A stretch of the A6003 will close this weekend for the first stage of works to replace the railway bridge.
Work to replace the railway bridge just off the A43 roundabout has been in the offing for some time.
As part of these works the A6003 will close just after midnight on Saturday, February 4, and re-open on Monday, February 6.
But with the A6 near Desborough shut until the end of February, the A6003 is already acting as a diversion route - meaning there will be a diversion to the diversion.
Traffic will be taken down the A43 Corby Link Road on to the A427.
A Northamptonshire County Council spokesman said: “The county council makes every effort to keep the highways network as freely flowing as possible and minimise the impact of work on the travelling public.
“The works on the A6003 by Network Rail have been planned for some time and have been scheduled to minimise disruption.
“The works will generally take place at weekends, when traffic volumes are at their lowest.
“These are major works to replace the railway bridge, which are part of a much wider scheme on the busy railway network.
“The first set of works start this weekend at just after midnight on Saturday, February 4, and will continue until 6am on Monday, February 6.
“A signed diversion route will be in place taking traffic on the A43 Corby Link Road to the A427.
“The closure of the A6 near Desborough had to be done as an emergency safety measure due to unforeseen circumstances and needs to remain in place until the end of February.”