In 2012, Dubai Metro made it into the Guinness Book of World Records as the world’s longest driverless metro network. It has since lost that title but remains a pioneering project with more than 160 million passenger journeys a year. To date, two lines are operational. The system is mainly above ground, with about 10 kilometres underground.

The Red Line is 52km long, covering the length of Dubai, from Jebel Ali in the south to Rashidiya in the north. The line cost $3.8bn to build, with construction beginning in August 2005. The main contractor was a consortium led by Japan’s Mitsubishi. France’s Systra and the US’ Parsons International oversaw construction. The line was opened for public use on 10 September 2009.

The 22.5km-long Green Line, completed in 2011, also cost $3.8bn. The winning contractor was again a Mitsubishi Corporation-led consortium.The Blue, Purple and Gold lines remain at the study stage. They will be joined by the Pink Line, which has an expected tender date of 2024. Dubai is pushing ahead with a $2.9bn extension to the Red Line, as part of its Expo 2020 plans and is expected to tender a $500m extension to the Green Line during 2017.