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ilp archive : london 1946


Annual Conference at London
Central Hall, Westminster, W.C.1
September 10th-12th, 1946

In the year of Victory it was considered appropriate that the Conference should be again staged in the Capital.

No less than thirty-eight prominent manufacturing firms specialising in street lighting equipment will be displaying their products.

Three-quarters of the forty displays are of wholly or mainly electrical interest. The growing ppularity of electrical discharge lighting is also very noticeable.

Planned exhibitors and stand numbers were: (1) The Electric Street Lighting Apparatus Co., (2) Foster And Pullen Ltd., (3) The Horstmann Gear Co., Ltd., (4) Metropolitan Vickers Electrical Co., Ltd., (5) Gas Meter Company Ltd., (6) Record Electrical Co. Ltd., (7) William Edgar & Son Ltd., (8) Broad & Co. Ltd., (9) W. Parkinson and Co., (10) Lighting Trades Ltd. and the Welsbach Light Co., Ltd., (11) Gowshalls Ltd. (using Radiovisor Parent Ltd. lighting controls), (12) Elm Works Ltd., (13) British Foreign and Colonial Automatic Light Controlling Co. Ltd., (14) Willey And Co., Ltd., (15) Stanton Ironworks Co., Ltd., (16) William Sugg And Co., Ltd., (17) British Gas Council, (18) The Brighton Lighting And Electrical Engineering Company, Ltd., (19) REVO Electric Co., Ltd., (20) Holophane, Limited, (21) Stewarts And Lloyds, Ltd., (22) Philips Lamps, Ltd., (23) Engineering And Lighting Equipment Co., Ltd., (24) The Association Of Metal Sprayers, (25) Standard Telephones And Cables Ltd., (26) Poles Ltd, (28) Falk, Stadelmann and Co. Ltd., (29) British Sangamo Co. Ltd., (30) Edison Swan Electric Co. Ltd., (31) Spun Concrete Ltd., (32) Concrete Utilities Ltd., (33) British Electrical Development Association, (34) Automatic Telephone And Electric Company Ltd., (35) Siemens Electric Lamps And Supplies Ltd., (36) The General Electric Co., Ltd., (37) Measurement Ltd., (38) The British Thomson-Houston Co. Ltd. and (39) Venner Time Switches Ltd.

Abstract: Descriptions of lanterns and equipment displayed by The Electric Street Lighting Apparatus Co., Foster And Pullen Ltd., The Horstmann Gear Co., Ltd., Metropolitan Vickers Electrical Co., Ltd., Gas Meter Company Ltd., Record Electrical Co. Ltd., William Edgar & Son Ltd., Broad & Co. Ltd., W. Parkinson and Co., Lighting Trades Ltd. and the Welsbach Light Co., Ltd., Gowshalls Ltd., Radiovisor Parent Ltd., Elm Works Ltd., British Foreign and Colonial Automatic Light Controlling Co. Ltd., Willey And Co., Ltd., Stanton Ironworks Co., Ltd., William Sugg And Co., Ltd., British Gas Council, The Brighton Lighting And Electrical Engineering Company, Ltd., REVO Electric Co., Ltd., Holophane, Limited, Stewarts And Lloyds, Ltd., Philips Lamps, Ltd., Automatic Telephone And Electric Company Limited, Engineering And Lighting Equipment Co., Ltd., The Association Of Metal Sprayers, Standard Telephones And Cables Ltd., Poles Ltd, Falk, Stadelmann and Co. Ltd., British Sangamo Co. Ltd., Edison Swan Electric Co. Ltd., Spun Concrete Ltd., Concrete Utilities Ltd., British Electrical Development Association, Siemens Electric Lamps And Supplies Ltd., The General Electric Co., Ltd, Measurement Ltd., The British Thomson-Houston Co. Ltd., Venner Time Switches Ltd. and Londex Ltd.

Adverts: Radiovisor Parent Ltd., The Electric Street Lighting Apparatus Co., Foster And Pullen Ltd., The Horstmann Gear Co., Ltd., The Horstmann Gear Co., Ltd., Metropolitan Vickers Electrical Co., Ltd., Gas Meter Company Ltd., Record Electrical Co. Ltd., William Edgar & Son Ltd., Broad & Co. Ltd., W. Parkinson and Co., Wardle Engineering Co. Ltd., Lighting Trades Ltd. and the Welsbach Light Co., Ltd., Gowshalls Ltd., E. K. Cole. Ltd., Elm Works Ltd., Automatic Light Controlling Co. Ltd., Willey And Co., Ltd., Philips Lamps, Ltd., William Sugg And Co., Ltd., British Gas Council, The Brighton Lighting And Electrical Engineering Company, Ltd., REVO Electric Co., Ltd., Holophane, Ltd., Stewarts And Lloyds, Ltd., Automatic Telephone And Electric Company Limited, Engineering And Lighting Equipment Co., Ltd., The Association Of Metal Sprayers, Standard Telephones And Cables Ltd., Poles Ltd, Poles Ltd, Falk, Stadelmann and Co. Ltd., Hobbs Offen And Co. Ltd., British Sangamo Co. Ltd., Edison Swan Electric Co. Ltd., Spun Concrete Ltd., British Electrical Development Association, Crompton Parkinson Ltd., The General Electric Co., Ltd, The British Thomson-Houston Co. Ltd., Measurement Ltd., Venner Time Switches Ltd., Londex Ltd. and The General Electric Co., Ltd.

Provisional papers (as planned in Public Lighting #41):

Presidential Address by Mr. W. N. C. Clinch, M.I.E.E.
Would Public Lighting Achieve Any Advantage If Some Form Of Administrative Central Control Were Indicated by Mr E. C. Lennox, M.I.E.E.
The Organisation And Control Of A Public Lighting Department by Mr. Ronald Parker
Street Lighting From The Motorist's Point Of View by Mr. Edward Fryer, Secretary of the Automobile Association
A paper dealing with Gas Street Lighting by Mr. Crawford Sugg
A technical paper and demonstration by a research officer from the electrical industry.

1000 delegates attended from 533 local authorities.

Presidential Address

Mr. W. N. C. Clinch, M.I.E.E.
The Northmet Power Company

Tuesday, September 10th, 1946

A copy of the paper was included in : Public Lighting, Vol. 11, No. 42. July-September 1946. Unfortunately the the copy in the archive has gone missing.

Public Lighting - Administration

Mr. E. C. Lennox, M.I.E.E.

Keywords: Lighting: Authority Organisation, Lighting: Legal

Wednesday, September 11th, 1946

A reproduction of the paper was published in: Public Lighting, Vol. 11, No. 42. July-September 1946. This includes the discussion.

Abstract: Is some form of "Central Control" of public lighting beneficial to the community? This paper studies the pros and cons.

The present administration dates from the Lighting and Watching Act of 1833 which has been amended from time to time by the various Local Government Acts. "Street lighting is permissive - the decision as to whether or not to provide lighting rests with the Lighting Authority, who can adopt any standard of lighting, any season of lighting and any times of lighting and extinguishing. Street lighting is parochial - both in regard to the extent of roadways lighted and to the area for the collection of monies necessary for its provision and upkeep.

1. General
The rich City or Country Borough has merely to find the money necessary to deal with the lighting of streets and rodways within the boundaries of its administrative area and there is no great financial burden. The work is undertaken by a special Public Lighting Department under the guidance of skilled Lighting Engineers and staff. There is often attached to the Department a fully equipped laboratory to carry out the testing of lamps and equipment used in connection with their work.

The smaller administrative areas, especially the smaller urban districts and rural parishes, find great difficulty in raising sufficient monies to undertake even inadequate lighting schemes. The lighting of small areas are ofthen under the guidance of the District Surveyor, or in the case of Parishes, by the Clerk to the Council, who wisely leaves the type and maintenance of the lighting scheme to the local electricity or gas undertaking.

It is only natural that such a "parochial" outlook should result in an inefficient system of lighting to the road-user in general. Such inefficiency arises from:

  • (a) Lack of uniformity of standard lighting on continuous lengths of roadway.
  • (b) Lack of co-ordination between adjacent Lighting Authorities.
  • (c) Various times of lighting and extinguishing.
  • (d) Lack of compulsion to provide lighting - vital places are often unlighted.
Not only has the public the right to expect adequate lighting on traffic routes in built-up areas in rural parishes and urban districts, but the ratepayers in such districts have the right to expect the richer towns and cities to assist in paying for such lighting.

2. Recommendation of M.O.T. Street Lighting Report, 1937
This brought out the need for:

  • Reasonable uniformity of the lighting of portions of traffic routes which present similar characteristics.
  • Consideration to be given to the responsibiltiy for lighting traffic routes being confined to large administrative units.
  • Aids by grants from national funds, administered by the responsible Government Department.
  • Adjoining authorities to confer with the object of securing uniformity of lighting on routes of common interest.
  • Lighting Authorities to be advised by competent Engineers as to how to deal with street lighting.
3. Financial Considerations
The lighting costs of a traffic route varies from 3d./6d. in the richer areas to 1s. 3d. in the smaller-rated parishes. Supposing the authorities did co-operate and met the cost in proportion to the rateable value, then the cost per pound of rateable value would average less than 1d.

1. Road Traffic Act, 1934
Section 23 of this Act allows the Council of the County to assist in the lighting of a county roadway "provided that there shall be no derogation of the powers of the existing Lighting Authority." All expenses incurred by the Council of the County under this section "shall be expenses for general county purposes" but this is subject to a proviso which means that any Lighting Authority who already light any county roads at their own expense need not pay towards the lighting of the county road chosen by the County Council. As a result, every Lighting Authority attempts to light in a relatively small way some part of a county road in their area, the County Council are left to gather the additional rate for better lighting of the chosen road from merely the Lighting Authority in whose area the road is situated, assisted only by the rates from those few areas which have so far not adopted the Lighting and Watching Act and heave, therefore, previously no lightign rate but whose rateable value is neglible. Such a clause defeats itself and has not been carried into effect. An alternative could be that the County Council, with the consent of all Lighting Authorities in the County, could become the means of paying for the lighting of all County Roads in the County area. Such a method would result in a fairer average rate for lighting the County roads but even so the the total lighting rate in County ares would be higher than that existing in the larger and relatively richer towns and cities.

2. Trunk Roads Act, 1936
Section 6(4) of this Act is one of clearer understanding and capable of easy application. Under this clause the Minister of Transport takes power for the entering into and carrying into effect of Agreements with Electricity or Gas Undertakings for the provision of equipment for lighting of Trunk Roads. The initiative to proceed has come from a Parish or Urban Authority for that part of the trunk road and grants, generally up to 50%, have been made in several cases. An important condition of obtaining a grant is the necessary approval of the lighting scheme by representatives of the Ministry Of Transport, thus ensuring the lighting is in accordance with the MOT Report 1937. This lessens the burden of the Lighting Authority but applies to only some 8000 miles of traffic route, the majority of which is in open country and not likely to require lighting. Moreover, the remaining burden of 50% of the cost is often too much to be made out of the local rates.

It is suggested t he time is opportune for some form of central administration, particularly given the following:

  • (1) The amount of traffic is increasing daily and in a few years will exceed the pre-war figures.
  • (2) The accident rate during dark hours will rise with the increased traffic.
  • (3) The present method of rating for street lighting has failed to produce adequate and uniform lighting on through traffic routes and built-up areas.
  • (4) Revenue for provision of lighting should not be a parochial matter.

A central form of Administration would be expected to result in:

  • (1) An evening of the burden of cost.
  • (2) A greatly improved general illumination of streets and roadways and a uniform and appropriate standard on traffic routes.
  • (3) Some form of control by a central body to ensure provision of only approved lighting schemes and their adequate maintenance.

How would such an administration be undertaken? One method would be to apply to the provision and maintenance of lighting on roads the same practice as is carried out in respect to the provision and maintenance of the roads themselves. The burden of the cost of lighting would then become a matter of payment from national funds for the trunk roads, County or County Borough funds for the next most important roads and parochial funds for the least important roads, the provision and maintenance of lighting being subject to the same grants as are now made by the Ministry of Transport in connection with road maintenance.

The objection which could be raised against this proposal is that the richer counties (cities) would find the cost of lighting a much less burden than that of the more rural administrative unit. An alternative procedure would be to obtain grants from a national source for the lighting of the administrative area. Surely no better fund exists than direct taxation of motor vehicles called "The Road Fund" - to be administered for the construction and maintenance of adequate roads to meet the increasing traffic conditions. It is presumed that grants from national funds would not be allowed without some measure of control ensuring proper advice in connection with the individual schemes.

The benefits would be:

  • (4) A standardising in terms for supply of energy throughout the Country.
  • (5) A considerable saving in road accidents.
  • (6) The additional cost of safety lighting above that now provided would be but a small insurance premium, which by a reduction in the accident rate, will eventually reduce the premium for the insurance of motor vehicles.
  • (7) Assistance to the police and crime prevention.
  • (8) The encouragement of regional testing centres, in the charge of competent Lighting Engineers, who would give advice to all Lighting Authorities in that region.

Only by following some such method of raising funds nationally for the purpose of providing appropriate lighting will the present most unsatisfactory position in regard to the lighting of our traffic routes be corrected.

The Public Lighting Engineer
His Organisation, Staff and Training, with Postscript to Councillors

Mr. Ronald Parker

Keywords: Lighting: Authority Organisation, Lighting: Education, Lighting: Funding, Lighting: Maintenance, Lighting: Management

Wednesday, September 11th, 1946

A reproduction of the paper, and the discussion, was published in: Public Lighting, Vol. 11, No. 42. July-September 1946

Abstract: Description of an idealised lighting department with breakdowns of all the key personel involved. Also gives suggestions how smaller lighting authorities could use the resources of larger ones in co-operative relationships.

Previous papers on this subject have been concerned with a particular lighting department.


The whole department will be under control of the Public Lighting Engineer. He has final responsibility and be answerable to no one but the Committee of his Local Authority. He shall have no duties other than those directly related to street lighting. He will be assisted by:

  • A technical section.
  • A workshops section.
  • A lamp lighting and cleaning section.
  • An administrative section.

The Technical Section

  • To operate a properly equipped photometric laboratory
  • To sssist the Lighting Engineer in the planning of schemes
  • To supervise the Workshop Staff in the installation of schemes
  • Perform street tests
  • Study all complaints received relating to faults in connection with illumination, mechanical and electrical defects. Suggest steps for the prevention of any defects.
  • To conduct routine tests of materials purchased.
  • To examine new designs of apparatus submitted by manufacturers.
  • To examine and try out new ideas for the applications of light to the streets.

The Workshops Section

  • Install all new lighting apparatus.
  • Keep all lighting apparatus in sound condition mechanically and electrically.
The Lamp Lighting and Cleaning Section
  • To see that the street lights are lit and extinguished timeeously. If there is central control, they may be restricted to the criticism of operating times.
  • To see that all lamps give their full light at all appropriate times.
  • To keep glassware and fittings clean.
  • To replace electric lamps, discharge tubes, gas mantles and nozzles as required.

The Administrative Section

  • To conduct correspondence
  • To keep personnel records
  • To keep financial records including cost accounts
  • To keep, compile and present statistics of all kinds
  • To arrange for supplies of materials
  • To supervise the keeping and issue of stores.

Scheme For Detailed Organisation Of Lamp Lighting And Cleaning
Fundamental requirements of the scheme are: (i) Each man will be given a fixed territory of operation; (ii) He shall not be required to leave his territory during working hours; (iii) Ladders shall be placed at strategic positions; (iv) Each man keeps his small tools and stores at his home. Each man has evening duties and morning duties.

Evening Duties: There must be a nightly tour covering the whole of the lamps in the territory. Faults will be dealt with as follows: (i) If on low-mounted units, they will be fixed if possible. If a fix isn't possible then it's reported for early attention by the Workshops Section; (ii) If on high-mounted units they will be reported to a special Standby Squad having the necessary equipment. Main roads should be checked first so the Stanby Squad have early notice. Where lighting and extinguishing is by mechanical means, it is wise also to so arrange the tour so that lamps are under review some little time before lighting.

Morning Duties: Each man is responsible for the cleaning of glassware, reflecting surfaces of all the low-mounted lamps on his territory.

Each day a man will spend two hours on Evening Work (7 days per week) and five hours on Morning Work (6 days per week).

The Standby Squad will have duties similar to the lamp lighter and cleaner. They do not do a tour of inspection but will be on standby at the depot, followed by a period during which reported faults will be put right. The morning duty will be devoted to cleaning.

Supervision Of Lamp Lighting Staff
If the inspection staff consists of intelligent and well-trained men, any abuses of the system will quickly be detected and suitable countermeasures will be devised. Each man should be inspected at his work durign cleaning operations. A report should be received daily from the lamp lighter of work done. In checking evening work, checks should be imposed to ascertain that men turn out for their work timeously. Inspection staff will keep a close eye on the setting of redirective apparatus, and will note failures on the part of the Workshops Section to give early attention to reported faults.


The advocates of regionalisation have been pointing out for some years the impossible financial burden which would be imposed upon many small lighting authorities if they were caleld upon to light all their roads to modern standards, and have advocated larger lighting areas so that burden might be spread. The proponents of regionalisation have based their arguments very largely upon the lighting of traffic routes. But so much concentration on the problems of the traffic route has thrown it out of its true perspective - it is only a small portion of the total public lighting under the control of small lighting authorities.

It appears to me that regionalisation does not appear in the main to local authorities nor to Central Government and any alterations which may be made to the general structure of public lighting arrangements and responsibilities in the next decade will be of a minor nature only. A few large undertakings have given the matter serious consideration and give a first-class street lighting service to those lighting authorities in contract with them. But such undertakings cover a relatively small area of the whole country and elsewhere the standards achieved, particularly of maintenance, are poor. Then there are the authorities who put out installations to tender, but undertake their own maintenance: it is not difficult to obtain expert advice, apparently free of cost, by inviting suppliers to submit tenders. But it is impossible to make any satisfactory choice without independent technical advice. For the smallest authorities, contracting with an electricity or gas undertaking is the best method. But how will technical supervision which normally rests with the public lighting engineer and the technical section may be obtained?

In the case of a number of small lighting authorities grouped around a large, or fairly large one, the total public lighting in such an area, operated as one unit, would warrant the employment of a public lighting engineer and technical section: this would be called the Technical Service. It is essential that each authority shall contribute to its installation and upkeep, and shall be entitled to a service upon an agreed basis. The duties of the Service would be to give technical advice upon all new or remodelled installations, planning them in detail, and drawing up specifications if tenders are to be sought; and to ensure that in all authorities the highest possible standard of maintenance is attained at all times, by means of constant technical supervision.

This arrangement is a voluntary one and can only arise out the desire of the small lighting authorities to get the best they can afford.


Public Lighting Engineer
(i) Executive and Administrative Ability: A gift, but one which can be improved by training and experience.
(ii) Technical Ability: Combination of theoretical knowledge and the ability to apply it in practice. If public lighting engineering is to become recognised as a profession nationally, it is very necessary that the training of persons entering it shall be systematic both in theory and practice, and that there shall be attainabel at the end of training some nationally recognised status.

The outline of training, course lengths, syllabus and diplomas is then proposed at length.

The Deputy Public Lighting Engineer
Normally the department's size doesn't support such an appointment. However, this is essential as a training position.

The Technical Section
This will be under the Deputy Public Lighting Engineer or the senior trainee. His minimum staff will be the laboratory assistant and a junior trainee (usually straight from school and studying Illuminating Engineering).

The Workshops Section
Will have to be staffed by qualified tradesmen of various kinds together with their associated labourers. The General Foreman will have varying qualifications depending on whether the emphasis is on gas or electricity.

The Lighting and Cleaning Section
The Inspection Staff: Qualifications required are ability to handle men with tact and understanding, the pocession of an alert mind able to absorb technical knowledge, and will have served as a lamp lighter for at least a few months. There should be one inspector per twelve lighters and cleaners. In charge of the inspectors will be a Senior Inspector.

The Lamp Lighting and Cleaning Staff: Men who are careful and reasonably intelligent must be selected. He must be able to carry out his duties conscientiously with a minimum of supervision.

The Administrative Section
The Chief Clerk will be in charge. There will be two general clerks, an expert typist and stenographer, and a junior clerk.

Postscript To Councillors
You are not directly concerned with the detailed organisation of lighting departments, but in the long run the efficiency of such departments, and, through them, of your street lighting is determined by the decisions you make when reviewing the arrangements for the control of your street lighting and in appointing officials to have charge of it.

How is the competent public lighting engineer to be recognised? There is at present no hall-mark of the fully-trained public lighting engineer. It arised partly from the extreme youth of the science of street lighting and its emergenc as a profession comparatively recently, and partly because it can never be numerically strong.

Street Lighting From The Motorists' Point Of View

Mr. Edward Fryer
Secretary of the Automobile Association

Keywords: Lighting: Authority Organisation, Lighting: Colour, Lighting: Safety, Lighting: Specifications, Lighting: Theory, Lighting: Users

Wednesday, September 11th, 1946

A reproduction of the paper was published in: Public Lighting, Vol. 11, No. 43. October-December 1946. This includes the discussion.

Abstract: A system of street lighting which appeals to road users may not necessarily be the most efficient or the most safe. At the same time there can be no doubt that an efficient and safe lighting system is attractive to the motorist.

Dealing with complaints and comments from A.A. users, this paper analyizes types of street lighting systems and details their pros and cons. From "The Open Road" (Rural) to "Built Up Areas" (Urban Traffic Routes), the paper discusses the merits and disadvantages of these systems from the motorist's point of view. As a means of improving street lighting, a call for uniformity and some form of centralised administration is proposed.

22 years ago, Fryer presented Illumination Of Highways From The Motorist's Points Of View at the Conference On Illuminating Engineering held at Wembley in 1924. There have been developments of great moment over the last 20 years in the science of street lighting. It is doubtful whether the motorist of 1924 had seen a general standard of street lighting such as even then he was entitled to expect. Since that time the A.A. has put forward the motorist's case for better street lighting to the various official bodies studying the subject. In 1928, there was the Royal Commission On Transport; in 1935, there was the Departmental Committee on Street Lighting; in 1938 the Select Committee of the House Of Lords on the Prevention of Road Accidents. The representations made on behalf of the motorist were markedly similar and embodied what is put forward today.

The Open Road
The illumination of the open road has a very low priority. Steady advances are being made in the art of light projection from moving vehicles, with the avoidance of mutual dazzle, make it a matter of doubt whether it will ever be found necessary of expedient ot undertake road lighting on a large scale outside built up areas. There are certain aspects on the open road which do cause concern. There is a tendency for local authorities to attempt to overcome the potential danger of road junctions by installing strong lighting in an otherwise unlighted area. This can be most disconcerning and it is suggested that the intensity of this form of "isolated" lighting should be carefully controlled. The equally sudden transition into unlighted darkness again creates a potential danger - probably as great as that which the isolated lighting has been installed to overcome.

"Isolated" lighting, such as Parish lighting of a short stretch of main road, also has disadvantages. The sudden transition from darkness to light and back again to darkness may be a source of danger and confusion. There is also the problem of distracting lights adjoining the highway for some local or domestic purpose, which are mistaken for vehicle lights or even a form of street lighting. There is also the problem of lighting the approaches to towns - the edges of a built up area should be blurred for the purpose of street lighting and the transition from darkness to full intensity should be gradual, achieved within a quarter of a mile of road.

Built-up Areas
The MOT Report recommended Group A (for "Traffic Routes") and Group B ("Everything Else") for lighting. What is a Traffic Route? This position has been clarified by the provisions of the Trunk Roads Act 1946. This Act remedied what may considered to be a defect in the Trunk Roads Act of 1936 by bringing under control of the Minister Of Transport - as the Highway Authority for Trunk Roads - the parts of Trunk Roads which traverse County Boroughs and Cities. That brought the Minister of Transport into the built-up areas; and so the term "Traffic Route" is applicable to all scheduled trunk roads.

What are the main requirements of the motorist from street lighting: (1) "Continuity" - there is a lack of uniformity - leading to confusion by the lack of confidence which is created by constant changes in types, colours, heights and spacing; (2) The ability to drive at normal road speeds at night time without the use of headlamps; (3) Illumination of background - some forms of street lighting illuminate the surface of the carriageway to the exclusion of footpaths, flanking buildings, road junctions and so on; (4) - Elimination of distracting lights. Any source of light which is visible to the driver, cyclist or pedestrian, on a public highway should be subject to control of the most careful kind; (5) All kinds of traffic signs, in particular direction signs, should be illuminated; (6) The lighting of road obstructions. (Central permanent obstructions on the highway are marked with a white light and permanent obstructions on the nearside are marked with a red light).

The Departmental Committee on Street Lighting recommended the creation of an overhead authority to co-ordinate and control street lighting. The Select committee of the House of Lords on the Prevention of Road Accidents in their report (1939) endorsed the recommendations of the Lighting Committee and recommended that they should be acted upon as soon as possible. In the Interim Report of the Committee on Road Safety dated December 1944 there is the following recommendation: "We recommend that the Departments concerned should give further consideration to the Report on the Departmental Committe on Street Lighting, with a view to the early introduction of measures which will secure improved and uniform street lighting. It seems clear that this can only be achieved by the introduction of new legislation and by making the control of street lighting the responsibility of one central Department".

The Quality of Public Lighting Installations and the Modern use of the Gas Source

Mr. Crawford Sugg, B.Sc.(Eng.), A.C.G.I.
Sugg Limited

Keywords: Lighting: Colour, Lighting: Comparisons, Lighting: Control, Lighting: Distribution, Lighting: Levels, Lighting: Luminaires, Lighting: Materials, Lighting: Specifications, Lighting: Theory

Thursday, September 12th, 1946

A reproduction of the paper was published in: Public Lighting, Vol. 11, No. 43. October-December 1946. This includes the discussion.

Abstract: Stresses the principal factors which provide good lighting. There are other factors which many lighting engineers may consider as important. The total lumen light output metric of a lantern is questioned, and the advantages of gas lanterns in this area are outlined. The design and construction of post-war gas lanterns are discussed.

From the new Draft Specification: "Light Output of Lantern. It is particularly emphasised that the light output of the lantern is no guide to its effectiveness, and the luminous flux for a 100 ft. length of road is not necessarily an indication of the quality of the lighting installation; it is used only as a general index of the amount of the light to be provided."

It has become the practice to attempt to assess the quality of street lighting in terms of light output alone.

The clause quoted may be contradictory because the lumen output of a modern directive lantern would logically appear to be a guide to the amount of light provided on the road, and one would further expect a relation between this amount and the practical value of the installation. This is not necessarily the case.

It is hoped to bring out those features of an installation which will serve as a trude guide to its effectiveness but do not lend themselves to easy measurement. When grouped together contribute to "revealing power". Despite the most patient analysis, it has so far proved impracticable to evolve a simple yard stick in terms of revealing power which takes account all the conditions met with in practice.

The Contribution of the Street Lighting Engineer to Safety:
The problem to be solved is to so plan street lighting equipment and installations that there is produced a degree of visibility wheich enables all road users to see clearly, distinctly and with comfort as far ahead as is necessary for safety.

The Eyes of Road Users:
One prerequisite for a good street lighting installation, one having good revealing power, is that not only all avoidable glare be limited but the sources of light shuold distract as little as possible, so that the eyes of road users will be working in the best conditions for good visibility at night. A few really bright spots in the field of vision directing intense beams into the observer's eyes will cause the eyes to close down perceptibly and the detail of the darker parts of the scene will become invisible (disability glare). To reduce the loss of vision a nice balance is necessary between the intensity and direction of the beam of light falling on the observer and the general brightness of the whole scene.

The evolution of street lighting practice has led to two distinct methods of achieving this balance: (1) "High brightness system": High brightness of the scene and in particular the road surface is counted upon to reduce the disabling and distracting effect of lanterns which to produce the maximum brightness on the road are projecting powerful beams of light almost horizontally. Normally used in towns to avoid the "tunnel effect". It also makes a little light go a long way with the minimum number of fittings. (2) "Cut-off lighting": Screens the source at angles near the horizontal and, although this may cause of reduction in the brightness of the scene, the same, or perhaps balance, is achieved becauses the eyes of the road users are not subject to as much glare. Lanterns have to be closer together so there's a higher capital [and running] costs.

Increased mounting height is probably the most effective means for combating glare from very high brightness sources.

Source Brightness And Glare
The problem is much more readily solved when the source of light is itself of low brightness. One of the most valuable features of a street lighting lamp is that it should emit its light over a considerable area ata low order of brightness and not present an appearance of a small area of very intense light.

One characteristic which controls this brightness more than any other is the nature of the source. Most sources possess such a high brightness that it is not permissable to use them for street lighting without means of diffusing their light over an area much larger than the source, before emission from the lantern. This diffusion is combined with reflectors or refractors so that the lantern appears to be emitting light over a reasonable large area. Low brightness sources start right away by producing the required intensity of light over a considerable area.

There are various monochromatic sources distorting the preconceived ideas of colour. Silhouette vision, which comes into play at night when objects are seen against a brighter background, does not greatly depend on the colour of the background, but does depend on the background being brighter than the object. The requisite brightness of the backgroudn is dependend on factors outside the control of the lighting engineer: rain on the road surface, mist, the nature of the road surface (modern matt-surfaced non-skid roads are less polished), other moving vehicles, etc. In these cases the road user may change his mode of vision to "direct vision" and, the contrast having failed, the glare of the lantern may come into full play and further increase their difficulties.

It is inevitable that road users in busy thoroughfares will be forced to use "direct vision" to avoid danger. "Direct vision" is the natural way of seeing in daylight and colour plays a prominent part in recognition. A driver or pedestrian proceeding along a road at night in white light can distinguish the red of buses and the green of trees, etc. In the case of monochromatic high brightness lightign we are asking our eyes not only to overcome colour distortion but also at irregular movements and at short notice to change their mode of vision from silhouette to direct and vice versa, with the added distraction of visual disturbances by glare.

"Pulsating" Light
Discharge lamps emit light which is pulsating in step with the alternating electric current. The duty of smoothing these pulses into a steady light is known as "persistence of vision." It is supposed that a pulsating excitation of the optical nerves must tire them more than a steady excitation. More physiological research would appear desirable in these respects.

Steps In The Right Direction
The gas light source produces a natural continious light which is akin to sunlight and gives reasonably normal colour discrimination. This ligth is radiated from a considerable area of fabric so that the brightness is reasonably low, with the advantages of glare already shown. Why does fashion today sometimes turn from this source of light which is apparently so ideal and which is already so widely in use? The answers are: (1) The comparative novelty of the "coloured" electric sources combined with their attractive high brilliance; (2) The growing popularity of domestic electric lighting; (3) The lull with occurred in the development of gas lighting fittings, both from the point of view of performance and of appearance, between the First World War and the Second. (It was the welcome stimulus of competition with the electric discharge lamps which has since vastly altered the whole conception of how a gas lighting fitting should be constructed and used; (4) The continued existence of a very large number of "old vintage" gas installations which give the public a totally incorrect idea of what gas lighting can do; (5) General dependence on the use of lumen figures - there has been a lack of appreciation of the importance to the quality of an installation and the high light utilisation of gas street lighting equipment which is penalised on the total luminous output basis by its own high efficiency of light distriubtion. This will be corrected by the Clause in the Draft Specification and other changes assessing installations. The traditional competition between gas and electricity will then be placed on a sounder footing, even for Group A lighting, where on the present basis of total lantern lumens, the Gas Industry is faced in quoting with inconveniently high capital costs.

This leeway in development and performance has more than been made up in the space of a few years and to describe modern gas street lighting equipment which not only fulfils all the requirements of the latest draft specification, but possesses all the inherent advantages I have described which, although difficult to measure, greatly assist in producing installations of high revealing power and thus form a real contribution in the present drive towards safer roads.

The Trend Of Design In Modern Gas Lighting Units
Recent improvements in the design of gas lightign units: (1) Have yielded high and more consistent performance; (2) By radical departures in construction have provided fittings of completely modern and attractive appearance; (3) Robust construction has been adopted influencing maintenance costs; (4) Standardisation of parts have facilitated manufacturer and contributed to consistency of light output and control.

A useful improvement has been effected in the mantles, which was tried out before the war. This amounts to an increase of 5%-10% with little or no reduction in the life of 2000 hours. Standardised adjustment in daylight, by the use of a simple photometer, has been found practical and is another aid to good lighting. This follows on earlier work which standardised the gas consumption rating of lamps by the use of pressure governors and carefully calibrated gas nipples.

Relative Performance
Gas lighting is penalised on the present total lumen basis by its own efficiency of distribution. There is a balance sheet: on the Credit side is the initial light output; on the Debit side is the depreciation of the light source with age, the loss of light within the lantern itself, the loss of light by the accumulution of dirt on the lantern and the loss of light in an upward direction.

The Draft B.S. Specification permits the use of lanterns that have a maximum loss of 30% of the light in an upward direction and a maximum depreciation in illumination of 50%. This wide tolerance is necessary to premit the use of lanterns with a discharge tube source which depreciates about one-third over its life and whose light flux is not simple to control. The gas source naturally directs the greater part of its light into the lower hemisphere and usually only 5% to 15% of the light is lost upwards. The maximum depreciation from all causes, including dirt, is about 20%-25%. The balance sheets for gas and electric street lighting equipment may differ very widely because of the inherent physical characteristics of the sources: it is common for a modern low-pressure main road gas lamp to have a useful (lower hemisphere) light output throughout life which is equivalent to that from a discharge lantern having a source of double the initial lumen rating of the gas source.

The modern gas lantern may be giving 40%-50% more useful light under operating conditions than an electric discharge fitting of the same rating. Decisions on the selection of street lighting equipment should not be made until information on the efficiency of each type of lantern in terms of light radiated in useful directions has been obtained and it is important to determine whether such figures are for initial or average conditions of operation.

New Construction Methods Leading To New Appearance
Gas street lighting equipment in the past was not noted for its artistic design. The fault usually lay in the presence of a number of essential accessories attached to the lamp; these had to be kept fairly cool and could not be hidden away. Improvements are not solely for the sake of apperance; several of the designs are functional and advantages in appearance, ease of maintenance and durability have been secured simultaneously.

The Sugg 9000 lantern is built up on a one-piece light alloy casting approximately 1/8" thick. The burner can be entirely cleaned internally without major dismantling and can be put back into lighting without even a fractional change in its adjustment. The 5½ square feet of glass of the traditional lantern is replaced by a small heat-resisting globe completely detachable for cleaning. The reflectors, of a well-known type, do not tend to collect dirt and are readily restored to their new condition by wiping, having a smooth-glass-surface and being very rigidly mounted.

The Wiley Cranford is a compact lantern with a special arrangement of the control equipment which is housed in the cast box forming the socket which fits on to the top of the column.

In the Parkinson Maxilla, the whole reflector unit is an accurate stamping in anodised light alloy sheet. By ingenious design, each pane of glass is the same size to facilitate replacement and reduce glass stocks.

The prototype Sugg Panel Refractor Lantern (Southport) is constructed entirely in light alloy castings. The lantern is design to accommodate a range of light sources and control of the light is effected by specially developed Holophane refractor plates on the doors. Maintenance is facilitated by the use of cover glasses over the prisms of the refractors so that only smooth surfaces of glass have to be cleaned. The control equipment for this lantern is housed in a small box on the side which, for many purposes, is conveniently clamped direct to the column.

The Sugg London Type B/3 has recently had recently improved the ventilation system and the consistency of performance. A test of 12 lanterns showed that, on a rated peak candle power of 3000, the variation due to manufacture was only 5%. The construction is mostly of sheet copper and the reflectors are glass-surfaced.

Such consistency of performance is only attained by systematic inspection during manufcture.

Constructional Materials And Design Methods
The use of light alloys for street gas lamp construction has only been introduced after long practical experience under all conditions of service. The same severe duration tests have been applied to such subjects as reflectors surfaces, mirror backings, mastics for mounting mirrors, burner materials, glassware etc., and it is on this fund of experience that the latest methods of construction are based, together with the principles of standardisation and interchangability of parts. It is only because the Gas Industry possesses several complete lighting research laboratories that full advantage can be taken of this experience.

Centralised Control
Normal practice is to provide a clock operated controller for each lamp which required regular winding and probably also resetting. Equipment is now available which will control any number of Gas street lamps from one central point either by hand or automatically from the master clock controller. This equipment is very simple in construction and involves the use of a small diaphragm-operated valve on each fitting and a pilot pressure pipe between the fittings. Local control of each lamp is also retained and, as a safety precaution, any damage to the system as a result of an accident, leaves all the lights alight. Another system, tried out successfully before the war, made use of pilot wires and electrically-controlled clockwork operated gas cocks.

Experimental Applications of Tubular Fluorescent Lamps to Street Lighting

Mr. L. J. Davies, M.A., B.Sc. and W. D. Sinclair, A.M.I.E.E
B.T.H. Limited

Keywords: Lighting: Distribution, Lighting: Installations, Lighting: Lamps, Lighting: Levels, Lighting: Luminaires, Lighting: Specifications, Lighting: Theory

Thursday, September 12th, 1946

A reproduction of the paper was published in: Public Lighting, Vol. 11, No. 43. October-December 1946. This includes the discussion.

Abstract: Outlines the properties of the fluorescent tube, explains the pros and cons of the lamp and describes various outdoor experiments to test its durability. Then builds a theoretical lantern that meets the requirements of the B.S. Specification, which turns out to be too big and cumbersome. The lantern's requirements and scope is then more precisely defined, leading to the development of the 3-80 Lantern prototype which is then installed in Rugby and London.

1. Introduction
Deals with the feasibility of street lighting with tubular fluorescent lamps and includes as a main part descriptions of two experimental road installations.

During the war years, the lamp engineer, by the very needs of the times, have been urged to develop several new varieties of lamps. In addition, the special requirements for maximum production have resulted in a considerable raising of our standards of interior lighting. A great deal of both lamp and lighting progress centres around the extensive use of the tubular fluorescent lamp. It should not be confined to indoor installations or decorative outddor use but research has been undertaken into its use in coal mining and street lighting. The results of experiments indicate that tubular fluorescent lamps play an interesting part, and may be a very important part, in street lighting.

2. The Relation Of The Light Source To Other Street Lighting Factors
Consider three main factors:

  • (1) The reflection characteristics of the road surface
  • (2) The permissible number of lighting points per unit length of road
  • (3) The lantern performance
Note that the light source is not mentioned. This implies that no variation of very great signigicance is found in the main characteristics of the various light sources, or that light sources are selected for street lighting to have certain characteristics, enabling the lamp to be taken as a constant. However, significant variation, from the point of the lantern designer, is the size or brightness and shape of the lamp for a given wattage.

Consider a point source: lanterns can be small and light, precision built to give a close and accurate optical control, give very good brightness patterns (if sited correctly) but inherently have glaring qualities (ideal siting and absolute angular accuracy are not easily obtainable and patchy distribution and increased glare may result). Consider a large-size lamp: optical control difficult without impracticably large reflectors and large lanterns, much more tolerance is allowable in siting and mounting, and the discomfort glare is less because of the use of the low intrinsic brightness lamp.

The nature and condition of the road surface introduces a variable over which there's little control. On wet surfaces, the point source type of lantern gives thin lines of light which can become almost blinding. But with elongated lamps placed across the direction of the road, the surface reflection effect is considerably broadened and the streak width will never become dangerously narrow or its brightness excessive.

Therefore the case for a low-brightness elongated lamp can be made with respect to street lighting.

3. The Problem Of Lantern Design For Tubular Fluorescent Lamps

(a) The Lamp
The fluorescent lamp consists of a tubular glass envelope into each end is sealed a filamentary electrode with connect caps. The electrodes are coated with a thermionic emissive preparation and have small uncoated collector plates. The electric discharge passes between these electrodes through a low pressure of mercury vapour - this radiates a maximum amount of ultra violet light, which excites a coating of fluorescent powder on the inner surface of the lamp. 90% of the light comes from this powder so the colour quality of the light can be controlled at will. To enable the discharge to be started a separate circuit component known as a starter is commonly used (although switchless or self-starting circuits are possible). The starter serves to preheat the lamp electrodes and after a controlled time interval of about one second, opens to cut off the preheating current and cause a voltage surge which starts the lamp. The discharge is stabilised with a choke and power factor controlled by a capacitor.

(b) Cold Weather Behaviour
There may be some fears regarding cold weather starting. As the temperature of the lamp envelope falls, the vapour pressure of the mercury also diminishes. Tests have been carried out on this point: (1) Lamps have been operated in the open under street lighting conditions for months, at 250V AC and no difficulties have been experienced; (2) 80W fluorescent lamps were studied at low temperatures in a cold store: a 16 point installation was installed on a 240V 50 cycle AC supply with lamps in open lanterns in an ambient temperature of -10C to -5C. The light output was found to be 80% of the normal 20C free air operation. With a continuous run for a period of 4500 hours, it was found that lumen maintenance and survival characteristics of the lamps were similar to normal operating. (3) In a further 3000 hours, the lamps were used for periods of 1 to 8 hours and satisfactory starting and run-up conditions were reported. (There was a slight difference in the starting behaviour of the lamps where 75% started immediately whilst the remainder required a longer time - up to one minute). No troubles should be experienced unless voltages and temperatures are abnormally low.

(c) Colour And Efficiency
For the two "white" colours on the market the efficiencies are 35-40 lumens per watt.

(d) Variation Of Light Output With Mains Voltage
A variation of 1% in the supply voltge gives a light output change of approximately 1%.

Lantern Design

(1) Arterial Road Lighting
Research and experience over many years has culminated in compromise balances of the factors of cost, road brightness and limitation of glare, which offer the best visibility for the money. The aim of the lighting engineer is to produce on the road surface and other backgrounds, uniform levels of brightness against which objects can be discerned as dark shapes against the bright background. The inherent low brightness of the fluorescent lamp is a most helpful feature in discomfort glare, as variation of source brightness influences this considerably. If many lamps of low brightness have to be used in order to get a great flux from a single lantern, the flashed area of the lantern increases, and the advantages gained by the use of the low brightness sources may be largely offset.

A typical polar diagram of light distribution to produce the desired road surface and background brightness at wide spacing is one with peak intensitites of 5000 candles. The highest intensity than can be obtained with anodised aluminium reflectors of practicable dimensions and using 80W lamps is 1500-1800 candles. Therefore three fluorescent lamps in such individual reflectors would be required. This means for a complete fitting, a minimum of seven 80W fluorescent lamps, three in each direction to produce the main beams and one situated beneath to fill in the distribution smoothly. Such a unit would consume 700W and with an efficiency of approximately 60% would have a light output of about 12,000 lumens. A 5-lamp, 400-watts lantern is considered more practicable.

(2) Civic Centres And Shopping Areas
While it would be possible to install lanterns having flux outputs on to the road as great as with normal street lighting lamps, the size and weight of the lanterns would cause the effort to be considered an interesting experiment and no more. On the other hand, if an application could be found in which the good colour and absence of glare could be specially adventageous, a smaller lantern, at closer spacing, would be not only interesting but practicable i.e. the lighting of civic centres and shopping areas. Where heavy traffic flows the principles of silhouette vision cannot be fully used, as the background is partially or wholly obscured by the traffic. Also the capital value of a busy town centre permits a deluxe system, and this and the many traffic intersections allow a closer spacing than 120/150 ft. The lantern distribution required is therefore different, and experiment shows that it can be obtained by the use of three 80W lamps. Prototype lanterns have been installed in trial installations.

(3) The "3x80" Lantern
Takes three 80W tubular lamps. Designed to give good distribution with lantern spacings of 80 to 100 ft. at a mounting height of 25 ft. "Anti Glare" shields were modified the normal parabolic distribution, so light striking the underside of the glare shield is redirected to the roadway at a useful point, giving a controlled cut-off distribution. The wide beam spread is not an undesirable effect as kerbs, pathways, and the faces of buildings are well illuminated and enable a good visibility at the roadside. The lantern is self-contained: chokes, starters and power factor capacitors being built in. Access to one end only is required for relamping and starter replacement. The fitting is weatherproof witha plastic enclosure easily removed for cleaning purposes by the operation of a toggle catch. All the anodised aluminium reflectors are located in cast frames with both internal and external profile supports. The alloy supports, with the main tubular spar, form the framework of the whole structure. The roof structure and plastic enclosure are carried by this chassis and a light, strong fitting results. Gaskets together with a very substantial deep beading ensure the fitting is watertight. The weight is about 65 lb. The fitting is arranged for top-entry.

In the Old Bond Street and Rugby test installations, lanterns are mounted on a double wire span system with the fittings mounted between the cables on pulleys. A very simple tractive wire device is provided to enable the lanterns to be pulled in to the kerbside for servicing.

(4) Side Street Lanterns
These can make use of smaller wattage lamps. A number of experimental lanterns have been studied optically.

4. Some Practical Results
Visually the lighting is extremely good, even making allowances for the favourable spacing used. The high background brightness of a pleasant colour maintained on pavements and buildings with low glare, provides for pedestrians and motorists a useful attractive lighting of a very high order under both dry and wet conditions.

5. Conclusions
The results indicate that for town centres, traffic areas, deliberately selected for the first installation tests, a new type of street lighting is created by the fluorescent lamp. It is probable that the costs of installations will be higher than alternative systems, but not necessarily prohibitive, taking into consideration the superior results obtained. Open-air tests for many months of large and small experimental lanterns indicate no undue problems of weathering or maintenance. Installations of the residential or side street type will next be tried. There is no doubt that the possible use of fluorescent lamps should be most energetically pursued.