Simple Science: How E-ZPass transponders operate


Drivers heading down the Garden State Parkway may find that white-and-purple E-ZPass signs are becoming increasingly prevalent, helping to reduce toll lines and streamline payments.

E-ZPass devices are radio-frequency identification transponders. They emit radio waves that an antenna attached to toll booths can read, which reduces the need for human operators or loose change.

The receiver at a toll booth broadcasts a signal to the transponder, which then “replies” with identifying information. This tells the booth’s computer to let the vehicle go through.

The transponder itself is connected to its owner’s E-ZPass account. The company charges the transponder’s owner the appropriate toll, which it then pays to the booth’s owner.

Because the receivers are designed to read any and all E-ZPass transponders, they can read multiple devices within a single vehicle. In other words, if there are two devices in a car, both will be charged for passing through a booth

Wrapping one in foil may prevent this from happening, if a person is transporting multiple tags.

The use of E-ZPass transponders may have lead to a noticeable decrease in the amount of pollution near toll booths. Since the system is automatic, cars spend less time idling in line while drivers pay human operators their tolls.


Nikhilesh De

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