Ever noticed the whopping great width of the southbound platform at Angel tube station? Passengers are allocated around twice as much space as the trains, in marked contrast to other stations where it's more like 50/50. A similar thing happens at Euston.
The reason is simple. Angel and Euston used to have island platforms, as still sported at Clapham Common and Clapham North stations.
Such a set-up just about functions in Clapham, but was a major headache at busier Angel and Euston. The narrow waiting space — just 3.7m — soon became overcrowded and potentially dangerous.
Both stations were reworked: Euston during the construction of the Victoria line in the 1960s, and Angel in the early 1990s. In each case, one side of the island platform was filled in, creating a double-width platform. Trains were diverted into a newly excavated section of running track.
At Angel, the major engineering didn't stop there. The unreliable lifts (brilliant video) were removed and a new station entrance was built on Upper Street, some distance from the original entry on City Road. This required a set of extra-length escalators, which remain the longest on the network... and made this possible:
