Catenary lighting encompasses the suspension of luminaires from wires fixed between columns or buildings to provide illumination. There are two basic types of catenary lighting, city and motorway. In cities, luminaires can be suspended from wires fixed across the road, either between buildings or between columns positioned on either side of the road. There are two reasons for using this method of lighting. Firstly, to avoid the use of lighting columns which cause an obstruction on the pavement and can be very difficult to position in city centres due to the many services, basements and underground rail facilities etc. that may exist below ground. Secondly, wide city boulevards with trees down one or both sides cannot be lit effectively from luminaires set back amongst the trees.
In both these instances there will be one or at most two luminaires suspended and the loads on the walls or columns and support wires are not high.
On wide motorways the most even illumination and the best visual guidance is provided by a centrally suspended catenary system. The luminaires are suspended at comparatively close intervals and the light from them radiates at right angles to the road axis. This allows a very even light level to be produced over a wide 4 or 5 lane motorway from luminaires mounted at relatively low mounting heights. To produce the same illumination level with conventional systems, much higher columns would have to be used or two rows of luminaires would be required along the edge of the hard shoulder, in addition to the centrally mounted ones. The number of luminaires and their type will depend on the width of road to be lit, the lamp to be used and the lighting level required.
The levels of illumination to be achieved by catenary systems are derived from the normal road, city centre or motorway British Standards or CEN Standards. It is only the method of achieving them that is different. The luminaires, with their low profile or flat glass front, are also suitable for use on busy roads near airports or in railway marshalling yards where full cut-off lighting is important.
The planning of a new catenary system involves the design of the columns and suspension wires in addition to the luminaires. CU Phosco, with their wide experience of catenary lighting including design and manufacture of the columns, support system and luminaires, are ideally suited to provide a total package if that is required. Alternatively, CU Phosco can help with the refurbishment of older systems, whether their own or by others. In the great storm of 1987 all the catenary systems designed and manufactured by CU Phosco performed superbly and passed this severe test well beyond their specifications with flying colours.
The P400 system covers a wide range of catenary luminaires. They are all dust tight and jet proof to IP65. The body is manufactured from aluminium, which is first heavily anodised and then powder coated, with a glass front. The P400 is a front opening luminaire with either full length hinges and clamps or individual hinges and clamps as specified. Two full length internal ducts are provided to facilitate through wiring. Cable entry is either through the sides or ends of the body as required.
High pressure sodium and low pressure sodium versions are available in single or twin versions as specified. Symmetrical transverse light distribution reflectors are made for all lamps. Symmetrical longitudinal reflectors can be fitted in urban catenary systems using SON/T lamps.
Unlike almost all other exterior lighting, tunnel lighting is on generally 24 hours a day; in fact on a sunny day more light is needed in the threshold of a tunnel to give the eye time to adapt from the very high daylight illumination level down to the comparative darkness of the tunnel interior. The design of the tunnel lighting is not just a problem for lighting engineers. The design of the tunnel itself will have consequences as to the positioning of the luminaires, and the electrical supply will possibly be part of a complex system controlling ventilation fans, signalling and pumping.
For the lighting engineer the factors to be considered are:
• The position of the luminaires - fittings to the cornices will require different reflectors from those mounted centrally and generally more will be required. However they may be easier to maintain.
• The speed of the traffic entering the tunnel - on a high speed motorway the vehicle entering the tunnel will have travelled much further before the driver’s eye has adapted to the lower light level. Therefore the threshold zone and transition zone will have to continue further into the tunnel than would be the case in a city where the traffic is limited to a much lower speed limit.
• The orientation of the tunnel - a tunnel on an East West axis at sunrise and sunset will face the possibility of the driver directly facing the sun, disappearing into what will appear a black hole. It is possible to avoid this by landscaping or other mechanical means but the situation is one that must be considered.
• The length of the tunnel - tunnels less than 25m in length may not require lighting during the day as the exit is visible and daylight can provide enough light. Tunnels between 25m and 125m may require lighting depending on the speed of traffic and the road and tunnel layout. If the exit of the tunnel cannot be seen from the stopping distance in front of the tunnel, lighting will be required. Tunnels longer than 125m will require full lighting with a threshold zone, transition zone, interior zone and exit zone.
We could give lighting levels that may be required for tunnel lighting but it is a subject that should only be tackled by experienced professional engineers with a thorough knowledge of BS 5489 Part 7 or CIE 88 whichever is relevant.
The T400 system covers a wide range of tunnel luminaires. They are all dust tight and jet proof to IP65. The body is manufactured from aluminium, which is first heavily anodised and then powder coated, and has a glass front. The design pays particular attention to ease of installation and maintenance and they have been tested to withstand the adverse conditions commonly encountered in tunnels during use and cleaning.
The T400 is a front opening luminaire with either full length hinges and clamps or individual hinges and clamps as specified. Two full length internal ducts are provided to facilitate through wiring. Cable entry is either through the sides or ends of the body as required. Special clamp fittings which engage at any position on the lengthwise flanges are provided and a wide variety of bracketry to suit the tunnel designs is available.
A twin level gasket system provides a long lasting seal. Each lamp circuit, should there be more than one, is individually wired and fused. An isolator can be fitted in each luminaire, either switched manually or by micro switch on the opening of the luminaire. The control gear is fitted to easily removable gear trays which are fitted with plug and socket connections. The luminaires can be fitted with battery packs and interior units are available mounted on gear trays, in fluorescent tube versions, to provide emergency lighting in the event of mains failure. Switching can be either externally operated or the luminaire can be fitted with equipment designed to switch when a signal is received. Dimming equipment can also be fitted.
High pressure sodium, tubular fluorescent and low pressure sodium versions are available in single, twin or multiple versions as specified. Symmetrical transverse light distribution reflectors in centrally mounted or cornice versions are made for all lamps. High pressure sodium versions can be fitted with symmetrical axial reflectors
