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ilp archive : journals

public lighting no. 39 vol. 10: conference issue part 2
October-December 1945

Editorial p105
Accidents and Street Lighting / Make Side Roads Safe p105
Every Public Lighting Engineer should make himself acquainted with the statistics of road accidents, which are issued regularly by the Ministry of War Transport. These serve as a pointer to the success, or otherwise, of methods adopted to overcome street accidents.
In recent weeks a private and quite unofficial survey has been taking place in certain districts within the London County with a view to suggesting improvements in side road lighting. The Report, unfortunately, contains some disappointing information. Too many side roads appear to be black holes with an odd lamp placed here and there.
Main road lighting is indeed worthy of highest praise, and a credit to both the Lighting Engineer and the lamp and lantern manufacturers.
In the survey, it was felt that gas lighting in many cases was a distinct improvement over electric lighting. The low mounted gas lamps, with the pleasing and soft-coloured light, appeared to give out a wider spread of even light, in constrast to the sharp light from the filament electric lamp. In the latter case the brightness of the source of light "killed" the spread of light on the road - and in cases where a particular type of reflector was installed, shafts of glare appear which is most discomforting for the road user.
Side road lighting needs a good overhaul - it's in this direction where one solution can be found for road safety.
Lighting: Theory

Accident Statistics p106
Accident statistics issued by the Ministry of War Transport show a reduction in deaths on the road as compared with the same month the previous year. For July 1945, there were less accidents in the month of partial lighting of "Black out" (1945) than in the same month of "Black out" (1944). From this fact it may be claimed and proved that lighted roads do reduce accidents.
Statistics: Accident Data, Lighting: Safety

Wilful Damage to Street Lamps p106
Representation has been made to the Home Secretary and he has undertaken to bring the matter to the notice of Chief Constables throughout the country. It is hoped that by bringing this matter to the notice of the public and seeking their co-operation will overcome this menace.
Lighting: Anti-Social Behaviour

Extraneous Lighting Near to Airports p106
Attention is drawn to the Memorandum issued by the Director of Civil Aviation appealing to public lighting engineers to take appropiate action to prevent street lighting from confusing air crews when approaching an airfield to land. The same caution is also directed to road traffic control signal lights. (Some of the text appeared in the previous issue). The Association should also consider the feasibility of the introduction of bye-laws controlling the erection and operation of illuminated signs.
The issue of illuminated signs has exercised Authorities throughout the country. It should never be permitted for illuminated advertising signs to be erected on the frontage of any building unless approved by the appropriate official appointed by the Council.
Lighting: Specifications

What Does This Mean? p106
Mr. R. G. Strauss, Parliamentary Secretary to the Ministry of War Tranport, in replying to the debate in the House of Commons on the Trunk Road Bill is reported to have said concerning the public lighting on main roads: "The Minister will go into this question as soon as possible, with the other Government departmetns concerned, with a view to devising a better system." The complaint had been that the Ministry, having taken over control of certain trunk roads, had refrained from taking any responsibiltiy for the lighting of such roads. However, it turns out that the Minister was refering to the financial responsibility for lighting the roads.
Lighting: Funding, Lighting: Legal

Lighting Of Bends And Junctions by Francis F. Middleton p107
A full reporduction of Middleton's paper is included.

Mr. F. C. Smith (Gas Light And Coke Company): The author had successfully drawn attention to the importance of backgrounds. Whilst in wholehearted agreement, he felt that the paper so simplified the problem that it might be misleading. The situation presented was too static and backgrounds were not so clear-cut.
Mr. V. Hewitt (Rawtenstall): Criticised the reading of papers in full. Suggested only summaries should be read. (The President said the council would bear that in mind for the future).
Alderman F. Thraves (Sheffield): The reason most delegates attended Conferences was to take back to their Committees and Councils information. A paper of this kind was so high technical that it presented a mist of information which was difficult to sort out. There were two types of mind on all Committees: one so dererential to the technical man that no one question him; the other that was not convinced by anything. The paper was excellent and he understood more after the presentation. Still, his mind was a muddle and he did not know how to convince his Committee. (Incidentally, to see a well lighting city go to Sheffield!)
Mr. E. L. Leeming (Lighting Engineer, Urmiston): There were many badly designed bends in this country and the lighting would be much improved if it was super-elevated instead of cambere - in that case the lighting would be better on the inside of the bend. More economical lighting might be obtained with more uniform distriubtion if a greater use was made of super-elevation. Junctions could be lit with a different colour light - this would assist road safety. Most roundabouts were also badly designed; they were too small and the slope of the road was in the wrong direction. It should be inwards and this would permit the use of low level lighting on the inside of the bend instead of high level lighting on the outside.
Mr. R. Greaves (Lighting Engineer, St. Helens): Disagreed with low mounting heights on the inside of bends. High level lighting could be seen at a distance and enabled the traffic to get round bends better. Electric lamps had to be put up high because there was glare from them, but gas did not need to go so high because there was no glare. A height of 18' was ideal for gas and the 25' high electric lamps were placed so far apart that there was no comparison. Many lighting engineers could show exmples of the lightign of bends with two lower power low-mounted gs lanterns which gave much better results than high mounted electric lamps which produced hare.
Mr. E. C. Lennox (North-Eastern Electric Supply Co.): Discussion should be kept within the limits of the paper. The author had talked about background brightness not roadway brightness. Did the author know of any firms producing lanterns purely for roadway brightness? Personally he did not know of any firms that were doing that. In the lighting world, everyone was convinced there must be background brightness.
Mr. Middleton: Where the brightness varied, the installation was badly designed. Different coloured lights could cause eye strain due to eye adaptation. Super-elevation of the road surface would not be necessary if there was good background lighting so that pedestrians could be seen on the pavement.
Lighting: Distribution, Lighting: Theory

A Post-War Course In Illumination And Public Lighting p112
A special class has started at Stow College School of Engineering by Mr. F. M. Hale, B.Sc. of the Lighting Department, Glasgow. The course covers the syllabus for the Intermediate Examination of the City and Guilds of London Examination. It includes:
1. Light Production and Control
2. The Eye and Vision
3. Photometry
4. Practical Light Sources
5. Illumination
6. Distribution and Control System
Lighting: Education

Royal Society For The Prevention Of Accidents p112
Mr. R. G. Strauss, the Parliamentary Secretary to the Ministry of War Transport, addressed the Public Safety Committee. He made special reference to the forthcoming Road Safety Campaign and he referred to the 4,459 miles of trunk roads taken over from local authorities under the Trunk Roads Act 1936, stating that a further 3,700 miles of roadways would be taken over from the County Boroughs and County Councils upon the passing of the Trunk Roads Bill now before Parliament. Under the final approval of this Act, no less than 8,150 miles of trunk road will be under Government control. The question of improved street lighting was also referred to.
Lighting: Authority Organisation, Lighting: Legal

The Lighting Of Albion Street, Southwick, Sussex p113
Details of the the installation and how it conforms with the proposed B.S.I. Specification.
Lighting: Installations, Lighting: Specifications

Official Advertisement p113
Advert for the appointment of a Public Lighting Assistance for the Corporation Of Greenock.
Lighting: Management

The Relation Of Public Lighting Safety On The Roads by Norman Axford, B.Sc., A.M.I.E.E. p114
The total number killed on the roads during the five years of war was 38,970 - an average of 21 killed every day. How can we, as Public Lighting Engineers, do our part in assisting to reduce this terrible and possibly increasing casualty list?

1. What part does faulty public-lighting play in the causation of street accidents?
The analysis of the cause of a street accident is a complicated affair. Unfortunately statistics are not kept where street lighting is named as the major cause of the accident.

What is the relation of night casualties to day?
From a special analysis of fatal road accidents during the period April 1936 to March 1937 made by the Ministry of Transport the results were: Daylight 62%, Dark 38%. Figures were kept during the war years and the Road Accident Bulletin No. 18 published by the Royal Society for the Prevention of Accidents: this shows the average number of deaths per day on the roads year by year from 1937 to 1944, and separated between daylight and after dark during the war years. As would be expected, during the first year of blackout, the average after dark rose from 38% to 54%. In succeeding years, the figures fell to 43%, 39%, 36% and finally 32%. This is largely due to less traffic after dark as the years went by, and the small amount of "Starlight" lighting would've contributed.
Other data came from the London Metropolitan Police Authorities, and shows the time of traffic accidents (a) on 260 days, Monday to Fridays, and (b) 52 Saturdays and Sundays, all for 1938. On weekdays and Saturdays, the peak accident times coincide with the peak rush hours, but on Sundays the maximum figure occurs well after dark.
It would seem that we might reasonably expect something of the order of 40% of road accidents to occur after dark in this county if pre-war conditions of lighting and traffic density continue.

What is the effect of improved street lighting?
There is no doubt that improved street lighting reduces the night accident rate, but there are so many factors involved in any accident that to study it scientifically, I suggest it would be of great advantage to the Public Lighting industry, if a section of a city or length of roadway could be taken, where it is known that the present system of lighting is not good, and it is intended to carry out improvements in the fairly near future, for an accurate scientific survey to be undertaken both before and after the improvement. If such a scheme is to be put into effect then the following items must be included on the accident report form:

(1)Time of Accident and weather conditions
The survey should be for twelve months either side of the date of improvement, so that comparisons of the accident under all conditions likely to be found throughtout the year can be made.

(2) An endeavour should be made to assess blame on either driver or pedestrian
This would enable one to judge whether lighting should be increased in value near places where large numbers of people are likely to be found.

(3) A Traffic Census must be taken during the period of test.
Consideration must be given to the respective volumes of traffic flowing. It should be sufficient to take figures for a week, say six times a year, as fairly representative.

(4) Rough Estimate of cost of damage caused
Allows the cost of improved Public Lighting to be compared with the cost of accidents occuring prior to its installation.

(5) Site plan of accident to include position of street lamps if accidents after dark
This will assist in deciding whether some re-siting is necessary if it were found that accidents were always occurring under certain similar conditions.

(6) Speed of vehicles concerned
This would counter the argument that improved lighting invites higher speeds and hence more accidents.
In Detroit, night-to-day fatalities from 2.4 to 1 fell to 1.4 to 1 by installing an improved lighting system, with the illumination increased 4 to 6 times its previous value. Safety lighting installed on more than twelve miles of Syracuse Main Traffic arteries resulted in a night accident reduction of 24.9% over six to eight months. In Hartford, Connecticut, the night-to-day accident ratio was reduced from 57% to 38%. London Embankment figures also given. Generally it can be accepted that improved street lighting will go a long way to reduce the after dark casualties.

4. What particular points must be borne in mind in designing a street-lighting layout.
A well planned installation should :-
(a) Reveal objects in the path of vehicles within the limit of the driver's abiliy to take appropiate action and stop if necessary.
(b) Reveal persons on the footpath clearly so that the driver can have some intimation of their probable future action.
(c) Indicate clearly side roads and danger points.
(d) Give these results under varying weather conditions.
The functions of modern street lighting may be summarised as: 1. For the safety of road users; 2. For police purposes; 3. For the convenience of residents; 4. For emphasising some particular area i.e. a civic centre.

The MOT recommended two classes of lighting: Group A for main traffic routes; Group B for other roads.

Main Traffic Routes
The lighting of these should be such that there is adequate safety for all road users without headlights being used. This means driving at 30m.p.h withotu headlights the driver must be able to see the road ahead clearly and be able to define any object on it in sufficient time to avoid it at that speed.

Objects are generally seen as dark against a light background. The well-designed layout should provide a bright road surface so that the objects on it appear in silhouette. The brightness of the road is obtained by placing the light sources in such a position that the light is reflected at a very oblique angle and the patches of reflected light from each unit merge together. The siting and design of lanterns must be such that glare is the driver's eyes is reduced to a minimum.

The road surface is not the only background against which objects will be seen, particularly on bends. Therefore street lighting should also ensure that footpaths, buildings, fences etc. adjacent to the roadway appear light in colour so pedestrians about to cross the roadway can be spotted. This is sometimes difficult to obtain in practice and can be overcome by using white or chequered boards.

On bends, it follos that to obtain the patch of reflected light, the light sources must be placed on the outside of the curve. Getting the patches to merge uniformally is part of the Public Lighting Engineer's art.

Where thoroughfares have heavy foliage lining them, it may be difficult to adopt side mounting of the light sources, and it may be necessary to adopt central suspension.

Other roads
Because of the lower traffic density these do not present so much danger as the main traffic routes. The same general principles remain. Too often when residential housing estates are laid out, street lamps are placed haphazardly along the roads, resulting in patches of light and darkness, a frequent cause of accidents.

The lighting will fall off rapidly unless a regular cleaning and maintenance programme is maintained. I would stress the advantage of changing all lamps on a regular routine when they have completed their guaranteed life. This maintains the standard of lighting but reduces "Outs" which may be the cause of accidents.

Cost of Installation
In Hartford, Connecticut, records of the costs of accidents were kept. It was shown that an increase of 8425 dollars per annum in street lighting resulted in a decrease of 36550 dollars in the cost of accident damage. For human lives, it is not possible to put a value on these, but six people were killed after dark every day last year in the UK, around 2000 deaths per year. If improved street lighting were able to reduce this by only 50%, would it not be worth while spending what is, a very small sum, to say that at the end of the year 1000 people are alive today who might otherwise be dead?

In order to give some idea of the actual cost of a properly laid out installation in a town of 200,000 inhabitants, the following approximate figures may be of interest. The town has 23 miles of main traffic routes and 200 of 'otherroads'. To attain the standard of illumination laid down in the Final Report of the MOT, I have assumed (a) on the main roads, 250W mercury lighting at 150' spacing; and (b) 100W metal filament lamps at 120' spacing. If costs were about 30% above pre-war, the approximate costs would be: (a) main traffic routes £12,350 per annum; and (b) other roads £55,675 per annum. I have assumed all-night running. The total figure may appear on the high side, but the result would be a public lighting installation of which the town would be proud and would certainly bring about a marked drop in after dark accidents.
Reusing solumns on side roads a saving of £2,500 per annum could be made. It might be possible to extend the spacing a little along the other roads, saving a further £6,500 per annum. This would bring the final total to £46,675 per annum or just under 5s per annum per head of population Surely this could be afforded?
In 1939, when faced with the possibility of death and injury from air raids, approximately a third of a million pounds were used as capital expenditure only to save life as far as possible. It doesn't seem possible to do this in peace time, but surely we should be prepared to spend £100,000 to save life?

1. There is no doubt that a properly planned street lighting installation will result in an appreciable decrease in night traffic risk.
2. That it would be well worthwhile carrying out properly conducted tests to investigate the actual relationship of street lighting to accidents.
3. That although correct lighting costs money, its installation will result in saving to the community as a whole.
Lighting: Funding, Lighting: Safety, Lighting: Statistics, Lighting: Theory, Statistics: Accident Data

Street Lighting Control: A Description Of The "Record" Control System p119
System devised after careful consideration of the advantages claimed by several existing systems. The greatest advantage claimed is that no additional wiring is required. In many districts, pilot wires are already in existence, while where new cables are being laid the cost of the extra core is almost negligible. Therefore they developed a scheme which would be simple in optionation, and therefore cheap, and would use the pilot wire to transmit impulses so would be free from external interference.
The outcome was the "Record" Remote operated Selective Switching Unit. It does not depend on an operating current which is different in frequency or voltage from that alreadying existing on the L.T. network, which overcomes the trouble of maintenance, since it does not require technical knowledge outside the sphere of lighting.
It depends on its operation purely upon an impulse of approximately 5 seconds along the pilot wire, the potential being any existing L.T. phase voltage at normal frequency or D.C.

The Transmission Of Impulses
The simplest form of impulse transmitter is an ordinary push button connecting phase to pilot and operated by hand to switch "on" and "off" the whole of the lighting. This suffers from the disadvantage that there is no visual indication of the lighting position and relies on the human element for its operation at any time. This is overcome by housing in one box the appropriate number of receiving units with control lights, which indicate the lighting position at any time. In addition, there is a time switch which times the impulses to suit the requirements. A push button is provided for use in emergencies, such as fog conditions etc.

The Receiving Unit
This is a solenoid operated switch which has been designed to have its contacts open or closed in any predetermined sequence with a maximum cycle of eight different positions, after which the cycle is repeated. This cycle is brought about by the solenoid plunger operating an eight-toothed lantern pinion which carries a cam, which in turn opens or closes the contacts, according to the shape of its periphery. Therefore by fitting different shapes of cam, any combination of lighting can be arranged to suit up to eight different conditions. This can be used both to accommodate partial switching off for skeleton lighting after midnight, and for gradual switching on, so that the full lighting load is not suddenly switched on without warning. The contacts of the switches are of pure silver and there is considerable pressure between the contact faces when they are closed. A pair of contacts would stand several hundred thousand operations while controlling a load of 400 watts without undue burning. There is also a patented mechanism coupling the pawl on the solenoid plunger to the lantern pinion, or rotor, which prevents the latter from overshooting. This makes it possible to put plenty of reserve power into the solenoid without fear of its momentum carrying the rotor round too far. A switch wound to operate off 230 volts, 50 periods, will still operate on a voltage as low as 160. Also, as part of the mechanism is a non-return pawl on the rotor to prevent it for either move round and getting out of position due to vibration, or being pushed in the reverse direction due to pressure from the contacts. The contact operating cam is easily changed at any time if a different programme of lighting is required. The whole is housed in a neat brass cover which is designed to overcome open-air conditions.

Operation on Non-Pilot Schemes
The system can be operated on a two-wire system. The limitations are (i) the two wires must be for lighting distributions i.e., not general service mains and (ii) that the operation of the scheme depends upon a momentary interruption of the circuit, it cannot be used to give suitable control of mercury vapour lamps. Discrimination of lighting is acheived by breaking the supply to the two wires, which allows the solenoid plungers to fall, and then quickly restore the supply which energises the solenoid, thus turning the cam around to the next position. The break in the two-wire circuit can still be initiated from the central control point by an impulse.
Lighting: Control

London Street Lights To Stay p121
London boroughs rejected for reasons of public safety and security the recent appeal from the Ministry of Fuel to switch off street lighting at midnight. Every London road will be lit throughout the winter nights; main roads will be well lighted and side streets partially lit. At the same time, borough councils will co-operate with the Ministry to drive to conserve coal by maintaining street lighting at half the pre-war standard. An official of the Ministry of Fuel said: "Our object was to bring about that economy by cutting down consumption. Our objective will have been achieved.
Lighting: Energy

The Appointment Of A Public Lighting Engineer p121
The Public Lighting Engineer is now a recognised professional official and several of the chief cities in this country have appointed such men to take over full control of all street lighting within the cities' boundaries. The work involved in planning a modern street lighting installation requires the services of an expert. Whilst such services are available from the manufacturers - it must be agreed that the lighting authority is invariable left to the mercy of such advisers, who view every lighting installation with a commercial bias. There is little doubt that in these post-war years when street lighting becomes still more advanced, and when new lighting equipment becomes available, and still brighter lamps are put on the market, the services of a qualified public lighting engineer of the type as already indicated will become a real neceesity and will be in great demand.
Lighting: Management

Clockwork Controllers: Repairs p121
Textural advert for J. W. and R. E. Hughes (Clockwork Engineers)

A Stair-Lighting Threat p121
Street lighting officials in Greenock have threatened to cut off all stair lighting unless the vandalism of gas mantles ceases at once. In preparation for the winter, stairhead lamps were overhauled. Now hundreds of the mantles have been destroyed. A greet deal fo the damage has been done by people lighting cigarettes or pieces of paper from the mantles.
Lighting: Anti-Social Behaviour

War Loss And Patents p122
Report on changes to war damage applications and extention of patent terms under Section 18 (6).

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