WASHINGTON, D.C. — Citing distraction from the use of a mobile phone by the driver of an 18-wheel semi-truck as the probable cause of a crash that killed 11 people, the National Transportation Safety Board (NTSB) recommended banning the use of mobile phones by commercial drivers, except in emergencies.

"Distracted driving is becoming increasingly prevalent, exacerbating the danger we encounter daily on our roadways," NTSB Chairman Deborah Hersman said. "It can be especially lethal when the distracted driver is at the wheel of a vehicle that weighs 40 tons and travels at highway speeds."

Around 5:14 a.m. on March 26, 2010, near Munfordville, Ky., a truck-tractor semi-trailer combination unit driven by a 45-year-old man departed the left lane of southbound Interstate 65, crossed a 60-foot-wide median, struck and overrode a cable barrier system, entered the northbound travel lanes, and struck a 15-passenger van.

The van was driven by a 41-year-old man and occupied by 11 passengers (eight adults, two small children and an infant). The truck driver and 10 of the 12 van occupants were killed.

Investigators determined that the driver used his mobile phone for calls and text messages a total of 69 times while driving in the 24-hour period prior to the accident. The driver made four calls in the minutes leading up to the crash, making the last call at 5:14 a.m., coinciding with the time that the truck departed the highway.

NTSB also determined that the median barrier system, which had recently been installed following another cross-median fatal accident on the same section of I-65, contributed to the severity of the accident because it was not designed to redirect or contain a vehicle of the accident truck's size. The safety board said that because median crossover accidents involving large vehicles are so deadly, it made recommendations regarding the use of appropriately designed median barriers on roadways with high volumes of commercial vehicles.

At a meeting on Tuesday, the NTSB issued 15 new safety recommendations to the Federal Highway Administration, the Federal Motor Carrier Safety Administration (FMCSA), the National Highway Traffic Safety Administration, the American Association of State Highway and Transportation Officials, the Governors Highway Safety Association, all 50 states and the District of Columbia. The board also reiterated two previously issued recommendations to the FMCSA.

One new recommendation to the FMCSA is to “prohibit the use of both handheld and hands-free cellular telephones by all CDL holders while driving in commercial operations, except in emergencies.” This supersedes the similar NTSB Safety Recommendation H-06-27.

A synopsis of the NTSB report on the Kentucky crash, including the probable cause, findings and a complete list of all of the safety recommendations, is available on the NTSB website. The board said on Tuesday that its full report would be available on the website in several weeks.