility and two new overhead signs will be installed to automatically notify drivers of bicyclists or potentially icy conditions in the tunnels. Westbound U.S. 50 lanes and the roadway median between Cave Rock and the Cave Rock State Park boat launch entrance will also be paved.
The new overhead signs that will replace the current yellow flashing ones which notify drivers when bicyclists are in the tunnel as well as icy conditions. Cyclists will now be detected by radar, causing the sign to light up with a "Bike in tunnel" message. Icy conditions will also cause the sign to light up. At times these conditions are not in place, the sign will remain dark.

NDOT worked with the Washoe Indians on the project as Cave Rock is a sacred monument of their culture. The other two options they had to fix the problem of falling rocks were either more intrusive or wouldn't solve the problem adequately. One of the choices required scaling back all rocks on top of the tunnel.

Taking advantage of the lane closures, NDOT will install water quality improvements such as enhanced roadside drainage inlets and sediment filtration systems along U.S. 50 from approximately one mile and four miles north of Cave Rock.

During construction, traffic will be reduced to one lane in each direction through the eastbound Cave Rock tunnel, with reduced speed limits and some limited travel delays to be expected. Traffic north of Cave Rock will be reduced to one lane in the eastbound direction with short term westbound one-lane closures.

There are nine biking and running events in Lake Tahoe during the summer that use Highway 50 through the tunnel, and NDOT has plans in place. During those times, flaggers will be in place and traffic flow will be reduced to only one lane while the race participants use the other lane. Flaggers will also be at the tunnel during heavy traffic periods.

Cartwright said the reduction of four lanes down to two will start a mile before the tunnel to ensure vehicles slow down. "We will have lane shifting to make you feeling uncomfortable," said Cartwright. "This is so people will slow down." In addition, four lanes will reduce to two a mile before actually needed to keep speeds down.
NDOT could put up a message board near Kingsbury Grade (SR267) to divert traffic heading to the valley should the area near Cave Rock get too congested.

Plans are also in place for emergency vehicles. Should they to get through, the construction zone inside the lakeside tunnel has a pass-through built into it, one that is big enough for a fire engine.

The contractor on the tunnel project will get a $300,000 bonus if the tunnel is completed in 100 working days instead of the allotted 120 working days. A total of $5 million is being spent in that area this summer, $2.4 million on the tunnel, and $2.6 million on water quality.

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