The Highways Agency has announced that motorway lighting will be switched off at two sites in the south west to help reduce CO2 emissions and light pollution.
Carriageway lighting on the M4 between junctions 21 and 22 near Bristol will be turned off from March 26, while the switch will be flicked off on the M5 between junctions 29 and 30 near Exeter from April 16.
The lighting will be turned off between midnight and 5am.
The Highways Agency says that both stretches 'have an excellent safety record and very low traffic flows' between the selected hours.
Ginny Clarke, chief highway engineer at the Highways Agency said: 'We are looking for ways to reduce the carbon footprint of operating the motorway network and this is one step in that direction.
'We expect savings of up to 40% in both carbon emissions and energy use for each section of motorway and local communities will benefit from reduced light pollution of the night sky.'
Timing devices will control when the lights operate, but the Highway Agency's regional control centre can override the system if necessary.