Recent increases in the cost of electrical energy have caused lighting authorities to review their policy on the provision, operation and maintenance of street lighting. There is also an increased awareness of both light pollution and CO2 emissions, and these are often cited as additional reasons to switch off street lighting. However, such decisions need to be balanced against the major benefits that accrue from the provision and operation of appropriate and well-maintained street lighting. The benefits of lighting are lost when the lights are switched off, whereas if the lighting is reduced to a lower level it will still provide appropriate illumination, giving security and safety to all road users, particularly pedestrians and cyclists.
There are many ways in which the use and thus the cost of electrical energy for street lighting can be reduced; however, these will generally require the authority to “Invest to Save”. This project reviewed the ways in which authorities can make savings in energy use and the cost of providing street lighting, without necessarily switching off. This report makes a number of recommendations towards this objective. These include:
• that lamp type and lighting class are chosen carefully, in accordance with the British and European Standards,
• that appropriate cost-benefit analyses are used to compare the different options when setting policies and procedures, or when replacing existing street lighting,
• that traffic signs and bollards be illuminated only when required under photo electric cell control and not 24 hours per day as is common,
• that street lighting should only be switched off or removed where this can be demonstrated as safe and practical, and after community consultation,
Typical energy costs and details of the calculations of potential savings from implementing variable lighting levels are presented, for a wide range of street lighting scenarios. Several case histories are also given as further demonstrations of what can be achieved.
Other titles in this series:
SL1 ‘Review of the class and quality of street lighting’. G I Crabb, R Beaumont and D Webster. TRL Published Report PPR380. 2008
SL3 ‘Review of luminaire maintenance factors’. A Sanders. Mott MacDonald. 2008
SL4 ‘The use of passively safe signposts and lighting columns’. GL Williams, J V Kennedy, J A Carroll and R Beesley. TRL Published Project Report PPR342. 2008
SL5 ‘Review of the lighting requirements for traffic signs and bollards’. J Cooper, K Stafford, P Owlett and J Mitchell. TRL Published Project Report PPR382. 2008
SL6 Guidance on the lighting requirements for traffic signs and bollard. J Cooper and J Mitchell. TRL Published Project Report PPR383. 2008

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