Work started this week to improve street lighting on slip roads serving the M4 at junction 7, near Slough in Berkshire.
A total of 123 streetlights will be replaced, on the eastbound and westbound entry and exit slip roads, and along the Huntercombe spur road to the A4.
Signs and safety barriers along the road will also be upgraded as part of the scheme, which is expected to be completed in six weeks.
Highways Agency project manager Graeme Steward said: “The lighting along these slip roads was installed in 1972, and has reached the end of its useful life.
“Replacing it will help keep journeys on the M4 safe and reliable for the thousands of drivers who use junction 7 every day.”