V/LINE will offer free train and coach travel on the Gippsland line until further notice.
Coaches will replace trains between Moe and Traralgon for a few weeks while V/Line carries out planned replacement of under-track pipes at the Morwell River.
Corrosion of the four corrugated steel pipes has brought forward the need for the works, which will require temporary closure of a short section of track.
V/Line chief executive Theo Taifalos said once works were completed, the current 30 kilometre an hour train speed restrictions would be lifted and the line speed of 160kmh could be resumed, making for faster and more reliable trains.
Mr Taifalos said it was hoped the bridge renewal works could be done in December, but the safety of customers and staff came first.
"The uniform thickness of the corrugated steel has deteriorated and the culverts should be replaced before there is any safety risk," he said.
"The replacement of these pipes is part of an ongoing maintenance program to ensure our rail infrastructure continues to meet or exceed safety standards.
"Work crews will be on site from this weekend to prepare the site for construction, including making space for a 600 tonne mobile crane to lift 23 metre bridge spans into place."
The new section will be supported by 32m concrete piles on either side of the culverts, with reinforced abutments and spans to ensure a sturdy independent structure.
Mr Taifalos apologised for the inconvenience and short notice for customers.
"We will do everything possible to minimise inconvenience to our customers, including placing extra customer service staff at stations to assist those customers who need it," he said.
"Rest assured we have a comprehensive coach plan in place to get our customers to their destinations. Our trains will run between Melbourne and Moe and between Traralgon and Bairnsdale in both directions.
"The $4 million works will create a strong, long term solution to this crossing of the Morwell River."
Customers from Traralgon and Morwell will need to depart by coach 15 minutes earlier than the normal timetable to meet the scheduled train out of Moe.
Some services from Bairnsdale will have a direct coach from Traralgon to Melbourne.
V/Line will be working closely with Public Transport Victoria to ensure customers are kept informed about the impact on their travel and any ticketing-related issues.
For travel updates or for customers with special needs, phone 1800 800 007. For the latest information visit vline.com.au/gippslandline or follow @vline_gippsland on Twitter.