Even when drivers want to comply with the regulations, there's the risk that the driver will lose track of the exact hours worked in a given day. "If you're not keeping up with stuff in real time, you can put something in [the log] wrong. If you're off by 15 minutes, that's considered a falsified log, according to the DOT. That's one of the biggest nuisances," says Palmer. Many drivers like EOBRs because it makes tracking hours of service easier, she says.

Ultimately, the adoption of EOBRs may not come down to a cost/benefit analysis: The US Federal Motor Carrier Safety Administration is gradually moving toward making them mandatory for safety reasons.

Safety systems

The latest safety systems have evolved to the point where they can not only alert drivers, but also intervene in emergency situations. The payback from installing these systems is measured in reduced costs associated with accidents, including liability and lost revenues from out-of-service vehicles. Because tractor-trailers are so large, accidents often cause major property damage and loss of life. In 2006, large trucks were involved in 4,995 fatal accidents.

Most safety-monitoring systems warn the driver of an impending collision or rollover. But not all are designed to work with one another in an integrated way, and they don't all capture and support the transmission of safety event data to the dispatch center.

Vehicle stability systems

Of the active safety systems described here, vehicle stability, or anti-rollover, systems are the most mature and most widely adopted. The systems use two frame-mounted accelerometers to measure pitch (which can cause a rollover) and yaw (the propensity to slide, causing the rig to "jackknife") as a vehicle goes around a curve.

Such systems can alert the driver and mitigate an impending rollover by applying the vehicle braking systems and cutting fuel to the engine. Before taking action, the system takes into account factors such as how the driver is steering the vehicle, to gauge the driver's intent.

When activated, most systems make the event data available on the J1939 bus, where fleet management systems can pick it up and transmit an alert to the carrier's dispatch center in real time. J.B. Hunt has already adopted the technology. "We went right to the mitigation systems, and it did help reduce rollovers," Palmer says.

Schneider National has also adopted the systems. "The technology has come down to a price that made it realistic for us to put it in all of our trucks," Damman says, adding that the carrier has seen an improvement in fleet safety.

Forward collision warning and adaptive cruise control systems

These systems use forward-mounted radar to detect vehicles or other objects in the road ahead and warn the driver of an impending collision. Adaptive cruise control uses radar to maintain a safe following distance behind vehicles. Some systems issue collision warnings, while others can take actions to slow down the vehicle to avoid a crash.

Schneider's Damman isn't sure the warnings are effective in the long run. Initially, a driver's performance improves when using such systems, but after about six months, he typically goes back to his bad habits. "He thinks he's better than the system," says Damman.

But Damman sees potential in collision mitigation systems. "We're testing them, and we like them," he says.