Patent ID: 8068981

Claim:
An off-board navigation system for vehicles, comprising: at least one off board operating center; and at least one on-board unit installed on board a vehicle and which communicates with said at least one off board operating center and can be used by a user for setting target destinations; said at least one off board operating center comprising: an off-board calculating unit, which receives a user request and is designed to calculate, in response, a route on the basis of the information regarding the position of said vehicle and on the basis of geographical data present in the off board operating center itself; an off-board transceiver unit configured to transmit said route to said on-board unit; and an off board monitoring system configured to monitor constantly the traffic and road conditions of a road network of a portion of territory and to detect traffic altering events that modify the road conditions of stretches of road forming part of said road network; and an off-board processing system configured to determine, upon detection of an event that alters traffic conditions, whether said traffic altering event has occurred on a stretch of road forming part of said route supplied to said user and, in this case, to determine a point of no return (PNR) that is set along said route which corresponds to that point on the route beyond which any deviations from the route are no longer possible and beyond which said vehicle is no longer able to avoid said traffic altering event; and a point of influence (AR) in which the amount of traffic congestion along said route starts to be affected by the onset of said traffic altering event and beyond which said user is still in time to request to and to receive from said operating center an alternative route designed to avoid said traffic altering event in the case where said point of no return (PNR) has not yet been exceeded, wherein the point of influence (AR) is determined on the basis of a distance (d) that said vehicle would cover in a time (t est ) of extinction of the traffic altering event if it were to cover said route in the opposite direction from the position of the traffic altering event and if it were to travel at a pre-set speed for covering said route; and communicates such determination and associated data to the on-board unit.