The closure to the Desborough bypass section of the A6 will be extended beyond the end of April as the damage is worse and repair work more complicated than initially thought.
However Northamptonshire County Council will now trial re-opening the southbound lane of the A6 from Braybrooke Road to the A14 to relieve some of the traffic pressure in Desborough and Rothwell. This opened on Thursday 23 March after the morning rush-hour.
The problems found on the carriageway leading on to the railway bridge are more severe than at the River Ise Bridge and there are logistical problems of carrying out repairs over a live railway line.
Because of these complications the work will not be completed until after the School Summer Holidays. However every effort will be made to get the works done as soon as possible.
Cllr Ian Morris, county council cabinet member for transport, highways and environment, said: “Extensive survey work has been carried out and carrying out repairs on the road where it joins the railway bridge is much more complicated than initially thought.
“We have no option but to keep the closure in place for longer than we initially anticipated so that the work can be done properly.
“We are aware of the effect that the closure has had on the local community and that is why we have decided to trial the opening up a section of the A6 in an attempt to alleviate some of the traffic pressure.
“We would like to thank people and businesses in the local communities for their patience while this situation continues.”
The county council is working with all associated parties and is identifying any funding available nationally for unusual situations such as this.
The works require significant collaboration and coordinated planning because of the proximity to the Midland Mainline.
The application for permission to work alongside the rail line has been submitted to Network Rail and this process will take time to agree and put in place as we are working to minimise the impact.
The main diversion route via the A14, the A43, A6003 and the A427 is still in place.
A section of the A6 bypass was closed from 18 January after a routine inspection showed there were faults under the carriageway on the approaches to the River Ise bridge. Works have been completed to repair this section of the road.
Further investigation showed more faults on the approaches to the rail bridge on the stretch of the A6 between Braybrooke Road and B576, where it runs over the railway line.
On 20 February the closure was extended. Since then the A6 has remained fully closed from junction 3 of the A14 through to the B576.