New York City officials say they have devised an alert system using the existing Taxi TV.
A message will flash on the screen any time a driver tacks on an extra charge.
The message will tell riders to call 311.
Last month, the city said several drivers were caught charging riders for tolls for bridges and tunnels that weren't used.
Authorities say cab driver Emad Wanass charged his passengers for extra tolls 273 times in a six-month span.
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