in 1872, the ner gained parliamentary powers to construct a line from bowesfield junction (where it joined the route of stockton & darlington railway) to wellfield junction (on the route of the hd&r, just to the south of the future wellfield station) (known as the castle eden branch line) and opened the line in stages, with the section north of carlton junction (where the line crossed the route of the clarence railway) opening to freight traffic on 1 august 1878. this new line provided an alternative route from teesside to the north, bypassing hesleden bank. local passenger trains were eventually introduced on 1 march 1880, utilising the former clarence railway route from stockton-on-tees station to reach carlton junction before taking the new line to wellfield junction and initially continued over the route of the hd&r to thornley station. two years later wellfield station was opened, a short distance to the north of the junction, primarily as an interchange station to allow passengers from the line to stockton to connect with trains to sunderland and hartlepool.