WASHINGTON A decade after antilock brake systems began showing up on over-the-road buses and trucks, the Commercial Vehicle Safety Alliance has issued new guidance for roadside inspectors to use when checking the systems.

The CVSA published a 10-page ABS Inspection Bulletin, containing the new guidance, in the wake of a study from the U.S. Department of Transportation that found that one in six trucks and buses manufactured in the past 10 years has a defective antilock braking system.

The USDOT study involved inspections of ABS indicator lamps on 1,000 vehicles. Roughly 17 percent of the vehicles had malfunctioning ABS indictor lamps. The results were much worse for the trailers pulled by truckers, where one in three had defective ABS.

These results, CVSA said in its bulletin, "point out the need for more intensive inspection of vehicle ABS."

The bulk of the CVSA bulletin is devoted to helping inspectors figure out which over-the-road vehicles manufactured since 1997 are required to have ABS, and the fairly simple inspection procedures to be used in checking whether the system is operating properly.

The bulletin also points out that, for inspectors, locating the ABS malfunction indicator lamp may be difficult on many vehicles because there are no regulations governing its location, shape, size, color or operation.

The location and style of dash-mounted ABS malfunction lamps, for example, vary widely between vehicle manufacturers and even among vehicles produced by any given manufacturer, CVSA noted.

And, in some cases, because of the lack of uniformity of the location and style of the indicator lights, "identifying the proper lamp can be challenging, particularly when the lamp is inoperative. In some cases, the lamp may turn on and off very quickly and may require several cycles to correctly identify the ABS malfunction lamp," the CVSA bulletin states.

Bottom line: Operators can expect bus safety inspectors to begin paying more attention to their coaches' antilock brake systems, meaning operators should, too.