Reduced Energy Lighting - White Light Sources

Publication type:Report
Published date: 05 March 2012 08:13
Authors: Capita Symonds
Document Reference: 514324
Publication Date: 05 March 2012 08:13
Assessment Level: Addition to the evidence pool
Peer Review Information: N/A
Topics: No related topics

Executive Summary

A 2km section of the M4 between J5 & J6 has had its 250W high pressure sodium (SON) lamps replaced with 140W Cosmo white lights. These white lights use less energy, and emit half the light output compared to the SON lamps and this represents a deviation from prevailing British and European standards. However there is reason to believe the human eye is more responsive to the white light and therefore needs less of it to function effectively compared to under SON lighting. This site has been monitored since it was introduced at the beginning of April 2011. Both quantitative and qualitative evidence has been compiled in order to determine what impacts on road users and road workers might have resulted from these white lights. The evidence (to date) suggests that the white lights have not reduced safety for road users and may have improved safety for road workers.

The evidence suggests this work could be safely extended to include further example sites in order to suitably inform the development of policy for the wider use of reduced energy white lighting on the motorway network.