12/04/2015 19:13 BST | Updated 12/06/2015 06:59 BST

Walkable Cities: Why London Needs a Garden Bridge

Cities must constantly adapt to stay alive. More people, more journeys and more density mean cities must reinvent themselves to remain pleasant places to be.

I have always been interested in improving public space. Public gardens are crucial but finding room for them is difficult in tightly-packed cities.

In 2012 an opportunity arose to try something radical. What if we could make space for an entirely new garden in Central London? What if that garden was by one of the world's greatest garden designers? What if it could also reduce pressure on London's transport system?

This is the opportunity presented by the Garden Bridge, a new public garden and pedestrian link across the Thames from Temple station to the South Bank, led by our client the Garden Bridge Trust. Throughout my time on the project working with the Trust and Transport for London I've been convinced it will offer huge benefits to the city around it.

TfL identified the need for more pedestrian crossings and by combining this infrastructural demand with an entirely new public space, London gets an amenity that works twice as hard.

The Garden Bridge will be a truly public space, free to all, without tickets or reservations. Year round it will stay open until midnight, much longer than most public gardens, and re-open at 6am. Concerns have been raised that it will become a venue for private entertaining, but planning conditions restrict closures to just 12 events to help cover maintenance costs per year.

I'm sympathetic to calls for a bike lane, but the Garden Bridge is all about making our city more walkable. An estimated 9,000 commuters will cross it each working day alleviating bus and tube traffic from Waterloo into the City.

Building in central London means respecting treasured vistas. During detailed design over 40 precise views were analysed, demonstrating the Garden Bridge will not negatively affect key protected angles. Some impact on the immediate embankment is unavoidable, but this is more than compensated for by the many new views the bridge itself will provide.

The fundraising target of £175million reflects the total cost including construction, land, VAT, fees, and an allowance for risk, inflation and contingency. Two thirds will be raised from private funds and £125million has already been pledged so far.

Support for the bridge has been overwhelming. Over 85% of respondents to the public consultation held by the Garden Bridge Trust are in favour of the project. Local consultation in Lambeth and Westminster has returned hugely positive responses, and both Boroughs, as well as the Deputy Mayor for Policy and Planning, have approved the planning proposal. English Heritage calls it 'a once in a generation opportunity'. Some local residents have raised objections on grounds of lost views, but as I've said these are more than compensated for.

I believe The Garden Bridge will bring a new layer of richness and beauty to the heart of our city. I hope once it is complete you'll enjoy using it as much as we have enjoyed designing it.