For increased energy efficiency within the road sector, some attention has been given to road lighting. Reductions in energy use for road lighting can primarily be achieved by replacing old road lighting installations by modern ones and by reducing lighting levels by revising current road lighting recommendations. Less attention has so far been paid to current practice and standards. However, there are reasons to believe there is a realistic potential in changing recommendations for road lighting so they promote a less energy consuming lighting regime without decreasing the benefits. There is a lack of knowledge of the relationship between road users’ needs and visual condition, which gives reasons to believe road lighting may be over-dimensioned in many situations. The need for energy savings together with the fact that the current guidelines for road lighting are not well-founded from a road user perspective implies the need for a review of the current recommendations and standards. The starting point of this work has been the method for selection of lighting classes suggested in the recently published technical report CEN/TR 13201-1, which considers road lighting for drivers and for vulnerable road users. In order to investigate whether this is applicable in Sweden, a literature review on guidelines and criteria for selection of road lighting classes was carried out, with the aim of identifying criteria that are scientifically grounded. The literature review was supplemented by a workshop where road lighting criteria were discussed by invited road lighting experts from the Nordic countries. The literature review and the workshop constitute the first and the second part of a three-stage project that aims at forming a basis for further discussions and work on a possible revision of current guidelines, with the long-term goal of having more scientifically grounded and energy efficient recommendations for road lighting design in the future. The review shows that there is no strong link between the selection criteria in CEN/TR 13201-1 and the scientific literature, which is in line with previous studies on guidelines for road lighting. It is recommended that new guidelines should have a stronger base in scientific results and they should also be easy to understand and to apply. There should be limited possibilities for interpretations and their application should be equal regardless of who is using them. In developing new guidelines, the suggestion is that the factors to be considered should be road users’ needs, energy and costs. The road users’ needs must be defined in future studies, but may include for example, detectability of vulnerable road users and visual comfort. Regarding energy, guidelines for dimming and adaptation needs to be developed. Costs is a relevant factor but the traditional cost-benefit calculations should be avoided due to the weak scientific basis the estimations are based on. Also, other factors such as mobility, accessibility and light pollutions may be relevant to consider in guidelines for lighting and lighting level. Three potential ways of evaluating lighting are suggested: • Visibility and detectability of pedestrians • Glare, visual discomfort and visual experience • Subjective experience. These methods relate to the parameters in CEN/TR 13201-1 that are assumed to be relevant for the selection of lighting class, namely traffic volume, traffic composition, separation of carriageways, ambient luminosity and navigational task. (Author/publisher)
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