Landscape architects James Corner Field Operations have designed a new park for downtown Miami to be constructed beneath an elevated rail line.

Working with non-profit group Friends of The Underline, James Corner Field Operations have developed the vision and masterplan for a 10-mile-long (16km) park and urban trail. The scheme makes use of an under-used area of land below a portion of Miami's MetroRail – a rapid-transit system that opened in 1984 and runs through the city's urban core.

Following the route of an existing bike trail, The Underline corridor, running below Miami-Dade’s Metrorail from the Miami River to Dadeland South Station, will create a linear park that will enhance connectivity, mobility and biking safety for hundreds of thousands of Miami-Dade residents and visitors. The company’s design team, including Pentagram and several other consultants, is also providing more detailed designs for two demonstration projects that will include the Brickell area and an additional site yet to be determined.

Friends of The Underline was founded by Meg Daly, a Miami-based marketing specialist, who came up with the idea for the park when, unable to drive having broken both arms, she started taking the MetroRail, walking beneath the tracks. Shaded from the July sun by the tracks and seeing that she was the only person there, Daly realised the potential of the area for a linear park space.

Friends of The Underline presented its initial vision to city officials in July and is now working to win planning approval and raise money for the project. Partners include the Miami-Dade County Parks, Recreation and Open Spaces department, together with the county's transit department. The University of Miami’s School of Architecture is also supporting the project by providing student and faculty resources.

“The Underline will be the spine of this future network of 250 miles (402km) of trails,” said the Friends of The Underline. The goal of the project is to transform the land into “an iconic linear park, world-class urban trail and living art destination,” they added.

The park plans feature extensive spaces for leisure, art and recreation, with more than 100 acres of open space with restored natural habitats, along with an area for pop-up structures that could serve as small business incubators. A bike tune-up station is also included in the plans.