Abstract
For many years road lighting has seen little change compared with interior lighting. It has certainly had to adapt to the use of different light sources but otherwise it has been divorced from architectural fashion and the enthusiasms of lighting designers. The underlying technical approach and the relevant design criteria have not changed for many years despite the increasing effectiveness of vehicle headlights. This stability will not last much longer because road lighting will soon be hit by two disruptive technologies.
The first to arrive will be the increasingly sophisticated capabilities of sensors and communication systems. When these are combined with LED installations, the potential for constructing road lighting that is responsive to environmental conditions and user demand is great. There are already road lighting installations that can adjust their light output according to traffic density and weather conditions and that provide feedback to managers about the system’s status and the need for maintenance, but this is only the beginning. Vehicle-to-infrastructure communication systems that will warn drivers of hazards ahead and of city lighting that follows the movements of pedestrians are being actively discussed.
No doubt road lighting could evolve to cooperate with such developments without a fundamental rethink but this will not be possible with the arrival of the second technology. This also involves sensors and communications technology but now focused on the vehicle. It is the autonomous vehicle, a.k.a. the driverless car. It is predicted that by 2040 most vehicles sold with be autonomous. This raises an interesting question. If there is no driver who needs to see the way ahead, is the rationale for providing much road lighting gone?
The potential represented by these impending technologies suggests to me that now would be a good time for all those involved in road lighting to ask themselves some fundamental questions. What is the purpose of road lighting? If it is no longer necessary to allow drivers to see where they are going, what is it for? One answer is that streets and roads are used by people other than those in vehicles. Pedestrians and cyclists also want to move around at night and they want to do so in safety. Further, is it true that people occupying autonomous vehicles would accept travelling without any lighting of their surroundings or should all people and vehicles outside at night carry lighting which identifies them? Once the purposes of road lighting have been established it will be necessary to consider how to fulfill those requirements. This will call for careful consideration of what are the necessary amounts, spectra and distributions of light and where and when they should be delivered. So far, so functional, but it should always be remembered that lighting at night can also make a location attractive and even beautiful. Road lighting does not often achieve this. Perhaps, in the future, freeing much outdoor lighting from the shackles of road safety might enable it to make a more positive contribution to life’s pleasures.