Highways chiefs say almost £700,000 is to be spent on safety improvements to bridges on the M6 in Cumbria.
Work is due to start on the first of three projects on 31 January - all will mean some disruption to motorists.
The Highways Agency says the work is necessary to maintain safety on the motorway, which is one of the country's most congested.
The schemes involve bridge strengthening at Shap, Thrimby, Castle Howe and Tebay.
Some £400,000 is being spent to bring a bridge over the motorway near Shap up to modern safety standards.
Drainage system
A further £200,000 scheme has been approved to strengthen piers on Greenriggs overbridge near Thrimby and protect them from crashes.
And £90,000 will go to improve the drainage system at Castle Howe and Tebay bridges.
Highways Agency project manager Bob Clark said: "These are important works to ensure the motorway is kept safe and in good condition.
"Motorists on the motorway should only experience minimal delays, but drivers on the local road network using Shap Road over the motorway should allow extra time for their journey."