The World Metro Figures report reveals that, of the 156 metros in operation around the world in 2014, almost two thirds are in Europe and Asia, and nearly half of all metros are located in Asia.

Tokyo's metropolitan area has the busiest metro network in the world, with almost 3.6 billion passenger journeys per year - a 10% increase in ridership since 2012.

Chinese metro systems have also seen significant growth. Beijing metro, the world's second busiest metro, has seen a 39% growth in ridership to 3.4 billion passenger journeys per year. Shanghai metro ridership has increased by 25% to 2.8 billion passenger journeys per year, making it the third busiest metro in the world. Seoul and Moscow have the fourth and fifth busiest metro networks, with 2.6 and 2.4 billion passenger journeys per year respectively.

Asian cities are also home to the world's longest metro networks, with Shanghai and Beijing top of the list with 548km and 527km, respectively, while London comes in at third place with a network totalling 436km.

The report also found that nearly a quarter of the world's metros have at least one fully automated line. There are currently 732km of automated metro lines in 35 cities around the world – Dubai, Vancouver and
Singapore have the longest automated lines at 80km, 68km and 65km, respectively.

"Cities have always been at the core of growth and development and will continue to be the main engine of economic activity, entrepreneurship and creativity," says UITP secretary general Mr Alain Flausch.

"To fully reach this potential, we need to make sure people move seamlessly and can both access and contribute to the wellbeing of their cities. Metros play an instrumental role in helping cities to achieve their potential in today's fast-changing world."