Proposals for a £40million project to dual part of the Felixstowe to Ipswich rail line to take more freight and remove lorries from Suffolk’s roads is under review.

The scheme was put forward by the Port of Felixstowe as part of its southern expansion plan and was said to be needed to increase capacity on the line by 300,000 containers a year on new train services.

But the project was not carried out in the first phase of the expansion – and now there is uncertainty over whether it will ever be done.

The work would have seen four-and-a-half miles of track dualled between Trimley station and Nacton.

Suffolk Coastal councillor Richard Kerry, a member of the Port of Felixstowe Local Authority Liaison Committee, said: “The original proposal for dualling a section of the line is being reviewed by Network Rail.

“The obligation dates from conversations and impact studies undertaken ten years ago.

“Those studies did not foresee the use of 30-wagon trains – or as many as the 30 services already operating in 2013. In actual fact, the rail capacity that now exists through using longer trains is already equivalent to that which the partial dualling was due to deliver in terms of the number of wagons per day.

“The world – and the railway network in particular – has moved on considerably since 2004 and, as a consequence, Network Rail is undertaking design development work over the next 12 months with the view to finalising the details of an appropriate ‘fit for purpose’ scheme in 2014.

“This may not be the same as that which they thought was right for 2004.”

Opening of a third rail terminal though has added capacity for another 750,000 boxes a year by rail.