An outline business case for final proposals to improve a major bottleneck on the region's railways is expected to be submitted next spring.
Improvements to Ely North junction could unlock half-hourly trains between King's Lynn and London.
But while the issue has been on the agenda for some years, it has not yet progressed beyond the drawing board.
Network Rail launched its second round of public consultation to increase rail capacity through Ely in May.
The operator says the system is operating at full capacity which is "limiting the opportunity for growth of important routes for passengers and cross-country freight services".
It said the railway, which includes a busy junction where five lines converge, must be upgraded to allow more trains to pass through. It is where lines from north, south, east and west all meet, including services to and from King’s Lynn.
The Ely area capacity enhancement (EACE) programme could see speedier service in the Eastern region with more frequent trains.
The current rate of 6.5 trains per hour in each direction at off-peak times could be enhanced to 10 per hour, including extra trains between King's Lynn and London.
Members of the Fen Line Users Association (FLUA) and South West Norfolk MP Liz Truss are among those involved in the project.
John Grant, FLUA chair, said the group's main ambition is for a half-hourly service to King's Lynn but that they will be pressing for a greater increase in capacity than what the current proposals would bring.
He added: "Currently there are two fast trains per hour between Cambridge and London King's Cross, and they both serve the Fen Line stations as far as Ely, but only one goes all the way to King's Lynn.
"There was a commitment in the Great Northern franchise agreement that both would do so, but it hasn't been possible because of capacity restrictions through Ely North junction.
"They are barely enough to support current requirements, in the longer term a service every 15 or 20 minutes to King's Lynn may be needed, along with more frequent services to Norwich and to the Wisbech area, much of which is in west Norfolk."
The chair said a half-hourly service would make travelling by rail a "more attractive alternative" to the car and give people in west Norfolk easier access to Cambridge and London.
Ms Truss said a further £13m has been committed to develop the programme, with passengers already seeing improvements to trains in 2020.
She said: "The government invested £27 million last year upgrading the Fen line in order that longer trains can operate on the route and this has been especially welcomed by rail commuters frustrated by over-crowding.
"A number of key rail routes, including freight traffic from Felixstowe to the Midlands and beyond, cross the congested Ely North junction so unlocking this bottleneck is a priority and throughout the Covid pandemic teams from DfT, Network Rail, Highways and local councils have been working to develop the scheme.
"It is extremely complex with road layout and 43 level crossings all needing to be upgraded.
"Once work is completed the junction will allow for half-hourly services on the King's Lynn to London line and increased services via Thetford.
"I continue to work with colleagues, DfT, Network Rail and local councillors to ensure this significant project is fully progressed and expect the outline business case to be submitted in Spring 2022."
Great Northern and Network Rail increased the capacity of its trains by doubling their lengths in December, which GN said has made a huge difference for passengers on the route.
Previously services for all stations to King's Lynn had only four carriages beyond Cambridge, and trains turning around at Ely had eight carriages but could not stop at Waterbeach.
The six-week consultation, which ends on July 4, includes changes to track and platforms at Ely station, upgrades for bridges and a level crossing closure.
Further public consultation is planned later in 2021 over the remodelling of the track layout at Ely North junction.
For more on the consultation visit www.networkrail.co.uk/Ely
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