An automated toll-payment experiment on the Golden Gate Bridge improves traffic flow.

In 1969, the U.S. Department of Transportation implemented an experiment in San Francisco, allowing commuter buses to pay their Golden Gate Bridge tolls using an automated system. According to an article in Computerworld magazine, the experiment aimed to reduce traffic bottlenecks caused by toll booths and reduce the inconvenience to drivers. First conceived in 1959, the idea behind this system would later become the widespread electronic toll collection systems that exist all across the United States today. Among the most well-known is the “EZ pass” system accepted across 17 states.

The “Automatic Vehicle Identification” system was powered by an IBM 1800 computer capable of monitoring passing vehicles equipped with a crystal-controlled transponder. When activated by a signal from a radio transmitter installed in the bridge pavement, the transponder generated a code signal at a set frequency. This code was received by a second antenna, passed to the IBM 1800 computer, and then used to identify the vehicle.

Only official bridge authority vehicles were equipped with transponders and used for the experiment. An engineer on the project told Computerworld that while the system was “entirely experimental,” if the experiment was successful “we can work towards making this system available to other commercial vehicles” and “eventually, perhaps, even to private cars.” A few decades later, while toll booths are still a cause of traffic bottlenecks, the use of radio transponders has become widespread all around the world.

–By Kathleen Esfahany