The Highways Agency has said some of the lights on the M27 will be switched off in the early hours in an bid to reduce carbon emissions.
The stretch of motorway between junctions 7 and 8 near Southampton, Hampshire, will be plunged into darkness between midnight and 5am each night.
Chosen for its excellent safety record and low traffic flow during those times, the M27 will be used to trial steps to reduce carbon emissions and light pollution.
Jon Griffiths, network operations director, 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 to achieve up to a 40% saving in carbon emissions and energy use for each section of motorway where we do this, and local communities will benefit from reduced light pollution of the night sky."
Timing devices will be used to control when the lights go on and off, but the Agency's regional control centre can override the controls if necessary.
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