GB2418515A

GB2418515A - Road vehicle sensor

Info

Publication number: GB2418515A
Application number: GB0517235A
Authority: GB
Inventors: David Stuart Smith
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-08-23
Filing date: 2005-08-24
Publication date: 2006-03-29
Anticipated expiration: 2025-08-24
Also published as: GB2418515C; GB2418515B; GB0517235D0; GB0418761D0; GB2417593A

Abstract

A vehicle sensor pre-fabricated and tested in factory before being installed in a road surface. It consists of electrically inductive coils with known, tried and tested characteristics for the sensing of road traffic vehicles of various categories. When connected to appropriate electronic equipment, the sensor assembly detects the presence of a vehicle, whether moving over the sensor or in a stationary position, and can be used to determine the speed, length and class of a vehicle. Each sensor has shape and dimensions which enable it to be fitted into a single saw-cut slot cut in a road surface. When used in a carriageway with more than one lane, then the slot is cut across all lanes with a sensor assembly fitted into each lane throughout the slot. The sensor assemblies are pre-formed in a range of dimensions allowing installation in roads and lanes with standard and non-standard widths.

Description

Road Vehicle Sensor This invention relates to a road vehicle sensing

device for the purpose of sensing the presence of a passing road vehicle, more particularly to a prefabricated sensor arrangement specifically preformed for installation into a single saw-cut slot in the road surface.

Electrically inductive loops formed from electrically insulated wire are currently used as the means by which road traffic, inclusive of but not limited to automobiles and cycles, is detected, counted and their speeds identified. The detected presence and speed of vehicles on a road are also used to set traffic signals and warning signs on that road or adjoining roads. Such electrically inductive loops are formed in situ on the road surface. Slots are saw-cut into the road surface, interconnecting to form rectangles and cable channels. Electrical cable is laid into the rectangle slots to form electrically inductive loops, and the ends of the electrical cable run in the channels to a jointing box, at the edge of the road, in which the inductive cables are joined to feeder cables. The feeder cables connect the inductive loop sensors to electronic control equipment.

The locations of usage of inductive loops generally include roads, streets, highways, motorways, tracks, thoroughfares, parking areas, access roads, forecourts and driveways.

Applications include but are not restricted to traffic signals, automatic information signs traffic monitoring and surveillance equipment, speed cameras, traffic signal stop line cameras, speed indicator signs, petrol station forecourt, home security, commercial premises security, fleet management, car park Bated access.

On a plan view, the interconnecting slots containing the electrically inductive loops can span an area of up to eight square metros. Such slots can require the closure of a road. This cutting process can cause a significant amount of traffic delays and can be costly. The slot-cutting is followed by the laying of cables into the slots. On a plan view, the width of the open gap created by a saw-cut slot can range from less than or equal to 10 millimetres to more than 10 millimetres.

The present invention proposes a road traffic vehicle, including cycle, detecting apparatus in which a vehicle, including cycle, sensing assembly is pre-fabricated and tested in a factory before being installed in a road surface. The locations of usage of the inductive loops will include roads, streets, highways, motorways, tracks, thoroughfares, parking areas, access roads, forecourts, driveways and car park entry/exit gates.

The device consists of electrically inductive coil or coils with known, tried and tested characteristics for the sensing of road traffic vehicles of various categories. The method of sensing uses electromagnetic inductance, in which the electromagnetic properties of the inductor are altered when a road vehicle passes over it. When connected to appropriate electronic control equipment, the sensor assembly detects the presence of a vehicle - whether moving over the sensor or in a stationary position over the sensor.

The coils are wound on the horizontal plane of the road surface, such that the centre line of the magnetic field protrudes perpendicularly to the road surface. Each coil is wound on a coil former whose orientation is perpendicular to the road surface.

An electromagnetic field is generated to provide a zone of detection in which the presence is road traffic vehicles are detected.

The current, voltage, phase shifting, field intensity and/or impedance properties of the electromagnetic field are modified when a road traffic vehicle enters or is within the zone of detection; The current, voltage, phase shifting, field intensity, or impedance properties ofthe electromagnetic field are restored when a road traffic vehicle exits or is outside of the zone of detection A control unit is used for detecting, identifying, analysing an/or interpreting the changes in the current, voltage, phase shifting, field intensity and/or impedance properties of the electromagnetic field and the inductive loop or loops associated with the electromagnetic field.

A feeder cable or cables is used to connect the sensor or sensors in the road with the control unit means.

Each sensor is a single pre-fabricated assembly having an elongated shape and dimensions which enable it to be fitted into a single saw-cut slot cut in a road surface, the slot forming a groove or encapsulation. On a plan view, the width of the pre-fabricated sensor assembly or single loop can range from less than or equal to 10 millimetres to more than 10 millimetres. It appears as an elongated loop of electrical wire. The sensor width will range between I millimetre and 1000 millimeters. Its length will be less than, equal to or greater than the width of a road lane.

A single-lane sensor assembly is pre-formed to fit across a single lane and to occupy a single slot cut into the road surface. A multi-lane sensor assembly is pre-formed to fit across two or more lanes and to occupy a single slot cut into the road surface. One or more coils may be contained within a single assembly, which may then be installed in a single lane or in each of a number of lanes. The orientation of the saw- cut slot, and hence the sensor, can be either transverse, at a right angle to the direction of traffic flow; longitudinal, in the direction of traffic flow; or diagonally to the direction of traffic flow.

When the single-lane assemblies are used in a carriageway with more than one lane, then a single slot is cut across all lanes with a sensor assembly fined into each lane throughout the slot.

The pre-formed sensor assemblies will have either standard dimensions suitable for most roads or road lanes, or they may be designed to fit specific road or lane widths.

Once fitted into the slot, the sensor assembly is covered with protective materials suitable to act as part of the permanent road wearing course to be driven over by road traffic.

The sensor is suitable for use with electronic control or processing equipment which can deduce the speed of each passing vehicle and with equipment which can deduce the length of each passing vehicle.

Each loop or pair of loops in a lane currently requires a feeder cable to connect the loop or loops to the electronic control equipment. For example, if a loop is installed in one lane of a road, then one feeder cable is required. If a loop is installed in each of two lanes of a road, then two feeder cables are required, and so on. Loops in the same lane, but at different locations, require their own feeder cables. More lanes mean more feeder cables, each routed back, as individual circuits, to the control equipment.

The present invention has a means by which a single feeder cable would be used to connect multiple sensors to the control equipment. A feeder cable extends from the control equipment and terminates at the first sensor. The same feeder circuit extends from the first sensor and terminates at the second sensor. The same feeder circuit extends from the second sensor, and so on to the final sensor on the feeder circuit.

The present invention allows feeder cable lengths in excess of 2000 metros. Currently, feeder cable lengths are limited to a maximum of 200 metros.

Claims

I. A pre-fabricated vehicle detection apparatus which is installed in a pre-formed or saw-cut slot groove or encapsulation in a roadway or at a car park entry or exit gate with one or more lanes consisting of: a sensor in which an electromagnetic field is generated to provide a zone of detection in which the presence is road traffic vehicles are detected; a sensor in which the current, voltage, phase shifting, field intensity and/or impedance properties of the electromagnetic field are modified when a road traffic vehicle enters or is within the zone of detection; a sensor in which the current, voltage, phase shifting, field intensity, or impedance properties of the electromagnetic field are restored when a road traffic vehicle exits or is outside of the zone of detection; a control unit means of detecting, identifying, analysing an/or interpreting the changes in the current, voltage, phase shifting, field intensity andlor impedance properties of the electromagnetic field and the inductive loop or loops associated with the electromagnetic field; a feeder cable or cables is used to connect the sensor or sensors in the road with the control unit means; a means of allowing more than one sensor to share one feeder cable; an assembly of one or more electrically inductive coils each wound on a coil former whose orientation is perpendicular to the road surface; an assembly of one or more electrically inductive coils each with its primary magnetic field axis oriented perpendicularly to the road surface; an assembly of one or more electrically inductive coils each wound on the horizontal plane of the road surface; a sensor with elongated shape and dimensions of between I millimetre and 30 millimetres which enable it to be installed into the slot in the road surface, which has matching dimensions;

a single continuous pre-cut or saw-cut slot cut across one or more road lanes into which the sensor or sensors are installed; and a sensor in which one or more coils may be contained within a single assembly, which may then be installed in a single lane or in each of a number of lanes;
2. A pre-fabricated vehicle detection apparatus as claimed in claim I in which: the present invention has a means by which a single feeder cable would be used to connect more than one sensor to the electronic equipment; a feeder cable extends from the control equipment and terminates at the first sensor; the same feeder circuit extends from the first sensor and terminates at the second sensor; the same feeder circuit extends from the second sensor, and so on to the final sensor on the feeder circuit; and feeder cable lengths are in excess of 2000 metros.
3. A pre-fabricated vehicle detection apparatus as claimed in claim I which is fitted within the limits of each lane within the single continuous slot.
4. A pre-fabricated vehicle detection apparatus as claimed in claim I which is fitted across the combined width of two or more lanes throughout the length of the single continuous slot.
5. A pre-fabricated vehicle detection apparatus as claimed in claim I in which the sensor is suitable for use with electronic equipment which can deduce the speed or length of each passing vehicle.