The Nickey Line (officially known as the Harpenden to Hemel Hempstead Railway) is a disused railway that once linked the towns of Hemel Hempstead and, initially, Luton but later Harpenden via Redbourn, in Hertfordshire, England. The course of most of the railway has been redeveloped as a cycle and walking path, and is part of the Oxford to Welwyn Garden City route of the National Cycle Network. It is approximately nine miles (14 km) long.