GB2137005A - Traffic signalling system - Google Patents

Abstract

A system for warning the driver of a high vehicle that he is approaching an overhead obstruction, such as a low bridge 9. A sensing arrangement 2, 3, including for example a light beam set at the maximum clearance height, is located well in advance of the obstruction and connected to trigger audible and visual warnings 7, 8, adjacent to the roadway and on the obstruction 9. When the sensing beam is broken by an excessively high vehicle the warnings are triggered to alert the driver to the danger of a collision. <IMAGE>

Description

SPECIFICATION Traffic signalling system The invention relates to a traffic signalling system particularly intended as an advance alert to drivers of high vehicles to the danger of collision with a relatively low obstruction.

A cause of road traffic accidents are collisions with overhead obstructions such as bridges and motorway sign gantries with excessively high vehicles or vehicles carrying high loads. Such incidents are a problem particularly in countries where there is a lack of regulations governing the maximum height of the vehicle or its load and drivers are unaware of danger when approaching a relatively low bridge or the like.

According to the present invention there is provided a traffic signalling system to alert a high vehicle or a vehicle carrying a high load approaching an overhead obstruction comprising in front of the obstruction in the intended direction of travel sensing means adapted to detect a high vehicle and energise traffic signalling means in response to said passage of such a vehicle.

Preferably the sensing means comprises a photoelectric or like apparatus having a beam arranged to be interrupted when a passing vehicle has a height greater than a predetermined level.

The invention and how it may be carried into practice will now be described, by way of example only, with reference to the accompanying drawings in which: Fig. 2 shows a schematic view of the signalling lights and bridge sign as seen from a vehicle adjacent the sensing means of Fig. 1.

Referring now to the drawings the traffic signalling system comprises sensing means generally indicated at reference 1 consisting of a co-operating light source 2 and photo-electric sensor 3 positioned on opposite sides of a carriage-way 4 so that a light beam 5 extends laterally across the full width of the carriage-way.

The light beam 5 is positioned at a height above the carriage-way surface which defines a predetermined height, the photo-electric apparatus itseif, the light source 2 and sensor 3 may be mounted upon elevated supports directly facing each other at the predetermined height or, alternatively, they may be positioned at ground level and a system of mirrors used to position the light beam 5 at the desired height. This sensing means 1 is positioned some distance in advance of an obstruction, generally indicated at 6 and which for example may be a motorway bridge or overhead sign gantry, which it is desired to protect from collision with excessively high vehicles or loads.

Intermediate the sensing means 1 and the bridge 6 are a set of traffic light signals consisting of a pair of elevated lights 7 and 8 positioned on opposite sides of the carriage-way and at a sufficient distance after the sensing means 1 so that they are clearly visible from the driving position of a vehicle passing the sensing means.

Mounted on or immediately adjacent to the bridge 6 is an illuminable "STOP" sign 9 which may bear a suitable legend such as "STOP HIGH LOAD" and may also include appropriate symbols.

Again, referring to Fig. 2, this sign is also clearly visible from the driving position of an approaching vehicle.

The signalling system is controlled and operated by apparatus, not shown in the drawings, but which will now be described. The illuminable sign 9 and the traffic lights 7 and 8 are connected to a source of power via a means for controlling their energisation which in turn is connected to apparatus, preferably electrical or electronic, which is operatively responsive to the output of the photo-electric sensor 3 such that when the beam 5 is interrupted the lights 7 and 8 are energised and the sign 9 illuminated. The traffic lights 7 and 8 flash when energised, and may be of appropriate warning colour e.g. red, in order to attract the attention of a vehicle driver.

The signalling system may also include audible warning means such as an alarm bell or siren which is energised at the same time as the traffic lights and sign.

The system may include means, manually operable, to de-energise the warning lights etc.

and/or may include a time delay switch arranged to automatically de-energise the system after a predetermined time delay, say two minutes.

In operation of the system the light beam 5 is set at a predetermined height which would be safe for a vehicle to pass under the bridge 6. Consider now an excessively high vehicle approaching the bridge in the intended direction of traffic flow indicated by arrow 10, when this vehicle reaches the sensing means 1 the light beam 5 is interrupted and the photo-electric sensor 3 responds by producing an output signal to the control apparatus which reacts by energising the flashing traffic lights 7 and 8 and illuminating the "STOP" sign 9.

The driver of the vehicle having as his field of vision the view schematically illustrated in Fig. 2 sees the flashing lights 7 and 8 and the illuminated stop sign which is facing him on the bridge 6 and is thereby warned of the danger of collision of his vehicle with the bridge structure. It is the intended procedure that the driver shall park his vehicle on the side of the road or on the hard shoulder before reaching the bridge so that effective steps may be taken to reduce the height of the vehicle load before proceeding. It is general that flashing red lights on a motorway, for example, is an indication that all traffic must immediately stop.When the vehicle is safely parked at the side of the road and the danger of collision with the bridge or structure is effectively removed the signalling system may be deenergised allowing other traffic to continue, alternatively after the predetermined delay period the signalling system is automatically deenergised to the same effect.

Clearly the sensing means 1 and traffic lights 7 and 8 must be positioned far enough in advance of the obstruction to accommodate the braking distance of any vehicle likely to activate the system. It is therefore suggested that the sensing means 1 may be positoned at approximately 200 metres in advance of a bridge and the flashing traffic lights at approximately 1 50 metres in advance. The safe height for clearance under a bridge will obviously be determined ultimately by available head room otherwise local or national regulations may set a maximum vehicle or load height. typically 5.5 metres. Also there may be local or national regulations concerning the symbols and/or legends of the illuminated sign. In one embodiment for example the illuminated sign bears the legend "STOP HIGH LOAD" in both English and Arabic.

Claims (8)

1. A traffic signalling system to alert a high vehicle or a vehicle carrying a high load approaching an overhead obstruction comprising in front of the ebstruction in the intended direction of travel sensing means adapted to detect a high vehile and energise traffic signalling means in response to said passage of such a vehicle.

2. A system as claimed in Claim 1 wherein the sensing means comprises photo-electric or like apparatus having a beam arranged to be interrupted by a passing vehicle having a height greater than a predetermined level.

3. A system as-claimed in Claim 1 or Claim 2 wherein the traffic signalling means comprises a visual indication intermediate the obstruction and the sensing means in the normal field of view of the vehicle's driver.

4. A system as claimed in Claim 3 wherein the visual indication comprises flashing traffic lights.

5. A system as claimed in Claim 3 or Claim 4 wherein the visual indication includes an illuminable warning sign or an adjacent to the obstruction.

6. A system as claimed in any preceding claim wherein the signalling means includes audible warning means.

7. A system as claimed in any preceding claim including timing means connected to de-energise the signalling system after a predetermined delay.

8. A system substantially as hereinbefore described with reference to the accompanying drawings.