The A272 will close at Langrish near Petersfield for six weeks from Monday 1st September for essential maintenance work on the historic Petersfield Road Bridge.
National Highways has announced the closure will remain in place around the clock whilst crucial repair works are carried out on the century-old structure.
Motorists will find signed diversion routes operating throughout the closure period. Heavy goods vehicles and larger commercial vehicles are strongly encouraged to follow the official diversion rather than attempting to use minor roads unsuitable for their size.
The designated diversion route will direct traffic along the A272, A3, A325, A31 and A32.
Motorists are urged to plan their journeys in advance and factor in additional travel time during the six-week closure period.
The bridge carries significant historical importance, having been built approximately 1903 as part of the then-new Meon Valley railway line. This cross-country rail route stretched 22 miles, connecting Alton with Fareham.