A section of the A6 between Rothwell and Desborough will remain closed until Monday (January 23) at the earliest.
Following a routine inspection of the Desborough bypass bridge, between the A14 at Rothwell and B576 Harborough Road junction, the bridge was closed due to safety concerns late last night.
The inspection of the carriageway has confirmed there are failings under the road surface and crews are out surveying and investigating further to ascertain the extent and the actions necessary.
A signed route diverts traffic from the A6 onto the A427 junction towards Corby, where traffic will continue along the A427 exiting at the A6003 roundabout.
Traffic will continue along the A6003 (Uppingham Road) to its termination at the A43 roundabout.
Traffic must then access the A43 (southbound towards Kettering) and continue to Junction 7 where traffic will leave the A43 and join the A14 travelling westbound towards Desborough and Rothwell.
Traffic will then exit the A14 at Junction 3 to re-join the A6.
A Highways spokesman said: “We are working with all our partners to address this as quickly and efficiently as possible and will provide updates as we progress.
“The diversion follows the most appropriate route and is for all vehicles as there are weight restrictions which must be observed.”