Welwyn North Tunnel

The Welwyn North Tunnel and Welwyn South Tunnel are two railway tunnels on the East Coast Main Line between Welwyn North and Knebworth railway stations in Hertfordshire, England. They are 1,046 yards (956 m) and 446 yards (408 m) in length respectively, with an 11-chain (730 ft, 220 m) cutting between them. They each consist of a single bore, forming part of capacity problems on that section of the East Coast Main Line. They tolerate a speed of 115 miles per hour (185 km/h) on the Down Main track; the speed on the Up Main track is 125 miles per hour (201 km/h) in the North Tunnel and 105 miles per hour (169 km/h) in the South Tunnel. The tunnels were built in 1849–50 as part of the Great Northern Railway between London and Peterborough. The southern portal of the South Tunnel is highly decorated and was given Grade II listed status in 2000 alongside the adjacent Welwyn North railway station. In 1886, there was a three-way crash in the North Tunnel caused by a broken-down train whose driver did not follow correct procedures; it would later be described as "one of the most destructive in railway history". In the modern day, the tunnels are frequently discussed as part of capacity issues on the East Coast Main Line which limit the trunk route to only 18 trains per hour.

Tunnel data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).