The Tees Valley Line is a rail route, in Northern England, following part of the original Stockton and Darlington Railway route of 1825. The line covers a distance of , and connects to via , and 14 other stations in the Teesdale. The section of line between and is branded as The Bishop Line, and is supported by the Bishop Line Community Rail Partnership. Beyond the line's western terminus at Bishop Auckland, the tracks continue for around to along what is now the Weardale Heritage Railway. Service Services on the Tees Valley Line are operated by Northern Trains, with an hourly service running between Saltburn and Bishop Auckland, and half-hourly trains to Darlington. Additional Northern Trains services operate along the Tees Valley Line during the morning peak, with some journeys between Middlesbrough and Newcastle running along the East Coast Main Line, rather than the Durham Coast Line. TransPennine Express also operate along part of the Tees Valley Line, with hourly services from Redcar Central and Middlesbrough to York, Leeds and Manchester Airport. Predominantly, rolling stock on the Tees Valley Line consists of Class 156 and Class 158 diesel multiple units operated by Northern Trains, as well Class 185 diesel multiple units operated by TransPennine Express. The Class 156 and 158 units operating on the Tees Valley Line are currently in the process of being refurbished, with upgrades including free WiFi, power sockets, on-board passenger information displays, and an interior refresh. Class 185 units operated by TransPennine Express were refurbished as part of a £32 million investment, with the work being completed in 2018. Class 142 'Pacer' trains also served the line on Northern services, until the turn of the new decade, when they were withdrawn from passenger service. The route serves the following stations: Bishop Auckland, Shildon, Newton Aycliffe, Heighington, North Road (Darlington), Darlington, Dinsdale, Teesside Airport, Allens West, Eaglescliffe, Thornaby, Middlesbrough, South Bank, Redcar Central, Redcar East, Longbeck, Marske and Saltburn. History The section of line between Bishop Auckland and Darlington (prior to joining the East Coast Main Line), as well as the section between Dinsdale (near Middleton St. George) and Eaglescliffe, follow the original route of the Stockton & Darlington Railway, which dates back to 1825. The line from Middlesbrough to Saltburn, as well as the freight only line to Boulby Mine, were part of the Whitby, Redcar & Middlesbrough Union Railway, until the line's closure on 5