News that the American Trucking Associations (ATA) has backed legislation that would allow truckers to use bigger, heavier rigs wouldn't ordinarily come as much surprise. Truckers have lobbied for years for permission to run longer combination vehicles, or LCVs, throughout the country.

But a mid-February announcement from the ATA's board of directors has raised a few eyebrows. The board's vote to back such legislation represents a reversal for the truck group, which had agreed to refrain from that kind of lobbying. In 2003, the ATA entered into a truce with the Association of American Railroads (AAR) in which the ATA agreed to stop pushing for higher limits if the AAR would stop lobbying to ban existing double and triple trailers from the roads. That agreement apparently expired with passage of last year's Safe, Accountable, Flexible, and Efficient Transportation Equity Act-a Legacy for Users (SAFTEA-LU).

Though the debate has sometimes been framed as a safety issue, its roots lie in freight industry economics. Many truckers want permission to use bigger vehicles nationwide so that they can haul bigger payloads. Railroads see bigger vehicles as a direct threat to their share of the nation's freight market.