The railway line between Brockenhurst and Lymington Pier will be closed for planned upgrades over the festive period.
The line will be shut off from December 22, with services resuming on January 6, according to Network Rail.
Buses will replace trains during this time.
The second phase of the work will see the bridge over the Lymington River strengthened, along with repairs to the Lymington Viaduct.
"The heavily corroded critical steel elements" of the viaduct will be refurbished, and the wheel timbers, which support the track, will be replaced.
The track over Lymington Town Level Crossing will also be replaced. As a result, the level crossing will be closed to road traffic on December 29.
A temporary bridge will be built near the crossing for passengers. South Western Railway’s rail replacement service will call at Lymington Town only in the Brockenhurst direction.
A shuttle bus will run between Lymington Town and Lymington Pier. Additional improvements will be made on Christmas Day and Boxing Day when no passenger services are running.
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Mark Goodall, Network Rail's Wessex route director, said: "We appreciate that there is never a good time to close the railway, however we know that fewer people travel during the festive period so this is the least disruptive time to complete these important upgrades.
"Once this work is completed, passengers using the branch line will benefit from smoother and more reliable journeys.
"We have been working closely with our partners South Western Railway and Wightlink to ensure passengers travelling between Lymington and Newport, on the Isle of Wight will have minimum disruption during this period."
These include enhancements to Brockenhurst Level Crossing and tamping, which involves compacting the ballast underneath the tracks, across the junctions at Brockenhurst station.
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