The last of the independent railways that became part of the modern DCL was the Londonderry, Seaham & Sunderland Railway of 1854, constructed, primarily, to enable coal traffic from the extensive Londonderry Railway colliery railway network to be diverted from Seaham Harbour (which had become unable to handle the large volumes of coal passing through it) to the recently constructed South Dock at Sunderland and thus followed route which parallel the D&SR north of Ryhope. Like the rest of the railways discussed here, the LS&SR later introduced a passenger service on 2 July 1855 between Seaham and Hendon Burn.