Buses will replace trains between West Kirby and Birkenhead North for the next two weekends as engineers replace a weak bridge.
Network Rail is spending £2.3m replacing the structure on Bridge Road.
The railway will be closed on the weekends of the 22-23 and 29-30 January.
Bridge Road is also currently closed to traffic, with diversions in place for motorists.
Kathryn Berry, scheme project manager for Network Rail, said: “The work at Bridge Road is essential to keep the bridge safe and reliable for road users and pedestrians above as well as rail passengers below.
“I thank passengers road users and local people in advance for their patience while we carry out this vital work.”
Emma Cowan, finance and transformation director at Merseyrail, said: “The refurbishment of this particular bridge is a vital piece of maintenance that helps to ensure the Merseyrail network remains safe for all that use it.
“We appreciate that this will cause some inconvenience for passengers who may need to use a rail replacement service whilst the work is completed, and we thank them for their patience and understanding while this vital work is carried out.
“Anyone wishing to travel on this line during these works is advised to check our website and social media before travelling for the latest updates on rail replacement services.”
Work to replace the bridge will take place during a combination of day and night-time shifts.
More information about the rail replacement is available at https://www.merseyrail.org/plan-your-journey/engineering-works.aspx