Postscript description
Mechanical signalling has been on the way out since colour signalling was introduced in the 1920s. It was originally intended to replace mechanical signalling by the millennium, however, there are still odd pockets in the system today. There is a network rail project to finally eliminate the last boxes and mechanical signals in the next few years, replacing it with a dozen railway operating centres. this book looks at the last mechanical signalling on the network.
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