E-mail any questions to the help desk for a direct response – any Frequently Asked Questions and their solutions will be added to this page.

FAQ will gradually build everyone’s knowledge over time. Please ask your questions and we will obtain an expert’s answer from the membership to add here for all in the future.

Where is a TMC service available?

Take a look at our worldwide map of TMC Services Today

Where can I purchase a TMC receiver?

TMC-equipped navigation systems are available optionally or as standard on most models of all major car marques. A wide range of units is also available for after-market fitting from car radio and accessory suppliers. Some new systems are portable – based on a PDA or dedicated personal navigation system – and available from computing specialists. For further information please contact the TMC Forum who can provide you with a supplier list. Bear in mind that some systems will require expert installation.

Is TMC information better than traditional radio traffic information?

In many countries the source of information is the same for both TMC and traditional radio services. In principle, the information should therefore be the same. However:

– News readers on traditional radio get a fixed slot every hour or half hour, and have to squeeze all messages into a few minutes. Normal traffic announcements can therefore only include a small proportion of all current messages in their limited broadcast capacity.

– TMC can support up to 300 messages per hour, delivered as soon as they are created. This lets TMC services broadcast more information, such as road works, and TMC receivers can filter messages relevant to a specific local area or for the current journey.

– Some TMC service providers offer added-value information about traffic conditions using dedicated information sources.

– TMC messages can be interpreted by your navigation system, where spoken announcements cannot. This means you can usually see on a map display the severity of congestion and in many cases the receiver can work out the quickest route to your destination.

How does TMC differ from TA (traffic announcements) and TP (traffic programme)?

TMC is a “silent” traffic data system, needing a special decoder in the receiver. The Traffic Announcement (TA) feature of a standard RDS radio allows interruption of a CD or cassette tape when there is a travel report from the radio station that is currently tuned-in. Stations broadcasting traffic announcements are labelled with the TP (Traffic Programme) flag, allowing them to be selected even when listening to another station.

Will I miss traffic messages if my radio or navigation system is switched off?

No, current messages are re-broadcast continually as long as they remain relevant, and a TMC receiver can store messages in its memory.

If I go from one country to another will my TMC receiver 'roam' like my GSM phone?

In most countries and regions only one TMC service is available in a certain location. Most TMC receivers will automatically tune to the strongest TMC service. You should be able to receive free services across most of Europe as long as you have the appropriate navigation map disc. Where commercial services exist, access will depend on the partnerships and agreements established between operators and manufacturers.

Will TMC help me avoid traffic jams, does it tell me where to go?

TMC messages may include diversion advice. Many recent navigation systems offer Dynamic route guidance, which uses the TMC messages to identify problems and re-calculate the route on request, thus avoiding the congestion.

Whom do I contact if TMC is not available in my area or if my TMC receiver doesn't work?

First contact the shop or the dealer where you purchased your TMC receiver. If they cannot help then you may contact the TMC Forum, which will then do its utmost to assist you.  Additionally, some common problems are outlined below.

My GPS navigation system shows a TMC icon - but no messages are received. Why?

In order to decode TMC messages, your navigation system needs to:

1) Have the appropriate location information to decode the messages

2) Be entitled to use the TMC service being broadcast.

– If your navigation map disc is not up-to-date or doesn’t cover the area in which you are driving, then the required location information may not be available.  Therefore your system may actually be receiving the TMC messages but be unable to decode and use them.

– In some areas, such as the United Kingdom, only commercial TMC services are broadcast.  In these areas, you will only be able to receive TMC messages if the manufacturer of your navigation system (or of your vehicle, for those with original-equipment navigation systems) has made an agreement with the service provider to receive TMC information.

My GPS navigation system doesn't show a TMC icon. Why?

– Apologies for the obvious point – but check in its documentation that your navigation system is capable of receiving TMC messages

– TMC messages are received via selected FM-RDS radio broadcasts.  Therefore your navigation system needs either to receive these through its own aerial and tuner, or through a connection to a suitable external radio tuner and aerial. If your navigation system has been correctly fitted this should not be a problem.

– If you are in a remote or mountainous area, check whether you can receive a radio station which broadcasts TMC information.  For example, the ITIS TMC service in the UK is broadcast on radio station Classic FM; if you are in an area where this cannot be received then neither will your navigation system be able to receive TMC information.

How can I add TMC to my existing GPS navigation system?

Some GPS navigation systems allow you to add an external TMC receiver, if they do not already have one built-in. You will also need the appropriate software, which should be included in up-to-date map discs. A knowledgeable dealer should be able to tell you if this will be possible for your system. If you would like to receive a commercial TMC service (see the Services Today section of this site to find whether this is the case), check beforehand with the service provider that your planned combination of map disc and GPS navigation system (and, if applicable, separate TMC receiver) will enable you to receive the service.