News: Thomas Heatherwick has released images of a proposal for a garden to span the River Thames on a new pedestrian bridge (+ slideshow).

The design was developed by Heatherwick Studio after Transport for London awarded it a tender to develop ideas for improving pedestrian links across the river.

Images show two fluted piers supporting a walkway planted with trees, grasses and flowers, offering views of the surrounding city.

"With its rich heritage of allotments, gardens, heathland, parks and squares, London is one of the greenest cities in the world," says Thomas Heatherwick. "In this context we are excited to have been selected by TFL to explore the opportunity of a pedestrian river crossing. The idea is simple; to connect north and south London with a garden."

The structure is proposed for a site between the existing Blackfriars and Waterloo bridges, and will cost £60 million, which Heatherwick will be required to raise from private investors.

Isabel Dedring, London's deputy mayor for transport told the Evening Standard that "The mayor has been keen to find an iconic piece of green infrastructure that can symbolise London as a high quality of life place to live," adding "but if private sector funding isn’t forthcoming then the project isn’t going to be able to go ahead."

This would be the first new bridge built on the river since the Millennium Bridge by Foster + Partners, which originally opened in 2000 but was closed due to safety concerns and reopened in 2002.

Heatherwick Studio says it has been working on the idea with actor and campaigner Joanna Lumley, who adds: "It's quite strange to talk of something that doesn't exist yet, but the Garden Bridge is already vivid in the plans and the imagination. This garden will be sensational in every way: a place with no noise or traffic where the only sounds will be birdsong and bees buzzing and the wind in the trees, and below the steady rush of water."

"It will be the slowest way to cross the river, as people will dawdle and lean on parapets and stare at the great cityscapes all around; but it will also be a safe and swift way for the weary commuter to make his way back over the Thames," says Lumley.

"There will be grasses, trees, wild flowers, and plants, unique to London's natural riverside habitat. And there will be blossom in the spring and even a Christmas tree in mid-winter. I believe it will bring to Londoners and visitors alike peace and beauty and magic."

Thomas Heatherwick designed the cauldron for the London 2012 Olympics and told us that its lighting was conceived as a religious ceremony.

Heatherwick's design for a new bus took to the streets of London last year, and he has also recently designed a distillery and visitor centre for gin brand Bombay Sapphire - see all design by Thomas Heatherwick.

Yesterday the winners were announced in a competition to develop a new green space linking sites on London's Southbank, which aims to rival the popular High Line park in New York - see all stories about parks and gardens.

We've also recently reported on a series of bridges in the Netherlands that were copied from the fictions structures depicted on banknotes - see all stories about bridge design.

Visualisations are by Heatherwick Studio.