A truck driver who apparently dozed off caused a fiery crash that closed part of Interstate 5 at Medford's south interchange for much of the day Monday.

A truck driver who apparently dozed off caused a fiery crash that closed part of Interstate 5 at Medford's south interchange for much of the day Monday.

A semitrailer towing two empty trailers failed to negotiate a slight curve taking traffic around construction at the interchange and slammed into a concrete barrier at about 5:35 a.m., Oregon State Police reported. The crash ripped open the truck's fuel tank and started a fire that destroyed the truck and deeply damaged the asphalt in the right southbound lane. Repairs to the pavement took most of the day and backed up traffic for miles.

Some witnesses told police of an explosion and fireball, OSP senior trooper Bill Matson said.

Medford Fire Department got an initial report of a small fire at the scene of a truck crash and sent one fire engine, Battalion Chief Brian Fish said. However, the first crew to arrive found a large, rapidly growing blaze and called for a second Medford engine and backup from Phoenix.

"Once the fuel tank opened up, there was a lot of fire and smoke," Fish said. "It started small and spread 30 or so feet so fast it made it look like a ball of flame."

Driver Doug McClimans, 62, of Vancouver, Wash., and passenger Oran Edwards, 59, of Fairview, escaped without life-threatening injuries, Matson said. Mercy Flights ambulances took both men to Rogue Valley Medical Center, where Edwards was reportedly in fair condition in intensive care Monday afternoon. McClimans wasn't listed on patient records.

Matson said McClimans told him that he thought he had fallen asleep before hitting the barrier. The driver could face a citation charging him with failure to maintain a lane of travel, but the investigation was still under way Monday.

The crash pushed the concrete barriers roughly 20 feet, said Gary Leaming, Oregon Department of Transportation spokesman. The fire roared through the 2005 Volvo tractor and the first box trailer after they hit the barriers, but the second trailer flipped onto its side away from the fire, Matson said. The trailers were empty because the truck was on its way from Portland to Sacramento to pick up freight for UPS, Matson said.

The Oregon Department of Transportation closed the southbound lanes of the freeway and rerouted traffic from the north Medford interchange at mile 30 through town on Highway 99 while police and fire crews dealt with the crash. Most traffic returned to the interstate at Phoenix, but weight restrictions on a bridge over Bear Creek forced some trucks to continue on Highway 99 to Talent, Leaming said.

Traffic was heavy through Medford during the morning commute, but no accidents related to the detour and the congestion it caused were reported, Medford police Lt. Tim Doney said. The city's public works department assisted law enforcement and transportation crews with posting detour signs.

The interstate's left southbound lane at the crash site reopened at about 9:45 a.m., enabling traffic to creep through the area.

Traffic backed up on the freeway throughout the day. During the worst delays in the morning, traffic was backed up more than three miles, ODOT Assistant District Manager Shawn Stephens reported.

Wildish Standard Paving of Eugene, general contractor on the $70 million interchange project, and LTM Inc., of Medford, assisted emergency responders and an environmental clean-up company to deal with the aftermath of the crash, Matson said. He praised the cooperation between numerous agencies and companies.

ODOT crews and the contractors ground away a stretch of damaged asphalt about 40 feet long and 8 inches deep in the right lane to reach asphalt that hadn't been affected by the extreme heat of the fuel fire, Leaming reported. Then, they rebuilt the road's surface with four 2-inch layers of asphalt. The repaving work was done and all lanes reopened at about 4:45 p.m.

"These types of incidents happen, and it just really messes everybody's schedule up," Leaming said.

He said he didn't know if ODOT could try to recover cleanup and repair costs, which weren't disclosed Monday.

Reach reporter Anita Burke at 776-4485 or aburke@mailtribune.com