London's transport network has been hailed as "world-class", but it could easily lose this prestigious status if investment dries up.

This is the main conclusion from a new report commissioned by Siemens, which was based on data gathered from a survey of more than 3,500 London transport professionals.

It suggested that the capital's transport infrastructure is currently in a very healthy state, although there is still plenty of room for improvement, especially when it comes to cycling safety and air pollution.

Professor David Begg - who led the study - confirmed that 73 per cent of the respondents felt London's infrastructure was either excellent or very good.

"Continued investment in London's world-class transport system is imperative to prevent any decline," he remarked.

There are no signs to suggest funding may suddenly fall by the wayside, as major developments such as the Crossrail and Crossrail 2 projects are already making excellent progress.

The former is set to cost around £14.5 billion and is expected to open in 2018.