Design Criteria for Adaptive Roadway Lighting

CHAPTER 5. CONCLUSIONS

The design criteria defined in this report provide the basis for development of a method for selecting lighting level in the roadway based on time and traffic as well as for the implementation of adaptive lighting. These criteria are based on the analysis of safety in the roadway based on the lighting level. General conclusions are as follows:

• This research verified a strong relationship between safety and the presence of lighting.
• The relationship of the actual lighting level to safety was not as strong as the no-lighting condition. This provides flexibility in the selection of lighting based on design criteria while maintaining the safety level.
• The current lighting levels may be higher than required for safety on the roadway. For interstates and freeways, there is a potential to reduce the lighting level by as much as 50 percent from the current recommended practices.
• A method was developed, based on previous work, to provide both lighting level selection criteria and a method for adaptive lighting selection.