Two express lanes will be added to both the northbound and southbound freeway. Unlike the high-occupancy vehicle lanes that recently opened on U.S. Highway 95, any vehicle, including those with only one occupant, will be permitted to use the express lanes.

"You will get on just north of I-215 if you are going north and just zip on through," said Jim Souba, assistant Transportation Department director of engineering.

The freeway currently has four lanes in each direction. The Transportation Department intends to construct a fifth lane in each direction by using the existing road shoulders. The two left lanes then will be converted into express lanes and will be segregated from the other lanes of the freeway.

"It is a good deal," state Transportation Director Susan Martinovich said. "There is room there for another lane, and we don't have to acquire right of way. That is a big savings."

A contract for the work, which officials said could end up costing as little as $25 million, will be awarded soon and the project will be completed in the summer of 2009.

Souba said traffic will move faster in the express lanes because motorists traveling in the lanes will be required to drive the entire 5.5-mile length before exiting, at either Sahara or Russell. Exceptions will be made for emergency vehicles.

Vehicles changing lanes to exit at the Spring Mountain Road, Tropicana Avenue and Flamingo Road interchanges cause traffic to slow, Souba said.

"All the brake lights come on and it takes a long time to pick up the flow," he said.

Studies have found that a large percentage of the 250,000 vehicles using I-15 each day travel the entire Russell-to-Sahara stretch.

What engineers call "candlesticks" -- foot-high, flexible plastic poles -- will be installed between the express lanes and the general freeway lanes.

The candlesticks will serve as a barrier to prevent vehicles from entering the express lanes, except at the Russell and Sahara, but will not damage vehicles that hit them.

The express lane project will be the first highway project completed with funds appropriated by the 2007 Legislature. Money for the express lanes comes from the $20 million a year in room taxes that the Las Vegas Convention and Visitors Authority must contribute to state highway improvements.

Legislators found enough money to cover a $1 billion highway construction program by taking existing room taxes, car rental fees and county property tax revenue.

Contact reporter Ed Vogel at evogel@reviewjournal.com or (775) 687-3901.