A National Transportation Safety Board official says there's evidence that the tractor-trailer driver who crossed the median Friday on I-65 near Munfordville, Ky., tried to stop before hitting a van in a head-on collision
that killed the driver and 10 people in the van.

According to published reports, tread marks left by the tractor-trailer in the dirt of the media between the northbound and southbound lanes of I-65 turn into smooth tire tracks several feet before the site of the crash. Christopher Hart, vice chairman of the NTSB, said the shift from tread marks to smooth tire tracks could indicate the southbound rig's brakes were locked up in the seconds before the collision.

What caused trucker Kenneth Laymon to cross the median is unknown. Laymon, from Alabama, was a driver for Hester Inc., which runs 25 tractor-trailers. His sister, Lori Cook, told a Birmingham, Ala., television station that her brother was an experienced truck driver with 26 years of experience and was a former driver trainer.

The Bowling Green Daily News reports that the tractor-trailer traveled about 425 feet after departing the southbound lane, driving through the median, over a cable barrier, hitting the van van, striking a rock wall and bursting into flames.

The cable barrier was installed two years ago after a similar wreck involving a tractor-trailer, van and pickup truck killed five people on the same stretch of road, about 35 miles northeast of Bowling Green. Hart said the barrier was intended to stop only cars and box trucks from crossing the median, not a tractor-trailer.