Electric Lighting for Marshalling Yards PDF

8. MARSHALLING YARD LIGHTING 8.0 INTRODUCTION Marshalling yard covers a huge area in thousands of square metres and comprises hundreds of metres length of rail tracks and innumerable junction points. During the hours of darkness, the men who keep things going in this extensive area are...

8. MARSHALLING YARD LIGHTING 8.0 INTRODUCTION Marshalling yard covers a huge area in thousands of square metres and comprises hundreds of metres length of rail tracks and innumerable junction points. During the hours of darkness, the men who keep things going in this extensive area are busy at various tasks. They can only work efficiently and safely if adequate lighting for visual tasks are available even after sunset, 8.1 MECHANISM OF MARSHALLING YARD To gain an insight into the lighting problem involved in shunting of railway wagons, one must have some idea of how this is done and how a marshalling yard is equipped. A marshalling yard acts as clearing house for the wagons which have to be distributed over different tracks. In this way, trains are made up of wagons having the same destination. Thus, in principle, every marshalling yard consists of a main feed line which spreads out fan-wise in a number of tracks on which the various trains are made up for number of destinations. There are two types of marshalling yards - one with flat switching and the other with hump switching. On a flat marshalling yard the wagons for a certain track are pushed off by the shunting engine accelerating for a moment and then suddenly braking. For pushing off of each wagon or cut off wagon, the engine has to make a short run again and again. On a yard with a high shoulder of grounds, also called the hump, the cut off wagon is pushed with constant speed against the crest of the hump. Just before reaching the crest the wagons are uncoupled by a shunter with the aid of the hook. The wagon thus released, drops down by their own weight on to the track, being switched on the correct line for which the wagons are destined. In smaller shunting yards the switches are mostly operated on the spot by the shunter; while the modern marshalling yards with hump are equipped with marshalling cabins having operation panels representing the entire grid of tracks, on which every wagon in motion is indicated. The switching operation is done from the cabin for directing the wagons as per the desired destination track. On being pushed away and also being released from the hump the wagons often gather too much speed. Marshalling yard with a shunting hump is usually equipped with a braking bridge for the braking of the wagons, which is operated from the marshalling cabin. 8.2 VISUAL TASKS & ILLUMINANCE REQUIREMENT More and more work in marshalling yard is concentrated in a few key-points like top of the shunting hump, around the braking bridge and around the area where the switches are located. However, to facilitate the intensive scale shunting and assembling of trains, to improve productivity by speedy movement, to reduce accidents, to allow safe movement of wagons and railway personnel and to have better security and reduction in personnel and reduction in theft, it is essential to light up the entire marshalling yard having glare free general lighting. The recommended average illuminance in a marshalling yard varies from 10 to 20 lux. Of much more importance than the illuminance in marshalling yards, is the creation of bright images by reflection of the light sources in the surface of the railway tracks. These gleaming tracks afford a clear contrast between the rails and the surroundings; 44 an interruption in gleaming tracks indicate the presence of the wagons and other obstacles and movement of wagons is also much more easily observed in this way. The obstacles are observed as silhouette without details. 8.3 HUMP AREA Special attention should be given to the lighting of the hump area. Operation must have a clear view in both directions without glare so that the chalk numbers on approaching wagons, the setting of the points and the amount of clear track left in each of the train sidings etc. can be seen easily. Viewing from the hump area, vertical plane illuminance also becomes important in assisting the identification of wagon markings or judging the speed of approaching or receding wagons. The recommended value of illuminance in the vertical plane is 30 to 50 lux. This can be achieved by low or medium height installations", where broad beam asymmetric floodlights are most appropriate. 8.4 DESIGN CRITERIA The performance of all above activities and achievements of quantitative and qualitative requirements of lighting call for various illumination engineering techniques like choice of type of installations, luminaires and light sources, aiming of luminaires, maintenance, etc. 8.5 SYSTEM OF MARSHALLING YARD LIGHTING Different railways have adopted lighting system depending upon the size and complexity of yard, which can be divided broadly into the following types. High Tower lighting system - Distributed lighting system Gantry lighting in main areas Combination of the three to cover different areas. There are no simple thumb rules for deciding the use of a particular type of installation. A careful analysis of many factors is necessary' in the context of the specific requirements and the particular local conditions. However, the major requirements of high tower installation is the high efficacy light source and narrow beam floodlight luminaire. 8.5.1 High Tower Lighting System The recent experiments have indicated that there are many advantages in extra height of tower. Some of the advantages of high tower installations may be listed as follows: Large areas can be illuminated from relatively few positions, thus minimising the amount of obstruction in the working area. Cabling costs are lower as supply is required at only a few points. The glare is reduced. The whole of the light appears to come from the sky, or the uniformity at ground level is very good and the lighting is shadow free. Maintenance is facilitated as the floodlights are concentrated in batteries on tower platforms and in turn it results into reliability. Since there is a considerable overlapping of beams on a large installation, failure of one lamp does not result in an area of darkness. 45 Disadvantages In the proximity of air ports, the permissible height is restricted. Access to flood light projectors is hazardous, particularly in bad weather. More space is required between the railway tracks. Shadows become inevitable and lighting between lines cannot be fully arranged. Light sources and lurninaires This higher mounting height and their advantages now can be utilised in our country mainly due to the availability of indigenous high efficacy, high pressure mercury vapour (HPMV) and high pressure metal halide light sources and HPSV lamps of 250 & 400W. These light sources can be used in better optically designed floodlight luminaires. The optical characteristics of the luminaires are such that it gives comparatively narrow beam light distribution, This is achieved by the scientific design of the reflectors and the highly specific mirror like finish of the reflectors For marshalling yard lighting the floodlight luminaires should be heavy duty type and weather proof. The housing should be of cast aluminium alloy so that the same can withstand the normal seasonal weather conditions at that height. The reflector should be of anodised aluminium and mirror like finish for better optical control. The luminaires should be provided with heat resistant toughened glass cover in the front along with polychloroprene gasket to make the luminaire completely weather proof. The luminaires should have the earthing terminal for the safety requirements. The design of the luminaires should be such that replacement of the lamp and other maintenance is easy. The electrical accessories required for the operation of the light sources should be designed and manufactured for optimum efficiency and life. Aiming of floodlight luminaires Having selected the tower height, light source and luminaires, the quantity requirement of the floodlight luminaires to achieve the illuminance desired is a matter of simple mathematics. However, in practice it is important to achieve the desired illuminance in horizontal and vertical planes, the desired uniformity ratio and glare free lighting in illumination of the marshalling yard. In the absence of the guidelines from the designer with regard to the aiming, this task is difficult. Usually in such cases it is customary to employ methods of trial and error involving a number of people working late and thereby incurring wasteful expenditure. Instead of this it is possible to prepare a detailed aiming diagram which gives accurate results of illuminance., uniformity or glare free lighting. Having obtained this diagram the use of 'Night Time Visual Method' or 'Daylight Aiming Methods' can be employed. The latter method also makes use of specially designed azimuth device and elevation angle device to set the horizontal and vertical angles of each of the floodlight luminaire. Safety measures Whatever type of installation is employed, safety requirements from both operational and maintenance points of view must be fully considered. Towers or poles can be sited only where ample clearance between the lighting structures and the overhead electrical equipment is available. 46 Maintenance If the luminaires are at greater height, certain maintenance problems also come into the picture. However, upto a height of approximately 30 M. towers may be climbed by making use of structure itself. Apart from this there are some advantages of the higher mounting height. As the luminaires are located at fewer points the replacement is easier. In such cases, the group replacement scheme is the most suitable, as the replacement of individual lamp at the time of failure is a very costly affair To get maximum benefit of the high lumen pack light sources and luminaires the periodical cleaning of luminaires should be done at regular interval. For the marshalling yard located nearer to sea the hardware and movable parts should be treated with lubricant for ease of maintenance. 8.5.2 Distributed lighting system Advantages Lower mounting height. Less of directional beam. More uniform illumination and effective utilisation of lights. Reduction of shadows. Reduced loss due to atmospheric absorption and scattering. Disadvantages Large number of physical obstructions. Elaborate distribution network, Maintenance over large number of points. Failure of lamps cause dark spots. Special care is to be taken for ensuring visibility and sighting of signals. 8.5.3 Gantry lighting This consists of erection of gantries over the spread of raiway tracks across the yard and providing illumination between tracks by seperate lights. Advantages Gives excellent illumination for working. Eliminates shadows. Easy maintenance and acceptability. Disadvantages Very expensive in first cost. Can be used only in the main central portion of receipt,classification and, dispatch yards. 8.5.4 Combination Most effective planning of yard lighting can be done by combination and judicious mix of all the three systems with a view to achieving the objectives at optimum cost. Design can be best suited for particular location in each area of the yard. Different railways world over have adopted one or the other of these systems for lighting the yard. Indian Railways have a mixed practice, but in a majority of yards light fittings on high towers with HPMV lamps and recently with HPSV lamps is more common Adoption of a system depends on the availability of the space, capital costs, level of illumination and desirability of shadowless lighting. 47 8.6 SPECIFICATIONS FOR MARSHALLING YARD LIGHTING SYSTEM 8.6.1 Scope The scope of this specification covers the illumination design for marshalling yard. The specification also covers the design and supply of floodlighting towers, luminaires and light sources including total installation but excluding electrical system. 8.6.2 Operating conditions All the equipments shall be capable of continuous operations when exposed to all normal seasonal weather conditions in the country: Ambient air temperature – 45°C average Maximum relative humidity – 100% Supply voltage – 230V +/- 5% single phase 50Hz A.C. System. 8.6.3 Objectives The basic functions of marshalling yard lighting shall be to provide: 3.1 Facilities for the intensive scale shunting and assembling of trains and thereby improving the productivity. 3.2 Adequate lighting for the safe movement of wagons and railway personnel and thereby reducing accidents. 3.3 Adequate lighting conditions for security and thereby reducing theft. 8.6.4 Design criteria While designing the marshalling yard lighting system, the following factors shall be considered individually as well as together as a whole: Obstruction clearance The location of the floodlighting towers shall be such that ample clearance between the lighting structure and overhead electrical equipment is available. The location of the floodlighting towers shall not cause any obstruction of view either to the control cabin personnel or to the railway shunting staff, Illuminance levels The illumination design shall be such that an average horizontal illuminance of 10 lux is provided on the surface level of the marshalling yard and the vertical illuminance is 10 lux and 15 lux when looked along the direction of track or perpendicular to the track respectively. Illuminance Uniformity Uniformity of illuminance shall be maintained throughout the body of the marshalling yard where uniformity ratio (Emin / Eavg) shall not be less than 0.2 and in hump area the uniformity ratio (Emin / Eavg) shall not be less than 0.35. Glare control The mounting height, the light distribution and the aiming of the luminaires shall be such that minimum glare is caused to the shunting staff or to the operating staff in the control cabin. Low mounting luminaires shall be avoided to prevent glare to the shunting staff. If necessary, suitable screening louvres shall be fixed on the luminaires to prevent glare. 48 8.7 LIGTING OF AREAS OTHER THAN MARSHALLING YARDS 8.7.1 Railway stations Platforms Good platform lighting on small stations as well as large is essential for the safety and comfort of passengers as well as railway staff. Low built platform roofs offer better possibility for mounting the luminaires with proper distribution to provide optimum lighting conditions from the light incidence and distribution points of view. Modern luminaries with T5 fluorescent lamps are best suited for the purpose. The fittings may be spaced symmetrically and so located to avoid shadows. The T5 fitttings may be suitable luminaries of 2’ or 4’ feet as required. The luminaires should be arranged in such a way that the light strikes the platform edge straight down and without shadow and at the same time provides reasonably uniform lighting right across the width of the platform. Generally, the recommended value of illuminance is 150 lux in Class A Model stations in the covered portion where as it is 100 lux in class A non model stations. The railway board has published the details of illuminance level required in covered as well as non-covered areas for Class A,B &C category model stations as well as non-model stations. For the non- covered portion of the railway station, street light fittings of (4 Nos x 2’) T5 fluorescent lamps with wide angle distribution reflector are suitable. Modern LED street light fittings of 36/40 W also will be suitable for the purpose. 8.7.2 Goods depots Normally, goods depots consist of siding for loading and unloading and standing or berthing sidings. The usual attention has to be paid to lighting the switch points and capstans and should be well lit to ensure their safe operation. The luminaires using either metal halides lamps are recommended. Suitable high masts with metal halide lamps can be provided. However HPSV lamps can be provided in small goods depots particularly when colour rendering is not important The main concern is the loading and unloading area with its associated traffic space. Motor road systems within the yard should have average 30 lux for group Al road lighting as per IS:1944-1970. The illumination of the loading area has to be raised to facilitate the reading of labels, schedules, etc. The illuminance value of 100 lux should be provided in the loading area.. Low or medium height installations using broad beam asymmetric floodlight luminaires are most appropriate for these areas. The recommended light source is metal halide lamps of 250/400W. The layout of towers/masts should be such that the system must give sufficient clearance for maneouvering of vehicles and movements of cranes, and high enough for light penetration into open wagons. 8.7.3 Carriage cleaning siding Cleaning sidings are normally provided with narrow platforms between the lines of coaches to facilitate access by the cleaners while the electricity and water supply, points are installed at approximate 'coach length' intervals along the middle of the staging. The task involved requires good vertical illuminance and shadow free lighting. The general illumination on the narrow platform should be good enough for safe movement of the personnel. The luminaires should have the wide beam optical characteristics and also should be splash-proof type to have the protection against the water coming from any direction. The luminaires should be mounted on the poles closely placed along the tracks 49 8.7.4 Locomotive fuelling area These areas may be single or double, according to whether the oil and water supply points are situated along side one or between a pair of tracks. It must be possible to handle pipes easily and safely and also gauge readings should be clearly visible on the supply points and locomotives. In the open type of fuelling area an illumination of at least average10 lux should be provided. The luminaires having proper light distribution mounted on low height poles should be located between the locomotive and line of supply dials, thus illuminating both. 8.7.5 Locomotive yards Locomotive yards are the standing sidings adjacent to servicing and repair sheds and all that is needed is lighting for the general movement and safety. A value of 2 - 5 lux will meet the requirements. Light weight floodlights having wide distribution can be mounted along the face of the sheds for adequate lighting. -------------------------------------- 50