GB2241269A - Speed limit warning system - Google Patents

Abstract

A speed limit warning system comprising an array of individually differentiable indicators adapted for roadside installation and arranged so as to be viewed one above another or one alongside another by a driver as they come into his line of sight; the indicators being so optically graded that they become progressively less easily seen and/or less easily individually differentiable from one end of the array to the other. <IMAGE>

Description

SPEED LIMIT WARNING SYSTEM Field of the Invention The invention relates to speed limit warning systems and is specifically applicable to systems adapted for roadside installation.

The term "roadside" is intended to be given a broad meaning in the context of this specification and to include within its scope any installation which is intended to be viewed by a driver as he travels along a given stretch of road. It will become apparent, as this specification continues, that a system embodying the invention could comprise components installed at relatively large distances from the literal side of the road. These are intended to be covered by the term "roadside installation" as well as systems which are installed or adapted for installation adjacent the road or carriageway edge as such.

Review of Art known to the Applicant Controlling the speed of traffic to a potentially safe level during conditions of poor visibility, for example during foggy conditions, is difficult. Systems currently in use on (for example) motorwayclass roads comprise indicators which are electrically illuminable and which. can be. operated to flash a visible warning to oncoming traffic. The flashed warning typically comprises a road-speedlimit marking in miles-per-hour format - eg "50" - and this is certainly better than nothing.

These known systems, however, have drawbacks. The flashed speed-limit marking is unaccompanied by any reason for the speed limit. The decision to select a given limit is often taking on information which is no longer accurate for the locality of the installation. The control of these flashing indicators is rarely local.

Worst of all, these known systems are an attempt at coercion in that they psychologically tell a driver that another, higher-level, unidentified personage has decided that he - the driver - must slow his speed1 now, to a level whose value he had no choice over; and which, to make matters worse, may well be quite out of line with the driver's perceived judgement of the same question.

In this day and age, such a basically authoritarian approach is asking for trouble. And it is no surprise - and is all too well known - that large numbers of drivers virtually ignore it.

The problem therefore is how to replace these known systems with systems which will be rather more effective. The solution lies in the application of non-authoritarian persuasive rather than coercive methods. The invention is based on the premise that a driver is far more likely to heed a warning if the warning can be made to appear to be voluntarily generated by him, and applied as a result of his own judgement of his road-going performance at the relevant time, than if he is merely told to do that which he supposedly ought to be doing.

Summary of the Invention According to the invention, therefore, there is provided a speed limit warning ~system comprising an array of individually differentiable indicators adapted for roadside installation and arranged so as to be viewed one above another or one alongside another by a driver as they come into his line of sight; the indicators being so optically graded that they become progressively less easily seen and/or less easily individually differentiable from one end of the array to the other.

Thus a driver will normally expect to see (ie to be able to see when conditions are sufficiently clear for safe unrestricted driving within any locally applicable overall speed limit) the whole array in-line as he habitually and quickly glances at them. This habitual checking of the indicator array could become as normal and quick an operation as the checking of roadside mileage boards, exit route indications, and other indicators which the modern driver has to read and take decisions on. If for any reason he suddenly finds that he cannot see the whole array, or cannot immediately and almost subconsciously differentiate the indicators of the array from one another as he is used to doing in safe visibility conditions, then he will himself voluntarily begin to slow down until either the conditions clear or the next indicator array confirms his diagnosis that he must travel carefully.

In one embodiment of the invention, to be described and illustrated, the indicators are positioned one behind another. In this particular embodiment they are arranged so as to be viewed one above another and, in a modified version, to be viewed alongside one another, as they come into the driver1 5 line of sight.

In this embodiment also, the indicators are differentiable by virtue of the fact that they become progressively less bright from the front of the array backwards.

Some at least of the indicators may with advantage be electrically illuminated, and all the indicators are so illuminated in the embodiment described and illustrated.

In this embodiment also, the indicators are permanently illuminated, for reasons which will be explained.

In any embodiment of the invention, some at least of the indicators may incorporate road-speed-limit markings (such as "20"; "40"; "50"; etc) and again, in the embodiment described and illustrated, all the indicators are so marked.

This embodiment, and its modification, will now be described with reference to the accompanying drawings which form part of this specification.

Brief Description of the Drawings Figures 1, 2 and 3 show the first embodiment of the invention in, respectively, side elevation; front elevation; and plan, and Figures 4 and 5 correspond respectively to Figures 1 and 2 and show the second embodiment of the invention.

Description of the Preferred Embodiments As the drawings show, an array of (in this embodiment) six permanently illuminated road-speed-limit-marked signs are arranged so that under normally safe visibility, and when viewed by drivers with sufficiently good eye sight for safe driving, all can be viewed simultaneously whilst travelling along the carriageway. The illuminated signs are arranged progressively one behind another so that "20" is nearest the roadside whilst "70" is farthest away.

The signs are therefore so optically graded that they become progressively less easily seen from one end of the array to the other, because it is harder to see the "70" sign than it is to see the "20" sign even if both of them - and all the signs in between - are in fact visible; because of the progressively increasing distance over which the viewer has to make out the successive signs.

Further optical grading is provided by the fact that the intensity of illumination of these particular signs is similarly progressive.

The "20" sign is most brightly lit whilst the "70" sign is deliberately least brightly lit. The ones inbetween follow that pattern, ie they become progressively less bright as one goes up the range of indicated speeds and away from the viewer.

Drivers travelling along the carriageway will quickly become accustomed to seeing these roadside arrays if the arrays are positioned at sufficiently frequent intervals along major roads such as motorways. They will have been told that the "70" sign is farthest away from them and that as the signs get nearer the speed limit gets less. They will also have been told that the signs have deliberately been so positioned that, in safe driving conditions and with good enough eye sight, any driver should be able simultaneously to see all of them as they come into his line of sight.

During periods of fog, as visibility gets poorer, the "70" sign first becomes invisible; then the "60"; the "50", and so on. A driver seeing a reduced number of the total array will know immediately that, although he cannot see the "faster" signs, they are still there - and they are still switched on.

He will then immediately and subconsciously slow down because that he knows that he should be able to see them.

By the same reasoning, a driver with less than perfect eye sight - who might otherwise resent being told that he really should get his eyes seen to - will be forced to admit to himself (ie without the embarrassment of having it confirmed by a third party) that he should slow down because his eye sight is not what it should be.

In both cases,, drivers are exercising their own judgement, not being coerced. The effectiveness of the system relies of course upon the drivers becoming familiar with the existence of the arrays and the perceivable visual pattern that they represent. But such systems need no day-to-day or hourly control of the kind that the known flashing warnings require. They can be installed quickly and cheaply at known accident black spots and could even be portable to test the effectiveness of the system in particular locations.

Spacing of the individual indicators would be determined by local conditions but there is no reason why several arrays could not be grouped very closely in high-risk areas.

Automatic control means, for example light-sensitive switches, could switch the indicators of the array from one intensity to another with the change from daylight to night-time conditions.

Other modifications are of course possible within the scope of the invention and will become apparent to the intended skilled addressee of this specification.

Claims (9)

1. A speed limit warning system comprising an array of individually differentiable indicators adapted for roadside installation and arranged so as to be viewed one above another or one alongside another by a driver as they come into his line of sight; the indicators being so optically graded that they become progressively less easily seen and/or less easily individually differentiable from one end of the array to the other.

2. A system according to Claim 1 and in which the indicators are positioned one behind another.

3. A system according to Claim 1 or Claim 2 and in which the indicators become progressively less bright from the front of the array backwards.

4. A system according to any of the preceding Claims and in which some at least of the indicators are electrically illuminated.

5. A system according to any of the preceding Claims and in which the indicators - or at least those of them which are illuminated if only some are illuminated - are permanently illuminated.

6. A system according to any of the preceding Claims and in which some at least of the indicators incorporate road speed-limit markings.

7. A system according to any of the preceding Claims and comprising a plurality of arrays grouped closely adjacent one another.

8. A system according to any of the preceding Claims and in which automatic control means switch the indicators from one intensity to another with changing visibility conditions.

9. A system substantially as described herein with reference to and as illustrated in the accompanying drawings.