Safety improvements are being made on the A66 between Braithwaite and Portinscale, says Highways England.
They include improvements to footpaths, cycleways, markings and traffic signs.
The work will start today and is scheduled to last for up to four weeks.
Temporary traffic lights will be in place but not usually between 9am and 4pm. They will be outside peak travel times to help reduce the inconvenience to road users.
Work is also being carried out on the A66 at Embleton.
This is designed to reduce flood risk on a one-mile stretch of the road. It is expected to be completed by the end of this month.
Temporary traffic lights will operate 24 hours a day and full road closures in both directions will also be required on some nights between 8pm and 6am and at some weekends.
A lane of the westbound carriageway on the A66 at Bassenthwaite Lake, which was closed because of storm damage in December has reopened.
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