[2] The line covers a distance of 38 miles (61 km), and connects Bishop Auckland with Saltburn via Darlington, Middlesbrough and 14 other stations in the Teesdale.

[4] Beyond the line's western terminus at Bishop Auckland, the tracks continue for around 16 miles (26 km) to Stanhope along what is now the Weardale Heritage Railway.

[5] The section of line between Bishop Auckland and Albert Hill Junction, Darlington (prior to joining the East Coast Main Line), as well as the section between Oak Tree Junction, Dinsdale (near Middleton St. George) and Eaglescliffe, follow the original route of the Stockton & Darlington Railway, which dates back to 1825.

[6] In March 2015, a 0.62 miles (1 km) electrified siding was laid adjacent to the Tees Valley Line, just south of Heighington.

This allows low-speed testing of the trains manufactured at the nearby Hitachi Rail plant at Newton Aycliffe, including TOPS classes 800, 801, 805, 807, 810 and 385.