London is a city synonymous with innovative infrastructure. The capital has prospered on the shoulders of great pioneers of engineering such as Marc Isambard Brunel and Sir Joseph Bazalgette, responsible respectively for the first Underground rail line and London’s elaborate sewer network.

Building on Brunel’s success, the capital is home to the first metro system of its kind: the Tube now sees up to five million passenger journeys every day, and from Brussels  to Beijing it has been the blueprint for hundreds of other cities to follow as they have developed their own versions. Likewise, Bazalgette’s sewer system was considered forward-thinking, having been built to accommodate population growth from three to four-and-a-half million people. It now serves as many as eight million.

It’s therefore no surprise that as we developed our recommendations for improving transport within cities across the country, we turned to London for inspiration. While facing a fiscal remit of no more than 1.2% of GDP and limiting the impact on bills, we are still arguing for local leaders to benefit from £43bn on top of current spending levels up to 2040, so they can develop long-term integrated transport strategies that boost job opportunities and deliver much-needed homes.

But as we enter another chapter in the history of the capital’s infrastructure, it is paramount that we maintain, or even enhance, this world-class legacy. Although the construction tools and techniques have come some way in the last century, our ancestors would know well the challenges we face of congestion and capacity. As London’s population continues to grow, ever greater demands are placed on its infrastructure.

Crossrail – the Elizabeth Line – will help to relieve this strain when it comes on stream. It will make it easier for travellers to get from Reading and Heathrow in the west to Shenfield and Woolwich in the east, intersecting key stations in the heart of Central London including Paddington, Tottenham Court Road and Liverpool Street.

Colossal though Crossrail is for London, this project alone is insufficient to solve the city’s congestion problems. To unlock its full potential, the capital needs Crossrail 2 – which would enable better links from Hertfordshire in the north to Surrey in the south. The proposed route would tackle congestion in some of our busiest stations, including King’s Cross, Victoria and Clapham Junction. Crucially, it would also support the delivery of as many as 200,000 of the new homes that London desperately needs. The government must prioritise the funding that is necessary to get this project off the ground.

The Commission indicated our strong support for this vital project in our National Infrastructure Assessment, published last July. The first of its kind, it looks three decades ahead and sets the strategy for meeting future needs in digital communications, transport, energy supply, tackling waste, our water supplies, and managing flood risk.

The capital benefits from an integrated transport system, devolved powers and a thriving economy. We want to see other cities being given this opportunity, which is why we recommended that the government provide additional powers to enable metro mayors and other local leaders to develop long-term transport strategies that create job opportunities and deliver homes in their local communities. Central to this is Northern Powerhouse Rail, which will help to improve journeys between cities across the north of England and allow the country as a whole to make the most of HS2.

However, as we ameliorate transport for cities around the country, it is important that this does not come at London’s expense. It is vital for our continued economic success that we keep London moving and capitalise on the progress that has already been made. Doing so requires making bold choices today.

This article first appeared in Rail Technology Magazine