A garden over the Thames is a tantalising vision, but it's one that does not require an entirely new bridge. We could simply use one already there.

London's proposed Garden Bridge, a pedestrian link over the River Thames from Temple Station to Southbank is hoped to be a verdant pleasure corridor. It aspires to be an iconic addition to the riverside cityscape of London. It has, however, not been without controversy. The intention behind the bridge is a noble one, but the widespread concerns about cost, ownership and appropriateness are hard to ignore.

As architects and neighbours, we've been following the debate. It's led us to think about another bridge in the neighbourhood - Blackfriars Bridge, around the corner from our studios. There has been a crossing here since the mid-18th century. The latest incarnation, the work of James Cubitt, went up in 1869 in the thick of the Victorian apogee.

The bridge has served London well. We've looked a bit closer and we see an opportunity for it to rise to a new challenge. Re-thought and slightly re-adjusted, Blackfriars can accommodate a through public garden of similar size of the proposed Garden Bridge, while still providing the vital north-south link for vehicular and cycle traffic along the Blackfriars Rd - Farringdon Rd axis. By consolidating both the east and west pavements into one larger 14m-wide pavement on the west side, we could create a brilliant pedestrianised garden. The existing route has dramatic views of St Paul's and the City to the east and Westminster to the west. Existing parapets provide lovely seating nooks, riverside alcoves for a sandwich at lunchtime, a break from a job or a place for families to gather - a garden for morning commuters as well as the quiet moments of urban life.

Blackfriars Bridge Gardens celebrates our infrastructure heritage. It does not require extensive construction and can be delivered at a fraction of the cost of a new bridge. It would provide 40,000 sq ft of new green space. It would remain public and accessible to all, seamlessly integrated into the existing public realm on both sides of the River without obstructing any of its view of St Paul's. This light touch approach would be carbon neutral, and together with the cycle superhighway and solar panelled roof of Blackfriars Station, would be at the heart of a global exemplar for sustainable infrastructure.

'The original vision of the Garden Bridge was to deliver a garden on top of the River. The bridge is just a carrier of that vision, not the vision itself', says partner Artur Carulla

The practice has offered this proposal up as an open source proposition for the public. Speaking to Building Design, Artur suggests that 'It is the bridge that attracts all the criticism - over cost and procurement - which is a pity because there's some merit to the idea of having a garden over the river. Our proposal takes all the good bits of the Garden Bridge without the contentious bits'.