Radar is limited to about 50 feet and can detect up to 32 objects, but it can't determine their size. Future systems will combine radar with lane departure warning system cameras and use image processing to better determine the size and location of objects in the road and what actions should be taken, says T.J. Thomas, product manager for driver assist systems at Bendix Commercial Vehicle Systems. Series production in commercial vehicles is still "a few years away," according to Thomas.

Then there's the matter of cost. The systems will have to show a payback in accident cost avoidance before the industry will adopt them, says Jim Tipka, director of public affairs at the American Trucking Associations. Extra costs are weighted against the business's tolerance for risk.

Traditionally, many trucking companies have opted to accept the risk of accidents rather than spend money on high-tech safety systems, but the costs of major accidents, when they do happen, hits the bottom line hard. Avondale Partners' Broughton says most of the major carriers have had a quarter that "got blown up" because of an accident.

Tire pressure monitoring

Tire pressure monitoring improves safety, but the bigger value lies in savings from improved fuel efficiency and extended tire life. The systems continuously monitor tire pressure; some automatically inflate tires as well. Properly inflated tires improve gas mileage, and at prices as high as US$400 per tire, keeping rubber on the road is one of the biggest maintenance costs for carriers.

J.B. Hunt buys 170,000 tires annually and has 500,000 tires on the fleet at any given time. Last year, a survey of the fleet showed that about 22 per cent of those tires were underinflated. It's hard to get drivers to check all 18 tires, especially in bad weather. "We have a really big interest in that," says Schimelpfenig.

The cost to add monitoring is about US$1,200 per 18-wheel truck, says Chris Nau, a sales representative for Doran Manufacturing, which makes tire pressure monitoring devices. He says savings from improved fuel mileage and longer tire life deliver a payback in about one year.

But Schneider's Damman says that for a carrier with a good tire-management program, the payback period for the technology is much longer. Schneider runs thousands of tires on 40,000 trailers and 10,000 tractors. That's 180,000 tires on the road at any given time. "We find that better than 96 per cent of them are at the recommended pressure," he says. Spending $US1,200 per tractor-trailer to benefit 4 per cent of the fleet just doesn't add up.

"We haven't found any case yet where we can rationalize the cost based on our metrics," says Damman. But carriers that don't see their trailers often enough to be able to maintain the tires the way they would like to might find a monitoring system to be effective. "It's going to be a different equation for everyone," he says.

The systems do have drawbacks. The sensors are mounted to each tire or valve stem. Since many tires are changed on the road, making sure that the monitoring system stays with the tractor and that the new tire has the same sensor on it can be a problem.

The systems also add another information display to an already crowded cab and haven't been integrated to work with onboard computers or to provide data to fleet management systems.