GB2229843A - Vehicle overheight warning - Google Patents

Abstract

A vehicle overheight warning system for protecting an overhead obstacle (e.g. low bridge 2) against collision with an overheight vehicle comprises emitters 10 for transmitting beams across an approach road to detectors 11 and a power and control unit 19. The control unit 19 comprises a decision array for receiving different combinations of detector 11 output signals at a multi-line input of the decision array to provide output signals to drive a vehicle warning sign 12 to alert the driver. <IMAGE>

Description

WARNING SYSTEM The present invention relates to warning systems suitable for use in protecting bridges and the like against damage thereto from overheit vehicles attempting to pass thereunder.

Although low bridges are all provided. as a matter of course.

with suitable warning signs indicating the maximum safe height of vehicle which can pass thereunder. larae numbers of such bridges continue to suffer damage every year from overheight vehicles colliding therewith often with very serious consequences resulting not only in major traffic disruption both above and below the bridge but sometimes also in derailment of the overhead traffic.

There is accordingly a need for a warning system for alerting drivers of overheight vehicles approaching such low bridges of their overheight status in relation to the bridge they are approaching. In principle a simple detector beam set at a suitable height so as to be broken by an excessively high vehicle passing it and connected to a warning device which it then set off. could be used to achieve this objective. In practice though there are many substantial problems in avoiding false alarms which would give rise to an inclination amongst drivers to ignore the warnin. whilst at the same time ensuring proper and reliable operation under a wide variety of climatic and environmental conditions.At the same time it is important that the system should be of a more or less standard form in order to allow reasonabiy economic production and installation in a very wide variety or different road layouts.

It is an object of the present invention to avoid or minimize one or more of the above problems.

The present invention provides a vehicle overheight warning system suitable for use in protecting an overhead obstacle against collision with a vehicle travelling along an approach route towards the obstacle, which system comprises a plurality of vehicle detector beam emitter means disposed for transmitting. in use. vehicle detector beams across said approach route. at at least two horizontally spaced apart positions and a corresponding plurality of detector means each of which is aligned with a respective emitter means for detecting a vehicle detector beam remitted therefrom and providing an output indicating reduction in the beam strength during passage of a moving object through said beam. in use of the system. and a control means formed and arranged for monitoring the detector outputs and driving a vehicle warning signal output means upon detection of an overheight vehicle so as to alert the driver of said vehicle to an overheight condition, wherein said control means comprises a decision array means formed and arranged for receiving input signal logic words corresponding to different combinations of detector output signals at a multi-line input of the decision array means and routeing signal means through said array means in predetermined manner to provide different output signal logic words at a multi-line output of said decision array means connected at least to a plural its of warning signal output means drive connections for driving different warning signals corresponding thereto.

Various forms of decision array means may be used in accordance with the present invention including dedicated "hardwired" logic array means. More conveniently though there are used configurable logic array means or most preferably suitably configured memory means such as erasable programmable read only memory (EPROM) means configured as a decision array with different memorv addresFes (corresponding to different input signal combination. or logic wordsi providing different output signals combinations on a multi-line output.

With a warning system of the present invention a wide variety of different installation configurations and different detector signal inputs may be readily catered for in the same apparatus thereby permitting a high degree of reliability in operation at reasonable cost.

Preferably the decision array means has output lines connected to visual display means e.g. light emitting diodes formed and arranged for indicating the operational status of the apparatus to facilitate checking of the correct functioning of the system.

Various forms of warning signal display means may be used.

Generally though there is used an illuiinated display of some form in order to attract maximum attention from the vehicle driver concerned. For example there may be used a bulb or flip disc matrix. Desirably though there is used a fibre optic system as this can provide a high intensity warning signal and is relatively easy to maintain.

In order to enable the system to detect high vehicle transit under a wide variety of ambient ll-Jhtln.: conditions. climatic conditions e.g. rain. snow. or mist. and different detector optic conditions (including more or less heavy soiling of the optic) the system desirably includes compensation means formed and arranged for adjusting t transient vehicle detector beam reduction required for tripping of the detector to provide a vehicle presence output signal. according to the steady state beam intensity detected under the prevailing conditions.

Further preferred features and advantages of the invention will appear from the following detailed description given by way of example of a preferred embodiment illustrated with reference to the accompanying drawings in which: Fig.l is a general layout plan of a typical multi-sign installation of the invention: Fig.2 is a schematic perspective view of a basic system of the invention; Fig. 3 is a schematic block circuit diagram of the main parts of detector control circuit of the system of Figs 1 and 2: and Fig. 4 is a more detailed view of the decision array means part of the circuit of Fig. 3.

Fig. 1 shows a road layout 1 part of which passes under a low bridge 2 which requires to be protected against overheight vehicles 3 approaching from three different directions.

Accordingly each of the three approach routes 4.5.6 is provided with a warning signal unit 7.8.9 compriina an emitter 10. detector 11 and warning sign 12 connected. 13 to the detector 41. In more detail (see Fig.2) the emitter 10 comprises a power and control unit 14 mounted on a pole 15 at one side 16 of the road 17 with two laterally spaced apart.

along the road 17. infra-red (IR) beam emitter devices 18 and the detector 11 also has a power and control unit i9 mounted on a pole 20 with two laterally spaced IR beam detector devices 21 aligned with IR beams 22 from respective ones of the emitter devices 18. at the other side 23 of the road 17.

The detector 11 is connected hy land-line 13 to the warning sign 12 which is mounted on a short pole 24 a suitable distance along the road towards the bridge 2 sufficient to allow the sign 12 to be switched on and for the vehicle driver to see it in good time before he reaches the bridge 2.

In more detail the detector control means includes a decision array means 25 (see Firs 3 and 4i formed and arranged for receiving input signal logic words corresponding to different combinations of detector output signals at a multi-line input 26 of the decision array means 25 and routeing signal means through said array means in predetermined manner to provide different output signal logic words at a multi-line output 27 of the decision array means 25 connected to a plurality of warning signal output means drive connections 28 via a drive logic unit 29 for driving different warning signals corresponding thereto. Thus for example the second warning sign unit 8 on the West approach road 5 could have one warning signal showing a fibre optic illuminated legend "HIGH VEHICLE DIVERT RIGHT" for a period of say 20 seconds when a high vehicle is detected under normal operating conditions and another signal showing "HIGH VEHICLES CHECK HEIGHT" continuously when the decision array 25 receives an input signal combination corresponding to a fault condition such as low beam intensity received continuously at both detector devices z1.

Claims (7)

1. A vehicle overheight warning system suitable for use in protecting an overhead obstacle against collision with a vehicle travelling along an approach route towards the obstacle, which system comprises a plurality of vehicle detector beam emitter means disposed for transmitting, in use, vehicle detector beams across said approach route, at at least two horizontally spaced apart positions and a corresponding plurality of detector means each of which is aligned with a respective emitter means for detecting a vehicle detector beam emitted therefrom and providing an output indicating reduction in the beam strength during passage of a moving object through said beam, in use of the system, and a control means formed and arranged for monitoring the detector outputs and driving a vehicle warning signal output means upon detection of an overheight vehicle so as to alert the driver of said vehicle to an overheight condition, wherein said control means comprises a decision array means formed and arranged for receiving input signal logic words corresponding to different combinations of detector output signals at a multi-line input of the decision array means and routeing signal means through said array means in predetermined manner to provide different output signal logic words at a multi-line output of said decision array means connected at least to a plurality of warning signal output means drive connections for driving different warning signals corresponding thereto.

2. A vehicle overheight warning system as claimed in claim 1 wherein said decision array means comprises a configured memory means formed and arranged with different memory addresses.

3. A vehicle overheight warning system as claimed in either claim 1 or claim 2 wherein said decision array means comprises an erasable programmable read only memory (EPROM) programmed with different memory addresses, corresponding to different input signals and providing different output signals.

4. A vehicle overheight warning system as claimed in any one of claims 1 to 3 wherein said decision array means is provided with status signal output means formed and arranged for providing output signals indicating the steady state detector beam strength(s) monitored by the detector means, said status signal output means being connected to status display drive means for processing status signals received from said status signal output means so as to drive a visual display means to provide a plurality of visual status signals corresponding to different levels of detector beam strength thereby to provide an indication of the operational status of the detector beam emission and detection means.

5. A vehicle overheight warning system as claimed in any one of claims 1 to 4 wherein the vehicle warning signal output menas of the decision array means is formed and arranged to drive an illuminable warning display comprising a plurality of light emmision sources proximal a multiplicity of elongate optical fibres, wherein a plurality of groups of distal ends of the multiplicity of said fibres is formed and arranged to define a sequence of predetermined alphanumeric characters on a screen of said display so as to define a warning message.

6. A vehicle overheight warning system as claimed in any one of claims 1 to 5 wherein the control means is provided with compensation means formed and arranged for adjusting the transient vehicle detector beam reduction required to activate the detector to provide a vehicle presence output signal, according to the steady state beam intensity detectable under a range of ambient lighting conditions.

7. A vehicle overheight warning system substantially as described hereinbefore with particular reference to the accompanying drawings.