The company was granted a temporary exemption in 1998, since significant alterations were needed before its dump body trailers could comply.
Since then Beall has come up with a number of potential designs, including an articulated design, but the devices either interfere with paving equipment or have maintenance problems.
In its petition for a three-year extension the company said it continues to test hinged, retractable devices but it hasn't solved clearance issues associated with pavers. One solution, raising the box, also raises the center of gravity and reduces the stability of the trailers. Asphalt service, over a period of time, will "render such devices unusable," the company said. Moreover, it's possible to operate a trailer with the rear guard in the retractable position, thus the design doesn't comply with federal rules.
Beall said that if the extension isn't granted it would lose a product that accounts for 40% of its production.
For more information see the January 20, 2000, Federal Register available on the Internet at www.nara.gov/fedreg.