US studio Nelson Byrd Woltz Landscape Architects has covered a six-lane highway with a sprawling land bridge and park in Houston that symbolises "the triumph of green over grey".

Called the Kinder Land Bridge and Cyvia and Melvyn Wolff Prairie, the project is part of a ten-year master plan launched in 2015 by Nelson Byrd Woltz Landscape Architects to overhaul a 1,464-acre wilderness area just outside of downtown Houston.

The Land Bridge and Prairie is located at the centre of Memorial Park and links two sides of a greenspace that was previously disconnected due to the installation of a six-lane highway built in 1955.

To mend the divide, Nelson Byrd Woltz built two tunnels – measuring 400 and 560 feet long (121 and 171 metres) – over the drive that pass through the sprawling land bridge.

The resulting structure was then covered in over half a million cubic yards of soil to create an earthen base for grasses and pathways.

"The Land Bridge itself creates two dynamic connections over Memorial Drive that reunite the north and south sides of Memorial Park while expanding the existing network of trail systems and providing increased connectivity throughout," said the studio.

The bridge is split into two sections, or mounds of earth, with a portion of the highway exposed at the centre.

The construction of the bridge required collaboration across a variety of disciplines, including engineers, prairie experts and fluvial geomorphologists.

Stormwater management techniques, like a constructed stream bed, were installed in order to mitigate flooding and improve water quality treatment.

"The project is not just a physical link like most other land bridges; it's a nexus where complex and multifaceted systems – both human and natural – have been holistically conceived as part of a greater vision," said the studio.

Gentle sloping curving pathways were placed along the length of the area, with a central ellipses-shaped path rising up and over each section.

"Nelson Byrd Woltz wanted everyone to be able to use the same paths up and down the land bridge so they were designed in such a way that their grade is gentle enough (and this requires curves) so that all people of all abilities can use them," said the team.

Beside the pathways, the surrounding 45-acre landscape was left largely unpopulated by infrastructure.

The gently sloping hills were planted with grasses, shrubs and trees of North America's coastal prairie environment, an endangered habitat with less than 1 per cent of its original 8 million acres (3,240,000 hectares) remaining throughout the U.S.

The landscape was designed to withstand storms and manage stormwater, as well as to provide a habitat for animals and cleaner air for humans.

"This new parkland will symbolize the triumph of green over grey," said the studio. "Healing the divide created by the construction of Memorial Drive."

The Land Bridge and Prarie was opened earlier this year.

Other parts of the park have recently undergone redevelopment, such as the Eastern Glades section, which contains 100 acres of previously inaccessible parkland outfitted with wooden boardwalks, pavilions and picnic tables.

A memorial concept to honour World War I soldiers who trained on the site is planned for completion at the end of the ten-year master plan in 2028.

Elsewhere in Houston, O'Neill McVoy studio designed a house as a "mini-manifesto against McMansions" and a large photovoltaic artwork is planned as part of the city's expansion of the Bayou Greenways.

The photography is by Nick Hubbard.