The service, announced in July 2010 and estimated to cost £60 million, comprises a gondola line that crosses the Thames from the Greenwich Peninsula to the Royal Docks. Construction began in August 2011. The cable car is based on Monocable Detachable Gondola (MDG) technology, a system which uses a single cable for both propulsion and support, such as that used on the metrocable in Medellín, Colombia. The MDG system is reportedly cheaper and quicker to install than a more complex three-cable system which would allow for larger-capacity cars.