The latest stage of work to upgrade the East Coast Mainline through Peterborough to allow more freight services to run has been completed.
Network rail has finished the signal system in the newly constructed tunnel at Werrington.
Ground-breaking new technology was used to push the tunnel into place back in January.
Testing will now take place to make sure it is ready for freight trains to use this winter.
It will mean they can be diverted under the east coast mainline to cut congestion.
Work began onsite at Werrington in Summer 2018.
The ground-breaking 11,000-tonne tunnel, built onsite as trains continued running on the East Coast Main Line , was pushed into place using innovative construction techniques in January 2021.
Teams then installed around 8km of track in the area which runs through the new tunnel.
Over the summer, work has been completed to connect the new track to the existing Stamford lines and put signalling equipment in place.
Vital work to test the new tunnel will now take place with trains expected to begin using it by the end of this year.
Network rail says diverting freight trains underneath one of the busiest routes in the country will mean faster, more reliable services for both passengers and freight.