Campaigners and politicians are calling on Network Rail to spare South Fylde commuters months of misery during vital upgrade work.
The route to Blackpool North is expected to close for up to 18 weeks in winter 2017 for conversion to electric power.
However, The Express understands Network Rail is considering options to keep the Blackpool South route open.
The line, which runs through Kirkham, Moss Side, Lytham, Ansdell and St Annes currently has significantly limited capacity.
There are no signals along the single track section which can only accommodate one train per hour.
Campaigners say a loop, allowing trains to pass, would double capacity on the branch, making it a viable alternative to Blackpool North during next year’s planned blockade.
Paul Nettleton of Blackpool and Fylde Rail Users Group said: “It is good that Network Rail is considering using the South Fylde line to retain some rail link.
“It is likely both routes will have to close at some point to allow works to take place at Kirkham.
“However, it could serve as a lifeline during the planned closure.
“Currently there is only capacity for one train per hour.
“A passing loop would double that frequency and with longer trains the operators might be able to better match the current capacity.
“The North West electrification project is costing more that £1bn and the cost of a loop would be just a tiny fraction of that.
“But it would make a difference not just during any closure but into the future.”
Network Rail is understood not to be considering a passing loop at this stage.
However the firm is considering how the line might accommodate longer trains, with Network Rail keen to find options other than rail replacement buses.
Fylde MP Mark Menzies backed efforts to retain the South Fylde route and made clear he has already been pushing for increased capacity
He said: “I am a big supporter of the Blackpool South line and have had numerous conversations with the Transport Secretary about installing a passing loop on the line to allow more trains to operate along the route.
“With the Blackpool North line being closed for electrification it is vital that people are still able to access the Fylde coast by rail and I would support any efforts which encourage visitors to use the remaining route.
“I have always felt that the line is under-utilised and with the correct investment could be a fantastic asset to the area.
“That investment could also include a link up with the Blackpool Tramway – which has been one of the big success stories in public transport recently – to bring trams through to Lytham.”
Network Rail has not yet confirmed the dates for any planned closures.
However in a briefing for The Express, officials revealed some of the proposed works which will take place alongside electrification.
They include a new platform and new track alignments at Kirkham and Wesham, allowing Blackpool South-bound services to be separated from main line traffic.
The number of platforms at Blackpool North is set to be reduced from eight to six, with some extended to accomodate longer trains.
Victorian-era signalling between Preston and Blackpool will also be replaced, with five signal boxes, including those at Kirkham and Salwick closing.
Although the improvement work has been widely welcomed, some concerns have been raised over a loss of flexibility.
Mr Nettleton is particularly worried that lines at Kirkham which allow fast trains to pass slower services will be removed.