Oct. 19, 2007 The state of Pennsylvania has introduced a new regulation to limit the idling time of diesel-powered commercial vehicles to five minutes per hour, Environment News Service reports.

The regulation is aimed primarily at the drivers of big rigs, who must idle their engines to heat or cool their cabs during federally mandated rest breaks. The rule includes exemptions for extreme weather.

The U.S. EPA estimates that long-duration truck and locomotive engine idling consumes more than 1 billion gallons of diesel fuel and 11 million tons of carbon dioxide each year. In 2003, it set up the National Transportation Idle Free Corridors project to eliminate unnecessary truck and locomotive idling along major transportation corridors. (Here's an interactive map.)

A number of companies have developed truck idling technologies that enable automatic shutoff or allow drivers to connect to "shore power" at truck stops.

Pennsylvania's regulation, developed by the state Department of Environmental Protection, must be opened to public comment and discussed in a public hearing before final consideration by the Environmental Quality Board.

The state's extensive highway system includes 260 truck stops, 47 public rest areas, and more than 13,000 truck parking spaces.