Red light warning system based on predictive traffic signal state data
Methods and systems are disclosed for generating a timely and reliable warning message before a traffic control signal changes to a red light state. A preferred process leverages traffic signal state data, state change predictions, and signal timing plans. The warning message may be distributed for various uses by downstream users and applications.
1. A system for generating a warning message before a traffic control signal changes to a red light state, comprising:
a red light warning server system including an operating system program and a processor operable under control of the operating system, and further including an analysis program stored in the server system and executable by the processor;
a communications interface coupled to the red light warning server system and configured for communications with a central traffic management center to download a signal timing plan for a selected traffic signal to the red light warning server system, the selected traffic signal associated with a corresponding intersection, and to download current signal state data from the selected traffic signal to the red light warning server system, wherein the current signal state data includes a current signal state for each phase of the selected traffic signal;
the communications interface further arranged to receive prediction data associated with the selected traffic signal, the prediction data generated by emulating operation of a field signal controller (FSC) that controls the selected traffic signal or by statistical methods based on storing historic data for the selected traffic signal;
the communications interface further coupled to the red light warning server system to enable transmitting a red light warning message to a downstream system;
the analysis program comprising software code configured to analyze the downloaded signal timing plan, wherein the analysis includes, based on the signal timing plan, forming derived rules that include (a) identification of predicted state changes that are certain to occur; (b) identification of state changes that begin a fixed-time interval signal control event; and (c) identification of state changes; and
a warning message software component stored in machine-readable memory accessible to the red light warning server system for execution by the processor to process the received prediction data based on the derived rules and the current signal state data, the warning message software component configured to:
determine an expected state change of the selected traffic signal to a red signal state that is certain to occur; based on the expected state change of the selected traffic signal to the red signal state that is certain to occur, to generate the red light warning message; and associate the generated red light warning message to the selected traffic signal;
apply a timestamp to the generated red light warning message, the timestamp based on receiving the current signal state data;
transmitting the time-stamped, generated red light warning message to a downstream application for use in a vehicle;
wherein the downstream application is configurable, in a case of a non-autonomous vehicle, to cause display of a message in the vehicle based on the time-stamped, generated red light running warning message; and
in a case of an autonomous or semi-autonomous vehicle, to provide the warning message to operational logic to affect controlling the vehicle ahead of the corresponding intersection.
2. The system according to claim 1 and further comprising:
a first datastore operatively coupled to the red light warning server system to store the signal timing plan; and
a second datastore operatively coupled to the red light warning server system to store the derived rules.
3. The system according to claim 1 and wherein the communications interface is configured to download the current signal state data for all phases of the selected traffic signal and then periodically download an updated set of the current signal state data from the central traffic management center.
4. A computer-implemented method comprising the steps of:
providing a red light warning server system having a processor and machine-readable memory coupled to the processor, the machine-readable memory storing instructions that, when executed by the processor, cause the processor to carry out the following steps:
receiving a set of predicted traffic signal state data for a selected traffic signal from a traffic signal prediction process, the selected traffic signal located at an intersection, and the traffic signal prediction process comprising emulating a field signal controller (FSC) associated with the selected traffic signal and or a statistical process based on historical state data of the selected traffic signal;
wherein the predicted traffic signal state data indicates, for each phase of the selected traffic signal, a current signal state, and an expected signal state change to a next signal state; and
wherein the predicted traffic signal state data further includes, for each phase of the selected traffic signal, a predicted time interval remaining until the expected signal state change;
applying a timestamp to the predicted traffic signal state data received from the prediction process;
accessing a signal timing plan of the selected traffic signal stored in a first database;
deriving a set of rules from the signal timing plan and storing the derived rules in a derived rules per signal database, the derived rules including (a) identification of predicted state changes that are certain to occur; (b) identification of state changes that begin a fixed-time interval signal control event; and (c) identification of state changes;
based on the derived rules selecting from the predicted traffic signal state data an expected state change that is certain to occur;
based on the derived rules, determining whether the selected expected state change that is certain to occur is one that will trigger a start of a fixed-time signal control event;
based on a determination that the selected expected state change will trigger the start of a fixed-time signal control event, determining, based on the derived rules, whether at a conclusion of the fixed-time signal control event, the selected traffic signal will change state to a red signal state;
based on a determination that the fixed-time signal control event will conclude with the selected traffic signal changing state to the red signal state:
generating a red light warning message associated with the selected traffic control signal;
applying the timestamp to the red light warning message; and
transmitting the time-stamped red light warning message to a downstream application;
in a case of a non-autonomous vehicle, displaying a message in the vehicle based on the time-stamped red light running warning message; and
in a case of an autonomous or semi-autonomous vehicle, providing the time-stamped warning message into operational logic for controlling the vehicle ahead of the intersection.
5. The method of claim 4 wherein transmitting the time-stamped, red light running warning message includes transmitting the time-stamped, red light running message to a server for communication to at least one vehicle in a vicinity of the traffic control signal.
6. The method of claim 4 including periodically updating the predicted traffic signal state data from the prediction process; and after each update of the predicted traffic signal state data repeating the steps of:
selecting from the received output data an expected state change that is certain to occur, determining whether the selected expected state change that is certain to occur is one that will trigger a start of a fixed-time signal control event, and determining whether at a conclusion of the fixed-time signal control event, the selected traffic signal will change state to a red signal state.
7. The method of claim 6 wherein the predicted traffic signal state data from the prediction process is updated approximately once per second.
8. The method of claim 4 including providing in the time stamped red light warning message an estimated time interval remaining until the selected traffic signal state is expected to change state to the red state.
9. The method of claim 4 wherein the fixed-time signal control events comprise a fixed yellow time for a given phase of the FSC.
10. The method of claim 4 wherein the fixed-time signal control events include an “all-red” period during which the signal heads of all phases of the selected traffic control signal remain red for a predetermined period to allow traffic to clear the intersection.
11. The method of claim 4 wherein the fixed-time signal control events include a fixed timer wherein the phase sequence and splits, comprising green signal state duration, plus yellow signal state duration, plus all-red signal state duration, remain the same.
12. The method of claim 4 wherein the fixed-time signal control events include a predetermined signal switch time.
13. The method of claim 4 wherein transmitting the time-stamped red light warning message utilizes a web service that enables wireless communication with in-vehicle computers that have wireless internet access.
14. The method of claim 4 wherein the time-stamped red light warning message is packaged as a separate add-on to a dedicated short range communication (DSRC) broadcast radio in a roadside unit (RSU).