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How E-ZPass Works

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No Change, No Problem

By installing electronic toll-collection systems, government agencies believe that traffic will move faster. The idea is that even if commuters have to slow down for the toll booths, they can get through faster with a system like E-ZPass. Motorists no longer have to worry about stopping to deposit or hand over the toll -- and there is certainly no searching the car for loose change. As long as they've paid on their E-ZPass account, they just have to rely on the lane antenna to read the signals from the transponder.

Here's how the system works:

  1. As a car approaches a toll plaza, the radio-frequency (RF) field emitted from the antenna activates the transponder.
  2. The transponder broadcasts a signal back to the lane antenna with some basic information.
  3. That information is transferred from the lane antenna to the central database.
  4. If the account is in good standing, a toll is deducted from the driver's prepaid account.
  5. If the toll lane has a gate, the gate opens.
  6. A green light indicates that the driver can proceed. Some lanes have text messages that inform drivers of the toll just paid and their account balance.

The entire process takes a matter of seconds to complete. The electronic system records each toll transaction, including the time, date, plaza and toll charge of each vehicle. Typically, consumers maintain prepaid accounts. A yellow light or some other signal will flash to indicate if an account is low or depleted.

The rules regarding how fast you can pass through the toll plaza vary from system to system. Some traffic agencies allow drivers to pass through the system at 55 miles per hour (86 kph). Others want you to slow down to 30 mph (48 kph), or even 5 mph (8 kph).

These lanes are monitored using video cameras. Some states allow cars to drive right through the toll plaza as the antenna detects the transponder. If you try to go through the plaza without a transponder, the camera records you and takes a snapshot of your license plate. The vehicle owner then receives a violation notice in the mail.


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