WO2020070490A1

WO2020070490A1 - Traffic light monitor

Info

Publication number: WO2020070490A1
Application number: PCT/GB2019/052775
Authority: WO
Inventors: Stuart TROW; John Dolan
Original assignee: Invenio Systems Ltd
Priority date: 2018-10-02
Filing date: 2019-10-02
Publication date: 2020-04-09
Also published as: GB2577699A

Abstract

A traffic light monitoring apparatus is configured to monitor at least two traffic lights in a temporary traffic light system, each traffic light including a red light and a green light, and the monitoring apparatus comprises for each traffic light: a red light sensor associated with the red light of the traffic light, a green light sensor associated with the green light of the traffic light and a motion sensor. The monitoring apparatus includes a processor connected to the sensors for receipt of processor output signals therefrom, a data recording means connected to the processor for receipt of processor output signals and a power source. The apparatus includes a communications module which is configured to connect to the data recording means and to transfer processor output signals to a computer.

Description

Traffic Light Monitor

Field of the Invention

The invention relates to an apparatus for monitoring traffic ligths, and in particular to an apparatus

monitoring temporary traffic lights.

Background of the Invention

Traffic lights are deployed widely for controlling flows of traffic Typically traffic lights comprise a red light indicating that traffic should stop, a green light indicating that traffic may proceed past the fight and an amber light indicating that the status of the red and green lights will change. Traffic lights may be categorised as permanent or temporary. Permanent traffic lights are typically used at junctions, whereas temporary traffic lights are typically used where a road is being worked on. In most instances where temporary traffic fights are used, the flow of traffic needs to be controlled in two directions, i.e. when traffic is flowing in one direction it is stopped from flowing in the other direction. Typically, this is where one lane of a two lane road is closed.

Traffic fights, including temporary traffic lights, may be provided with a vehicle activation (VA) system.

A VA system allows the traffic lights to respond to the presence of a vehicle that needs to pass the traffic light and allows the traffic light to turn to green when a vehicle js detected.

The malfunction or incorrect setting up of traffic lights may cause numerous problems. For example, the flow of traffic is cither stopped or slowed, drivers may decide to disobey the instruction of the traffic light if the traffic light remains on red for too long a period. Common traffic light malfunctions include: the traffic light being stuck on green or red, no lights showing at all, the traffic lights at each end of the road works showing the same colour at the same time, red and green showing at the same time on the same traffic light, the traffic light is stuck on red while VA is on and a timed setting is off, the traffic light is stuck on red while VA is off and a timed setting is on, the duration of illumination of the red and/or green light being mismatched with the section of road that is out of use (for example, the traffic light at one end of a section of road works may be green, indicating that a vehicle may pass, but when the lights switch after the vehicle has passed the green light, an insufficient period may be allowed before the traffic light at the other end of the closed section of road turns to green. Such a malfunction may result in two vehicles meeting head on in the open lane.

It would therefore be desirable to provide arrapparatus which can detect whether traffic lights, and in particular temporary traffic lights, are functioning correctly or not. It would also be desirable to provide such an apparatus that is capable of notifying malfunctions in such a traffic light to a third party. It would also be desirable to provide such an apparatus that is capable of correcting malfunctions in such a traffic light Summary of the Invention

According to the invention there is provided a traffic light monitoring apparatus configured to monitor at least two traffic lights in a traffic light system, each traffic light including a red light and a green light, the monitoring apparatus comprising for each traffic light: a red light sensor associated with the red light of the traffic light, a green light sensor associated with the green light of the traffic light and a motion sensor, and wherein the monitoring apparatus includes a processor connected to the sensors for receipt of processor output signals therefrom, a data recording means connected to the processor for receipt of processor output signals and a power source, wherein the apparatus includes a communications module which is configured to connect to the data recording means and to transfer processor output signals to a computer.

Preferably, the communications module transfers processor output signals over a wireless network, for example a telephone network such as GPRS, 2G, 3G, 4G, 5G particularly where the computer is a remote computer, such as a cloud based computer. The computer may be local to the traffic lights and may be connected by wires or wirelessly.

The apparatus may also include a remote database and the remote database may be provided by the remote computer.

The remote computer is programmed with an algorithm and processed sensor signals form inputs to the algorithm and the algorithm which generates as outputs traffic light condition indicating signals. It is preferred that the traffic light condition indicating signals are transmitted as notifications to one or more other devices.

For example, to a mobile phone, laptop or other computer, typically of a person responsible for maintaining the set of monitored traffic lights. If the traffic lights are not functioning correctly arrangements can be made to fix or adjust them. The other device could be a traffic light controller and the algorithm outputs of traffic light condition indicating signals could form inputs to a traffic light control system operated on the traffic light controller to fix, adjust or reset the sequencing of red and green lights of the traffic lights.

Preferably, the processor assigns different values to different sensor outputs. For example, different conditions of the red and green lights of a traffic light may be assigned as follows: red light on: 1; green light on: -1; both red and green lights on: 2; neither red nor green lights on: 0.

The computer may be connected to a traffic light control system. The traffic light control system may include a vehicle activation system, that is a system which recognises the presence of a vehicle proximate a traffic light and switches the condition of the traffic light in response to the detection of the vehicle. Typically, such a traffic light control system would also include a means of timing the duration that red and green lights are on and off or off and on for respective traffic lights of a two traffic light system.

Preferably, the algorithm is configured to associate the status of the traffic light control system with the status of illumination of the red and green lights of each traffic light.

Advantageously, the algorithm is configured to generate outputs indicating traffic light statuses selected from the group comprising: no lights showing; two sets of traffic lights stuck on green; red and green lights showing on the same traffic light at the same time; a traffic light stuck on any colour; a traffic light stuck on red or green while a vehicle activation is on and a timed setting is off or vehicle activation is off and a timed setting is on; and timing is on but not allowing sufficient time for vehicles to pass through a region controlled by the traffic lights.

Preferably, the motion sensor is a LIDAR sensor.

It is preferred that the light sensors are light sensitive resistors.

Advantageously, each of the light sensors and the motion sensor are mounted in weather-proof housings. Preferably, the housing of the light sensor includes a light inlet and the material from which the housing is formed is opaque.

The light sensors may be attachable to a traffic light, for example on to one of the green light or red light or immediately adjacent thereto. The light sensors may be attached to a traffic light by means of any suitable fastener such as double-sided adhesive tape, a bracket, etc. Alternatively, light sensors may be integrated into the green and red lights.

Connections of the sensors to the processor may be wired or wireless. Where wires are used it is preferred that they are weather proof.

Brief Description of the Drawings

In the Drawings, which illustrate preferred embodiments of the apparatus of the invention, and are by way of example:

Figure 1 is a schematic representation of a set of traffic lights according to the invention;

Figure la is an exploded view of part of the traffic lights shown in Figure 1;

Figure 2 is a schematic representation of a region of a road equipped with temporary traffic lights according to the invention; Figure 3 is a schematic representation of a traffic light control and monitoring system according to the invention;

Figure 4 illustrates an analysis procedure for an apparatus as shown in Figure 2 where no lights are illuminated;

Figure 5 illustrates an analysis procedure for an apparatus as shown in Figure 2 where both green lights are illuminated;

Figure 6 illustrates an analysis procedure for an apparatus as shown in Figure 2 where one or more light is illuminated and stuck;

Figure 7 illustrates an analysis procedure for an apparatus as shown in Figure 2 where one of the lights is stuck on red while YA is on and a timing control is off;

Figure 8 illustrates an analysis procedure for an apparatus as shown in Figure 2 where one of the lights is stuck on red while YA is off and a timing control is on;

Figure 9 illustrates an analysis procedure for an apparatus as shown in Figure 2 where a timing control is on but allowing insufficient time to pass through the region of road; and

Figure 10 illustrates data collected.

Detailed Description of the Preferred Embodiments

Referring now to Figure 1, which shows a pair of traffic lights 1, 1’ each comprising a red light 2, 2’, a green light 3, 3’ and an amber light 4, 4’. The red light 2, 2’ is provided with a light sensor 5, 5’ whilst the green light 3, 3’ is provided with a light sensor 6, 6’. Each of the traffic lights 1, 1’ is also provided with a motion sensor 7, 7’.

The light sensors 5, 5’, 6, 6’ and the motion sensors 7, T are all connected to a processor 8.

The light sensors, which are in the form of light dependent resistors, are each housed in a weather proof housing 5a, which is opaque and includes a small opening 5b as shown in Figure la. A weather proof housing is fixed to each of the lights 2, 2’, 3, 3’ such that the small opening thereof faces the light such that only light emanating from the light can be sensed by the associated light sensor, that is other pathways for light to impinge on the light sensor are blocked by the housing and the manner in which the housing is mounted on the light.

In other embodiments, the light sensors could be integrated into the lights 2, 2’, 3, 3’. It is also possible that the light sensors could be mounted with respect to the lights 2, 2’, 3, 3’ in a manner that does not exclude light other than light emanating from one of the said lights 2, 2’, 3, 3’. However, in such an arrangement the processor would include a filter configured to filter out background light.

Figure 2 illustrates a set of temporary traffic lights 1, 1’ set up on a road 10 and defining a controlled works site 11. Vehicles approach the controlled works site 11 in opposing directions X, X’ with control of the vehicles through the works site 11 being controlled by the temporary traffic lights 1, 1’.

Figure 3 illustrates the electrical and electronic elements of the invention. The red light sensors 5, 5’, green light sensors 6, 6’, and motion sensor 7, which in this example is a LIDAR sensor, are connected electrically to the processor 8, which in the illustrated example is a simple programmable computer. In the example a Raspberry pi (registered trade mark) device was used. A power supply 17, preferably in the form of a battery, is connected electrically to the sensors and processor 8 to power them. In the illustrated example, the light sensors and the motion sensor are connected to the processor 8 and power supply 17 by wired connections. Alternatively, the sensors could be provided with their own power supplies with signals being exchanged with the processor 8 by a wireless connection.

The motion sensor 7 is a LIDAR sensor which senses motion by sending out a pulse of light (a pulsed laser), waiting for the light pulse to reflect off an object and receiving the reflected signal. The distance between the sensor 7 and an object (a car for example) is calculated by multiplying the time taken to send and receive the pulse of light by the speed of light. The LIDAR sensor generates information representative of traffic flows by virtue of returning a much larger distance when a vehicle is not present and a much shorter distance when a vehicle is present. The closer the vehicle is to the LIDAR sensor the shorter the distance travelled by the pulse of light to the point of reflection and hence the shorter the time taken for the reflected pulse to be registered by the LIDAR sensor. Of course, the time taken for the reflected pulse to be received when no vehicle is present will depend on the width of the road (that is the distance from the LIDAR sensor to an object capable or reflecting the issued pulse of light). Also, the time taken for an issued pulse of light to be reflected by a vehicle will depend on the proximity of the LIDAR sensor to the traffic which will be different at different work sites.

If the vehicle is stopped at a marked stop position proximate a traffic light 1, 1’ the distance to the vehicle will be shorter than when an approaching vehicle first intercepts the pulsed light signal.

The LIDAR sensor may be positioned at an angle to direction X, X’. Where 0 degrees is parallel to the direction X, X’ and 90 degrees is perpendicular to the direction X, X’ across the flow of traffic in the direction X, X’, the LIDAR sensor may be mounted between 30 degrees and 90 degrees to the direction X, X’. The processor 8 is connected to a data file 15 where signals generated by the processor are stored. In the illustrated example, the data stored to the data file 15 is transferred to another computer 18 which provides a database and for analysis of the data stored on the database.

The apparatus functions as follows:

When one of the lights 2, 3 turns on, the resistance of the light dependent sensor 5, 6 drops below a selected resistance value threshold. The threshold is dependent on the type of light, for example whether the light is an LED light or not). The fall in resistance signals to the processor 8 that the light is on. The two sensors 5, 6 on the traffic light 1 collect data on the red light and the green light.

The processor 8 stores the following data to the data file 15:

Red light on: 1

Green light on: -1

Both red and green lights on: 2

Neither red nor green lights on: 0

Data indicative of vehicle proximity to the traffic lights from the LIDAR sensor 7 is collected and stored to the data file 15 at intervals of time ranging between 1 millisecond and 1 microsecond. The time interval may be determined by the pulse emission interval of the LIDAR sensor or a sampling clock of the computer 8.

In the illustrated example, the apparatus at the traffic lights 1, 1’ includes a communications module 16 which transfers data from the data file 15 to a remote computer 18 at desired time intervals, which may be between 1 second to 24 hours. The communications module 16 is configured to connect to the computer 18, for example over a mobile phone network (GPRS, 2G, 3G, 4G, 5G, etc).

Data transmitted by the communications module 16 is recorded on a database of computer 18 (which may be a cloud based computer). The computer also receives inputs from a traffic light controller which controls the operation of the traffic lights 1, 1’. The traffic light controller sets the time that each of the traffic lights 1, 1’ is set to red and green respectively. The traffic lights 1, 1’ may be provided with vehicle activation sensors and if so, the vehicle activation sensors are connected to the traffic light controller. The computer 18 runs an algorithm which determines faults in the traffic lights 1, 1’ based on the signals recorded in the data file 15, the list of faults including:

1. No lights showing at all.

2. Both set of lights on green. 3. Red and green showing on the same light at the same time.

4. Stuck on any colour.

5. Stuck on red while vehicle activation (VA) on and timed setting off.

6. Stuck on red while vehicle activation (VA) off and timed setting on.

7. Timing is on but not allowing cars sufficient time to pass through construction zone.

The faults listed above are detected by different algorithms.

A‘no lights showing’ fault is indicated where the data from the data file shows the answers to the first three steps shown in Figure 4 are affirmative.

A‘both lights on green’ fault is indicated where the data from the data file shows the answers to the first three steps shown in Figure 5 are affirmative.

A‘red and green showing on the same light at the same time’ is indicated where the algorithm illustrated in Figure 5 is such that the first step asks,‘are both red and green lights of one traffic light showing at the same time? If the answer in step 2 is that the green light for light 1 is showing and the answer for step 3 is that the red light for light 1 is showing, then the aforementioned fault is detected.

An‘either light on any colour’ fault is indicated where the data from the data file shows the answers to the first four steps shown in Figure 6 are affirmative.

Figure 7 illustrates a condition where either of traffic lights 1, 1’ is stuck on red while vehicle activation is on and timing of the traffic lights 1, 1’ is off when the answer to the first five steps of the of the algorithm are affirmative.

Figure 8 illustrates a condition where either of traffic lights 1, 1’ is stuck on red while vehicle activation is off and timing of the traffic lights 1, 1’ is on when the answer to the first four steps of the of the algorithm are affirmative.

Figure 9 illustrates a condition where a timing control is on but allowing insufficient time to pass through the region of road when the answer to the first four steps of the algorithm are affirmative.

Figure 10 shows a graph indicating how a pair of traffic lights functions when functioning normally, which is represented by the left hand side of the graph and a traffic light malfunction on the right hand side of the graph. At the change over point, the graph changes from indicating vehicles stopped at each end of a controlled section of road, the direction of approach resulting in vehicles stopping changing periodically, to a scenario where one of the traffic lights is stuck on red.

Claims

1. A traffic light monitoring apparatus configured to monitor at least two traffic lights in a temporary traffic light system, each traffic light including a red light and a green light, the monitoring apparatus comprising for each traffic light: a red light sensor associated with the red light of the traffic light, a green light sensor associated with the green light of the traffic light and a motion sensor, and wherein the monitoring apparatus includes a processor connected to the sensors for receipt of processor output signals therefrom, a data recording means connected to the processor for receipt of processor output signals and a power source, wherein the apparatus includes a communications module which is configured to connect to the data recording means and to transfer processor output signals to a computer.

2. The apparatus of Claim 1, wherein the communications module transfers processor output signals over a wireless network, or by wires.

3. The apparatus of Claim 1 or 2, including a database and the remote database may be provided by the computer.

4. The apparatus of any preceding claim, wherein the computer is programmed with an algorithm and processed sensor signals form inputs to the algorithm and the algorithm which generates as outputs traffic light condition indicating signals.

5. The apparatus according to any preceding claim wherein the processor assigns different values to different sensor outputs, the so assigned values forming inputs to the algorithm.

6. The apparatus of Claim 5, wherein different conditions of the red and green lights of a traffic light may be assigned as follows: red light on: 1; green light on: -1; both red and green lights on: 2; neither red nor green lights on: 0.

7. The apparatus according to any preceding claim, wherein the computer is connected to a traffic light control system.

8. The apparatus of Claim 7, wherein the traffic light control system includes a vehicle activation system which recognises the presence of a vehicle proximate a traffic light and switches the condition of the traffic light in response to the detection of the vehicle.

9. The apparatus of Claim 8, wherein the traffic light control system includes a means of timing the duration that red and green lights are on and off or off and on for respective traffic lights of a two traffic light system.

10. The apparatus of any of Claims 7 to 8, wherein the algorithm is configured to associate the status of the traffic light control system with the status of illumination of the red and green lights of each traffic light.

11. The apparatus of any of Claims 8 to 10, wherein the traffic light condition indicating signals generated by the algorithm are fed back to the traffic light control system and form control inputs to said traffic light control system

12. The apparatus of any preceding claim, wherein the algorithm is configured to generate outputs indicating traffic light statuses selected from the group comprising: no lights showing; two sets of traffic lights stuck on green; red and green lights showing on the same traffic light at the same time; a traffic light stuck on any colour; a traffic light stuck on red or green while a vehicle activation is on and a timed setting is off or vehicle activation is off and a timed setting is on; and timing is on but not allowing sufficient time for vehicles to pass through a region controlled by the traffic lights.

13. The apparatus of any preceding claim, wherein the motion sensor is a LIDAR sensor.

14. The apparatus of any preceding claim, wherein the light sensors are light sensitive resistors.

15. The apparatus of any preceding claim, wherein each of the light sensors and the motion sensor are mounted in weather-proof housings.

16. The apparatus according to Claim 14, wherein the housing of the light sensor includes a light inlet and the material from which the housing is formed is opaque.

17. The apparatus according to any preceding claim, wherein the light sensors are attachable to a traffic light, on to one of the green light or red light or immediately adjacent thereto.

18. The apparatus of any of Claims 1 to 16, wherein light sensors are integrated into the green and red lights.