The street lights on 4,000 miles of motorway and trunk roads in England may be switched off between midnight and 5am to save energy and cut CO2 emissions.
Research is being carried out to see where this can be done safely prior to the publication of the Highways Agency's energy efficiency strategy next spring.
Lighting levels might also be reduced before midnight on major junctions and approaches to towns and cities that are at present lit, although large sections of the road network remain unlit.
The agency is also considering whether to use more energy-efficient lighting, which experts believe could cut both CO2 emissions and energy consumption by up to 40%.
Similar initiatives are also being considered, or have been introduced, by a number of local authorities - including West Sussex, Gloucestershire, Hampshire, Essex and Powys - that have either switched off some street lights or are considering doing so.
The review has been prompted by research that now estimates lighting between motorway links reduces the risk of night-time accidents by only 10%, which is a third of what was previously believed.
Copyright © PA Business 2008