A section of the Embankment will be closed for urgent repairs tonight, at the Old Laira Road junction.
A South West Water cover has collapsed on the outbound side, between the slip roads to and from Old Laira Road.
One lane is already closed but the repair cannot be carried out safely without a full road closure, which will be in place from 9pm.
Drivers will be able to turn off at the junction and take a small diversion via the mini roundabout back onto the Embankment.
HGVs will not be able to make this manoeuvre and will be diverted via Old Laira Road, Lipson Vale, Alexandra Road, Mutley Plain and Mannamead Road onto the A38.
All the works will be completed and the road reopened overnight.