Provisions are being made for a third set of rails to be laid on the Brighton to London mainline.
A new footbridge over the line at Keymer Junction, Burgess Hill, has been designed with enough space to allow for the extra tracks, it has emerged.
However, Network Rail has played down the news, adding that there are no immediate plans for extra rails.
The blueprints for the bridge between Wivelsfield and Burgess Hill stations were revealed in a report to be considered by West Sussex County Council.
The document suggests leaving enough room for the third set of rails on the stretch.
The additional rails would improve the Brighton to London service as well as allowing trains to merge from the Eastbourne line.
A report to the South Mid Sussex County Local Committee, confirmed the progress of the bridge.
It read: “Following the review of the report in the New Year, West Sussex County Council will commission the next stage of the design process and the relevant surveys.”
Work on the bridge is expected to begin in early spring with the new structure scheduled to be in place in late 2014.
The new bridge, which will be part funded by £250,000 from section 106 payments, is designed to improve local connections.
Network Rail confirmed that provisions were being made for a third set of rails.
However a spokesman played down any immediate plans citing the significant cost and the possibility of needing extra land.
He added: “There are currently no plans for additional tracks on the Brighton Main Line, which the new bridge will span.
“However the design of the bridge at Keymer Junction is such that it would not preclude construction of a third track in future.”
Southern, which also runs services on the line, was named seventh worst.
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