Under budget and ahead of schedule, Utah County's high-occupancy vehicle lanes will open Friday.

Fifteen new miles of lanes on Interstate 15 in Utah County will mean a total of 38 miles of contiguous carpool lanes from 600 North in Salt Lake City to University Parkway in Orem, said Geoff Dupaix, a spokesman for the Utah Department of Transportation, in a statement.

Construction began in June 2005 and with its completion Utah motorists have access to the longest stretch of continuous carpool lanes in the country, he said.

The project was originally anticipated to be completed in early July, said Dave Nazare of UDOT.

"As the contractor started looking at the project they determined they could finish by the first week of June and then as springtime weather warmed up and the rain stopped and the ground dried out they were able to really accelerate, and now they are saying they will be done by Friday morning," Nazare said.

The project was originally contracted to cost $43 million but has come in about $1 million under budget, he said. UDOT has asked the contractor to use that money to apply a slurry-seal coat of oil over the existing pavement for the length of the project.

"That will extend the life of the pavement and make the lane lines show up better," he said.

"The contractor on this project, Wadsworth Brothers, did a great job of delivering a high-quality project early to the driving public," he said.

Between now and August there will be sporadic nighttime lane closures on I-15 as crews work to repave the freeway between 800 North in Provo and 500 East in American Fork, where potholes have pocked the road, Dupaix said.

The slurry work also will cause nighttime road closures between 500 East in American Fork and the Point of the Mountain.

Thirteen overpass bridges in Utah County were expanded for the project, Dupaix said.

"Utah County residents can look forward to decreased congestion and faster commute times on I-15 with the new carpool lanes," said John Njord, UDOT executive director in a statement. "We encourage motorists to find a co-worker, neighbor or family member to carpool with during the peak travel times."

Drivers can anticipate even better commutes when the carpool lanes on I-15 are converted to express lanes in early September, Dupaix said. Drivers with more than one person in the car may use the express lanes for free, while 600 solo drivers will be able to pay a $50 monthly fee to use the lanes.

The express lanes will relieve congestion in general purpose lanes and increase overall traffic speed during rush hour by up to 10 mph without negatively impacting travel time in the carpool lanes, Dupaix said.

In Salt Lake County, carpool lanes are carrying twice as many people in half the number of vehicles during afternoon commutes, Dupaix said. Carpooling also saves commuters gas and car mileage as well as up to 20 minutes during heavy commutes.

Commuters can find a carpool by visiting www.udot.utah.gov and clicking on "Find a carpool." Vehicles with more than one passenger, buses, motorcycles and clean-fuel vehicles are eligible to drive in the carpool lanes.

Caleb Warnock can be reached at 443-3263 or cwarnock@heraldextra.com.

This story appeared in The Daily Herald on page A1.