In our experience as a small office working on large projects with multidisciplinary teams, our role can often be described as creating the vital link between the project (building, group of buildings, master plan) and the site. Typically we mine the cultural and physical histories of a site to develop a conceptual narrative that will guide our designs and result in the creation of a unique, contextual sense of place.
Commonly understood metaphors attributed to landscape often have to do with grounding, rooting, and connections to the land. However, more often than not, we find that our landscapes are not constructed on or in the ground, but rather on a concrete slab. This is typically the roof of a significant structure: a parking garage, mechanical space, auditorium or gallery space. A myriad of technical challenges and constraints emerge in such situations, but most fundamental to the overall design is the conceptual question of how to deal with this constructed ground.

Two recent projects, The Lurie Garden in Chicago and North End Parks in Boston are instructive in how the technical challenges (i.e. bearing weight of the slab, minimum soil depths and drainage issues) are integrated with the conceptual framework that guided the design. Both of these projects cover the structures on which they sit. They are conceived of and built in the spirit of healing and re-stitching previously eroded urban fabric. The basic approach re-enforces much larger urban planning initiatives in both cities, but each project developed into a unique, site specific response that resulted from the integration of technical constraints with conceptual narratives.

The Lurie Garden is constructed on top of a parking garage, which itself is built over a still-functioning rail yard, an infrastructural chasm that had up to this point separated Grant Park and the Lake Michigan waterfront from downtown Chicago. The underground garage presented a programmatic challenge; the park needs to accommodate 10,000+ people as they head across the site towards the garage entries on the southern end of the garden. Additionally, there were structural constraints relative to the competing requirements of the soil depth required for plants and the load-bearing capacity of the surface of the slab.

Conceptually, the experience of the park was designed around the history of Chicago and its evolution as a city. Knowing that soil would have to be built up to get any planting depth, the ground was manipulated to create two different topographic experiences: those where visitors are in the landscape, achieved by retaining walls, and those where they are on the landscape, achieved through gentle grading. The different relationships between the ground and the body are equated with different points in Chicago’s evolution and articulated as such in the plantings and detailing. Where they are fully exposed, retaining walls are used to distinguish the two zones, to delineate an internal path through the garden, and to provide some of the metaphorical connections to the history of the site.

North End Parks in Boston is being built on top of the newly-buried Interstate 93, a tunnel structure that replaced the formerly elevated highway. Until it was demolished, this highway acted as a barrier separating the North End neighborhood of Boston from the central downtown core. Because the two neighborhoods developed in drastically different ways, the park design does not try to join them but rather creates a threshold between them through a series of low walls and landforms composed perpendicular to the path of travel. The grain of the walls and landforms follows and expresses the direction and line of the tunnel below. Those lines create a continuity across the two blocks that acts as an essential compositional driver. Maintaining that continuity proved challenging because differences between the existing slope of the surrounding context and the flat top of the new tunnels created critical pinch points that in turn drove many of the grading decisions.

We are currently working on a series of projects which present different on-structure challenges. As ‘green design’ flourishes all around us, elevated rooftops and terraces become our new ground on a very large scale. With buried structures, a connection to the ground is at least possible at the edges. With elevated structures, guardrails and parapets become the horizon line and our connections are visual. These projects force us to carefully consider and reprogram the functions that the ground conventionally performs. The constructed ground has driven a deeper inquiry into the question of what ground really is, how it functions and where it should be. Formulating appropriate conceptual frameworks for these landscapes is an on-going endeavor and is representative of some of the challenges we deal with daily in the office.

Rodrigo Abela holds a M.Arch and MLA from the University of Virginia, and has been working with Gustafson Guthrie Nichol since 2000. He currently runs a satellite office in the Washington, D.C. area.

Ian Horton holds a MLA from the University of Virginia.