|A typical geared MA60 column on the A12 in East London. These are now being replaced with iridium based lanterns.|
|Pictures related to Street Lighting|
View gallery (904)
Street lighting is used for a variety of reasons, the primary two that are cited are to improve road safety and reduce the fear of crime.
Historically using torches, then gas lamps, modern electric street lighting has been available since the late 19th century. Technology has made street lights automatically turn on at dusk and off at dawn, and to protect the circuit against individual failure.
There are numerous type of street light design available and these are generally chosen by a lighting engineer at the relevant highway authority. Since the late 1980s, the trend has been away from the bright-yellow low-pressure sodium (LPS) lighting and towards 'white' light, such as high-pressure sodium (HPS) and Metal Halide. Recently LEDs have become commercially viable and are being rolled out in new installations or upgrades across the UK. Various brackets have been used for mounting, originally using metal, then concrete principally throughout the 1960s and 1970s, to more flexible modern designs.
Streetlights are also what determines a speed limit on the UK road network (excluding Special Roads). A system of lighting on an all-purpose road means the default speed limit is 30mph unless signs state otherwise.
The early motorways such as the M1, M6 Preston Bypass and the M62 over Saddleworth Moor were mostly unlit, as street lighting was (and, indeed, is) not designed to replace headlamps, but to illustrate other hazards. The first main stretch of motorway to open fully lit was probably the M4 from Chiswick to Langley in West London in 1965.
By the end of the 1960s, a series of fog-based fatalities resulted in lighting being retrofitted throughout the existing motorway network. However, by 2011, a number of motorways, such as the M58, M65, and M66 were having lighting removed on environmental and cost grounds. Carriageway lighting is often being removed as part of many Smart Motorway upgrades too, save for major interchanges.
Many councils have now set their street lighting to automatically turn off from around 12 AM to around 5 AM (varies slightly by council). This is to save money on energy bills as well as reduce carbon emissions. However, there are controversies about the impact of part-night lighting on crime rates.
The following terminology can be encountered when discussing street lighting.
Catenary lighting has lanterns suspended from an overhead wire column, mounted on regular posts. It was popular in the 1960s and 1970s, and could be seen on the M1 through the home counties and the western section of the M25 around Heathrow. It fell out of favour on the main roads, due to the installations being incredibly difficult to maintain and having a poor spread of light.
Only a very small number of main road installations remain:
- The last remaining section of catenary lighting was on the M1, between junctions 6 and 6A: the installation, which used the Philips MO62 LPS lantern, has been out of use since September 2018, and was finally removed in June 2021.
- There is a short section of cross-catenary lighting on the A3200 Southwark Street, near Borough High Street. In 2015, the installation was modernised, with LPS lanterns being replaced by LED lanterns.
- There is also a short section of cross-catenary lighting on the A206 Nelson Road, from Greenwich Church Street to King William Walk. They use four Industria 2600 HPS lanterns.
New catenary lighting installations are usually part of improvements to town centres and pedestrian streets:
- In 2011, the Royal Borough of Greenwich installed catenary lighting for the regeneration of Beresford Square. The installation was developed by LAPD Lighting Design and Ronstan Tensile Architecture (source).
- In Slough, there is an installation on the High Street, running from Alpha Street North to Church Street. The style of this installation is similar to the ones formerly used on the main roads.
- In Minehead, there is a section of retro-style cross-catenary installation on The Avenue, from Blenheim/Summerland Road to The Esplanade.
Other new installations can be found at Bermondsey Square in South London. Around the Olympic Park, Arber Lane and Endeavour Square will have catenary lighting. There are also many permanent decorative installations that fall outside the scope of road lighting, such as that on the Thames Path from HMS Belfast to Tower Bridge.
Though steel was a popular choice for mounting columns, new postwar regulations in the late 1940s meant that other materials had to be used. Concrete was regularly used from the 1960s through to the 1980s for the base of a street lantern. Beyond this, it has gradually been phased out, although a few exceptions, such as West Sussex County Council, continued to install new concrete columns up to the 1990s. Concrete is starting to disappear completely now; North Yorkshire County Council went through an extensive replacement scheme in 2010.
MA lights use low pressure mercury as their principal element. They were considered problematic due to inefficiency with lighting, with very bright light that made it hard to see pedestrians, and consequently are now considered obsolete, and generally being replaced with SON lanterns instead.
These include low-pressure sodium (LPS) and high-pressure sodium (HPS).
SOX (Sodium with OXide) and SON (variant on "Sun") refer to the type of element used in the filament in a sodium based lamp. SOX is a type of low pressure sodium (LPS) light, and SON is a type of high pressure sodium (HPS) light. At a particular frequency, sodium vapour emits a very strong light, which makes it ideal for street lighting. The two can be distinguished by the colour of the emitted light - SON/HPS emits peachy orange, while SOX/LPS emits a plain yellow. One of the problems with SOX is that the sodium eventually reacts with the material of the lantern container, which ultimately results in its failure.
SOX was used for LPS lanterns and contained a mix of solid sodium with argon and neon, giving off an amber coloured light. They first appeared around 1964 and were widely used until the 1990s. SON refers to a newer type of high-pressure sodium (HPS) lantern that contains mercury. The colour spectrum of LPS (including SOX) lighting makes it ideal for road lighting as it is non-fatiguing for human eyes and penetrates fog and mist more effectively than HPS and other types. It is also considered more environmentally safe as its emissions are easy for astronomers to filter out, and are less likely to disturb other life. However, it is LPS's colour that has caused it to go out of favour by lighting professionals. Gradually, LPS lanterns are being "end of lifed" and replaced with LED or HPS.
Philips Lighting, the last manufacturer of LPS lanterns, ceased production in 2019, due to falls in demand. As a result, many LPS lanterns already in place are likely to be replaced with LED at the end of their life.
Both LPS and HPS lighting is becoming obsolete due to recent innovations in LED technology. The use in street lighting is still fairly new, but a common theme on all designs is avoiding the distinctive colour of LPS lighting for a purer white. Notable installations include the M4 through Berkshire, the M3 south of Winchester, the M6 through Birmingham and many Smart Motorway-upgraded sections of the M1.
The articles below give further technical details about street lighting.