One of the key capacity issues for the network is accommodating the mix of inter-city passenger and freight on the two-track sections of principal main lines. The decline of coal movements has eased this problem on some sections of route, for example the East Coast main line between Newcastle and Edinburgh. Some years ago, this was close to being a desert for freight, then movements of imported and opencast coal to the Yorkshire power stations ramped up, and the route became busy with a toxic mix of 60mph bulk coal trains and inter-city expresses; but the former have virtually gone, and there’s not much other freight. This is just as well, as there are now generally three inter-city trains an hour, which will rise to four when TransPennine Express starts regular operation to Edinburgh on this route. Further south, the most constrained section was probably Peterborough – Doncaster, 52 miles of which, from Stoke Junction to south of Doncaster, is double track, with five loops northbound, six southbound, and five or six 125mph trains in each direction. There is now a lot of freight on this axis too, mostly intermodal, typically between Felixstowe and Yorkshire, but ranging from Class 6 sand trains to Royal Mail EMUs.