The devices, called transponders, usually mount on a truck's windshield. They are required for automated toll payment and for services such as PrePass, which allow trucks with proper credentials to bypass weigh stations. Unfortunately, systems have been developed and deployed independently in recent years with very little compatibility from one system to the next.
Now the FHWA has officially announced its intention to require a standard for Dedicated Short-Range Communications (DSRC), the means by which transponders communicate with electronic readers at toll booths, weigh stations and ports of entry. Hopefully a standard DSRC will mean a transponder from any manufacturers will communicate with any highway reader, so one transponder on a truck will work wherever electronic verification and communication is necessary.
In its official notice, FHWA has asked for comments on when a rule should take effect, how to best achieve compliance and how to deal with expensive systems already in place, among other issues.
A standard for such devices is a major goal of the Intelligent Transportation Society of America and has been a government concern since Congress directed the Secretary of Transportation to promote such standards in 1991 legislation.