ABSTRACT
All forms of lighting are subject to constraints and lighting for driving is no exception. These constraints range from the legal through the financial to the environmental, some of them being weak and some strong. Vehicle lighting meeting specific photometric conditions is a legal requirement in almost all countries. Road lighting is not a legal requirement but rather a matter of policy, the nature of which will vary from country to country and from time to time. Both vehicle lighting and road lighting imply costs. For vehicles, the first costs of lighting are included in the cost of the vehicle. Costs-in-use are borne by the driver and depend on the timing and hours of use of the vehicle. For road lighting, both first costs and life cycle costs can be involved in the decision whether or not to install road lighting and certainly influence the amount and form of road lighting provided. Recently, environmental factors have also entered into consideration, particularly for road lighting. These environmental factors can take four forms: the amount of energy consumed, the carbon dioxide emissions produced when generating the electricity used, the disposal of the materials used at the end of product life, and the problem of light pollution. This chapter is devoted to a consideration of these constraints as they apply to road lighting. The legal requirements applicable to vehicle lighting have been discussed in Sections 6.3 and 7.3. The financial and environmental aspects of vehicle lighting are not considered separately from those of the vehicle itself. Even the light pollution produced by vehicle lighting is ignored, probably because it is considered to be transient rather than permanent.
