Werrington Dive Under is a replacement dual track grade separated railway junction at Werrington Junction north of railway station in Cambridgeshire, England. The junction leads to the Great Northern/Great Eastern Joint line which goes through to and beyond. Due to be completed in 2021, the dive under will allow trains on the west side of the East Coast Main Line to access the GN/GE line without conflicting with the faster passenger services on the ECML. The dive under will be constructed by a jacked deck on slide paths installed in access tunnels, a curved 'jack deck is pushed into place beneath the main running lines on the ECML. It will be the first use of a curved 'jack deck ' structure in the United Kingdom.The installation uses a patented method
Current junction
When the line closed between and Spalding in 1982,, freight traffic, instead of cutting across the western edge of the Fens, was diverted through Peterborough station. Trains therefore now have to use Werrington Junction for access to/from the GN/GE line. The junction is located north of Peterborough railway station. In order to use the junction, trains have to cross the lines used by the fast ECML passenger services on the level and in the case of trains to Spalding, also use the Up Fast line for 3 miles between Peterborough station and the junction. This can cause delay to fast passenger trains. Railtrack, Network Rail's predecessor, recognised that the ECML was congested and so upgraded the GN/GE line to accommodate the heavy container trains to and from the east coast ports. However Werrington Junction was still a significant bottleneck.
Proposed junction
In 2016, Network Rail submitted a Transport and Works Act Order to the Secretary of State for Transport to build either a flyover or a dive-under the fast lines north of Peterborough to allow passenger and freight trains to access all lines without impacting upon other faster services. In summer 2018, Chris Grayling approved the order after a public inquiry favoured the dive-under option over the flyover. Initially, costings were estimated to be in the region of £100 million; but the agreed cost on approval was £200 million. The project will see the construction of of new line that will run underneath the fast lines, culverting works on Marholm Brook and the movement of the lines westwards over the culverted brook. This will mean that trains for the GN/GE line no longer need to cross the fast lines on the level, nor use the Up Fast line between Peterborough station and the junction. The project, coupled with other ECML improvement schemes will improve capacity on the line through Peterborough by 33% according to Network Rail. This equates to two extra train paths an hour by 2021, when the work is scheduled to be completed. In turn, this will remove 21 minutes from the fastest to service, and 13 minutes from the fastest King's Cross to service. It will also see an increase of 1,050 'intercity' seats per hour on express trains through Peterborough. The Spalding and Peterborough Transport Forum claimed that increasing the number of freight trains operating through Spalding would cause the level crossing barriers in the town to be down for 24 minutes of every hour. The Campaign for Better Transport praised the works and stated The construction will involve use of the UKs first curved box jack, which will consist of ten sections joined together, creating a curved box. The contractors expect to remove of earth and the box will weigh.
