For Whom the Toll Bells Ring--and at 35 M.P.H., No Less

SAN FRANCISCO — State highway officials are experimenting with an automated toll system they say would allow motorists to cruise past the toll booths as fast as 35 m.p.h. and be billed by mail.

The California Department of Transportation says the $16,000, radio-controlled toll devices may be used on some bridges in the San Francisco Bay Area and elsewhere in the state as soon as early 1987.

Under the system, cars would be equipped with credit card-sized “surface acoustic wave tags” costing $20, and containing an antenna and a crystal chip the size of a dime. When the motorist passed through a toll booth, an “interrogator” machine in the booth would send out a radio signal to the car. The wave tag would emit a response unique to that car and driver.

Stored in a Computer

The information would be stored in a computer, and the bill would arrive at the end of the month.

Transportation department spokesman Gene Berthelsen said the system had a 95% accuracy rate in a four-month test last summer on the Coronado Bridge in San Diego. He said that figure will probably be improved by placing the tags differently for new tests scheduled to begin soon.

Agency officials said the Golden Gate Bridge would not get the automated devices. Berthelsen also cautioned that heavy congestion on the Bay Bridge linking Oakland and San Francisco would not be helped by the system, since it is the result of a merging of a large number of lanes, not the toll booths.