Traffic Message Channel (TMC) is a technology for delivering traffic and travel information to motor vehicle drivers. It is digitally coded using the ALERT C protocol into
RDS Type 8A groups carried via conventional
FM radio broadcasts. It can also be transmitted on
Digital Audio Broadcasting or
satellite radio. TMC allows silent delivery of dynamic information suitable for reproduction or display in the user's language without interrupting audio broadcast services. Both public and commercial services are operational in many countries. When data is integrated directly into a
navigation system, traffic information can be used in the system's route calculation.