The road will be closed in both directions between the B4371 at Church Stretton and the junction with the A5 near Shrewsbury from 8pm to 6am both nights.
Northbound traffic will be diverted via the B4371 and A458 to the junction with the A49 and A5. Southbound traffic will be diverted along the A5, the A458 and B4368 to rejoin the A49 at the Craven Arms.
Road users are advised to allow extra time for their journeys and to familiarise themselves with the diversion if they are intending to use the A49 on either of the two nights.
Members of the public should contact the Highways Agency Information Line on 0300 123 5000
Journalists should contact the Highways Agency press office on 0844 693 1448 and use the menu to speak to the most appropriate press officer