The invention relates to traffic information devices.
The known traffic information devices can be split into two main categories:
those essentially designed to give motorists routing information, these systems generally being fitted on board the vehicles and, as applicable, capable of receiving qualitative information relating to the weather forecast, the existence of works on certain sections of the road network and congestion in the road network,
and those designed to provide information relating to journey times in a predetermined road network.
It is to this latter category that the traffic information device proposed by the invention belongs.
The known devices of this type come in the form of stationary illuminated display panels, which display an estimated journey time between the point at which they are located on the one hand and one or more other predetermined points of the road network on the other.
However, these information devices have the following disadvantages:
they can not be consulted by a motorist until he is already on the road network in question or in its immediate vicinity, which means that it is generally too late for the motorist to abandon his journey or easily change his itinerary if traffic on the relevant road network proves difficult: more generally, these existing devices are designed to give users immediate, up-to-date information about the relevant road network but they do not enable motorists to plan their journey in advance taking advantage of the best routes,
and these display panels provide only incomplete information to motorists who are not going to predetermined destinations for which a journey time is displayed.
Documents FR-A-2 726 382 and WO-A-96 17315 also describe on-board xe2x80x9cnavigationxe2x80x9d systems for vehicles but these systems are complex and expensive and do not provide the user with information about the actual journey times.
The specific objective of the present invention is to alleviate these disadvantages.
To this end, the invention proposes a traffic information device, designed to provide information relating to journey times in a predetermined road network, which is sub-divided into a plurality of sections linked one to the other, characterised in that it comprises a portable radio-messaging receiver having:
receiving means for receiving radio messages,
at least one memory for storing the messages received,
an electronic central unit for processing these messages,
a control interface enabling a user to control the central unit,
and a screen for displaying the information resulting from at least some of the messages received, depending on instructions entered by the user via the control interface, and in that the receiver memory contains:
topological data specific to the road network in question, this data including at least an identification code for a point of departure and a point of destination for each section of the road network,
as well as digital data representative of journey times on the sections of the road network, referred to as basic journey times
and in that the central unit of the receiver is set up to:
detect certain predetermined radio messages containing at least digital information representative of the updated basic journey times,
update said stored digital data representative of the basic journey times depending on the digital data received,
and, depending on a desired departure point and destination point set in said central unit by the user through the control interface, to:
determine which sections of the road network should be used between this desired starting point and this desired destination point,
compute an overall journey time equal to the sum of the basic journey times on said sections to be used between the desired departure point and the desired destination point,
and display at least this overall journey time on the screen.
As a result of these provisions, motorists can plan and optimise their journeys, having a precise idea of their journey time in advance.
In preferred embodiments of the invention, there is also the option of using in addition one and/or another of the following functions:
the stored digital data and the digital information received include a basic journey time for each section of the relevant road network;
at least the digital information received includes a traffic speed on each section of the relevant road network, the memory of the receiver also incorporating the length of each section of the road network;
the device is designed to be used within a road network in which several routes may be used between at least certain starting points and certain destination points, the central unit of the receiver being set up, depending on the desired starting point and destination point, to:
determine the different possible routes between the desired starting point and destination point and determine for each of these routes the sections of the road network which will be used between the desired starting point and destination point,
compute an overall journey time for each possible route across all said sections between the desired starting point and destination point,
determine which is the best route of all said possible routes, for which the overall journey time will be the shortest,
and display at least this optimum route and the corresponding journey time on the screen;
the central unit is set up to display on the screen several possible routes between the desired starting point and destination point as well as the overall journey times corresponding to these possible routes;
the central unit is set up to display on the screen a diagram representative of at least one part of the relevant road network, this diagram showing the different sections of said part of the road network by lines whose visual attributes correspond to the flow rates of traffic on said sections;
the central unit is set up to display on the screen a schematic map of at least a part of the relevant road network, this map showing two symbols corresponding respectively to the locations of the desired points of departure and destination;
the memory of the receiver contains at least one predetermined route, identified by its point of departure and its point of destination, the central unit being set up to:
allow the user to select this predetermined journey directly without having to select the starting point and destination point in succession,
and display the overall journey time corresponding to this predetermined journey;
the central unit is set up to detect certain predetermined radio messages carrying new information relating to the topology of the road network and to update the topological data contained in the memory of the receiver on the basis of these messages;
the device consists of a casing of a weight of less than 100 grams, in which the control interface is a simplified keypad having less than ten keys;
the device has indicating means to attract the attention of the user and the central unit is set up to:
store at least the last overall journey time TO looked up by the user,
on the basis of digital data representative of the updated basic journey times received by radio, update this last overall journey time in cycles, thereby determining an updated overall journey time T,
and activate the indicator means if the overall journey times T0 and T are at variance by a time xcex94T greater than a certain limit,
the receiver memory includes data indicating the time at which the basic journey times were last updated in said memory, the central unit being set up, when computing and displaying an overall journey time, to display a warning message if at least one of the basic journey times taken into account in this overall journey time has not been updated for a predetermined time preceding this computation point;
the receiver memory includes data relating to the accessibility of certain parts of the road network, the central unit being set up to:
detect certain predetermined radio messages containing information relating to said accessibility data and update the stored accessibility data on the basis of these messages,
and, when it displays the overall journey time between a desired point of departure and point of destination, display in addition at least some of the accessibility data relating to the parts of the road network falling between the desired point of departure and point of destination;
the central unit is set up to determine an average traffic speed on each section of the road network and to display a warning message if the average traffic speed on at least one of the sections falling between the desired point of departure and point of destination is lower than a predetermined threshold value.