Geograph - photograph every grid square

Signalboxes are used in Britain to control the safe movement of trains across the railway network. Most are located either just outside stations or at junctions.
Wikipedia: Link

The Cambridge Line runs from Cambridge Junction on the East Coast Main Line to Shepreth Branch Junction on the West Anglia Main Line and forms part of the route between London King's Cross and East Anglia. The line opened in 1851.
In 2013 the Hitchin Flyover was completed to allow better access across the East Coast Main Line.