In a message dated 9/20/02 5:50:47 PM Mountain Daylight Time, [log in to unmask] writes:

It is a network of fixed loops placed over Culways and such places for more
accurate readings. It records heavy vehicles, their configuration, axle
weights, speeds etc.

Many states are also installing these units. They are generally not used for enforcement purposes -- and in fact, it would be counterproductive to do so because there have been cases of major vandalism (by truckers?). They are used for "Weigh in Motion" studies for pavement and bridge design purposes. WIM sites are pretty accessible on the internet.

Best regards,
Steve Mueller