Since C1E Publication No. 12.2, Recommendations tor tne lighting or roaas ior mwwiwu iiainc-, was issued in 1977 experience has been gained worldwide in the application of the luminance concept to the lighting of traffic routes. This has been used to update the recommendations in this revised version of the document, which also takes into account the needs of other road users, mainly pedestrians and pedal cyclists.
The recommendations are structured with the intention of making them easily adaptable to the needs of individual countries, so that they can be used as the basis for national codes of practice and standards.
In CIE Technical Reports every effort is taken to get general consensus of the Technical Committee Members. Technical Committees deal with concepts that are still in a research stage and where, by the nature of the subject, from time to time not all members of the committee can agree to every statement of the report. A description is given of two such concepts, which, because of their newness, have not been tested on a sufficiently large scale or for a long enough period of time to be recommended without reservation. Nevertheless, they potentially offer certain advantages and are included for that reason. These are visibility level and semi-cylindrical illuminance. It is hoped that users of this document will employ these on a trial basis where circumstances allow. In particular, based on their own research and experience, individual countries may adopt the visibility level concept as an alternative to the luminance concept.
Updates of the report will be published as agreement on the still controversial subjects can be reached, but the CIE felt that the present compromise solution enables all interested readers an Insight into the rapidly progressing subject of roadlighting.
In conformity with the most recent CIE practice, recommendations are based on maintained lighting levels and lighting quality. In essence this implies that performance must not fall below the prescribed limits, which are minima, for the life of the installation.
No mention is made of warrants for deciding whether a road should be lit. For each country, this decision depends on many factors including economic circumstances, density of population and traffic, and size. Since these vary greatly from country to country it has not been found possible to lay down guidelines.