The terrain crossed at the Nottingham end of the line was exceptionally difficult, and costly, but it undoubtedly paid off, as lucrative coal traffic expanded enormously. Colwick was made a distribution and marshalling centre for the GNR's Derbyshire colliery traffic. A large group of sorting sidings were installed, and engine shed and wagon repair facilities; the Colwick yard was expanded repeatedly over later years, eventually having a capacity for 6,000 vehicles. The GNR had given the London and North Western Railway running powers over the Derbyshire lines, and this proved extremely profitable for the LNWR, which made a connection over the Great Northern and LNWR joint line.