Keeping Trade on Track said the upgrade to Ely junction in Cambridgeshire would also double passenger services on the Ely-Kings Lynn and Ipswich-Peterborough routes.
The new report, released by the two main bodies that study transport issues in the East of England, is another attempt to persuade the government to upgrade the bottleneck.
The report focuses on the impact of rail freight and describes the line from the Port of Felixstowe in Suffolk to the Midlands and North of England as the most intensively used and nationally important rail freight corridor on the network.
The new junction would allow six additional freight trains a day to use the line, the equivalent of 450 lorries stretching more than six miles.
Network Rail said the junction signal and level crossing improvements would take six years to deliver, but the report said the work would deliver a high cost-benefit ratio of 4.89 for every pound invested, and it would also reduce carbon emissions.
I am told ministers and officials at the Department for Transport get the argument, but the Treasury is worried about the cost.
The government has announced the final route for the East West Rail route, which runs from Oxford to Cambridge, and has confirmed funding for a new Cambridge South station.
The rail minister said there were more spending announcements to come and people should be patient, but he warned that funds were not unlimited.
A significant part of the programme will be spent in Cambridge and we have to measure an approach across the country as a whole. The scheme is a vital hub for the economies of the Midlands and North and offers substantial potential to alleviate congestion on strategic roads while reducing emissions caused by HGV journeys which could more accurately be made via rail.