I have not experienced a TMC event yet but this is what the system is meant to do.
USING TMC
Dynamic route guidance
Dynamic route guidance will calculate an alternative route to avoid a traffic event when
the system receives an event warning. The system calculates a new route for all
sections. However, if any way points are set, the system calculates for the next way point.
If the event on route is serious (closed road) or if the new route is shorter than the current one
and the current one was not recalculated within the last 5 minutes, then a message to confirm
the new route will be displayed. This pop-up message will be displayed for 10 minutes and
if the new route is not rejected, then the vehicle will follow the new route.
The TMC Event icons appear on the navigation map display to indicate the location and nature
of a TMC event. TMC Event icons will appear on the map, even if the event does not occur on your route.