These line diagrams portray the NER’s Darlington and Tebay line, Tees Valley Branch to Middleton-in-Teesdale, plus the Forcett, Forcett Quarry, Merrybent and Barnard Castle Goods branches. Envisaged as a branch the Darlington and Barnard Castle Railway opened on 8th July 1856 being worked by the Stockton and Darlington Railway from the start. The terminus at Barnard Castle became goods only as the South Durham and Lancashire Union Railway line to Tebay, opened on 4th July 1861, made a junction further to the east. The line quickly assumed an important role in cross Pennine communications, primarily for freight and mineral traffic (particularly coke and iron ore) rather than passengers. It had taken the SD&LUR four years to complete the 35 mile link with its extensive engineering works including the many fine bridges illustrated on the diagrams which follow. The Tees Valley Railway to Middleton-in-Teesdale, opened on 11th May 1868, had hoped to join up with the Alston Branch but the line was not a financial success though large stone quarries were established at various points. Between Barnard Castle and Darlington two freight and mineral branches went off to the south; the Forcett Railway, opened in February 1867, and the Merrybent branch, opened on 1st June 1870.