A 40mph speed limit will be in force on a busy stretch of the M6 as 10 weeks of roadworks get under way.
Work is now being carried out to re-waterproof Walsall canal bridge, between junction 10 for Walsall and 9 for Wednesbury.
Drivers were today warned to allow extra time for their journeys.
Work will be carried out overnight from 10pm to 6am on Mondays to Saturdays for the next 10 weeks and lane closures will be necessary.
The southbound carriageway will also be closed for 10 nights during the 10-week period, with details of dates yet to be announced.
But, while three lanes will be kept open during the day, narrow lanes and a 40 mph speed limit will be in place 24/7, highways bosses have said.
They say the current waterproofing on the bridge needs replacing.
Colin Jackson, project manager, said: “Replacing it now and carrying out any necessary concrete repairs to the bridge reduces the need for future maintenance and the associated disruption to road users.
“There may be times during construction when it will appear that no work is being carried out.
“This is because concrete needs time to cure and once poured we are unable to progress the scheme until that process is complete.
“It is also important to stress that the work is weather sensitive and, until the concrete is exposed, we do not know the exact number and size of repairs.
“If there are more than envisaged or the weather is unfavourable then the planned phases of the work and associated road closures could be affected.”
He added people should allow extra time for their journeys and be patient as they drive through the roadworks.
Road closures will be announced in advance and diversions will be in place.
Traffic will be diverted off the M6 at junction 10 and along the A454, A4148 and A34 to rejoin the motorway at junction seven.