Fernbank Museum of Natural History, ‘Wildwoods’ – Montgomery Highline Trace
Fernbank Museum of Natural History is the preeminent Natural Science Museum in the Southeast and one of Atlanta’s most popular cultural destinations. The Museum’s campus includes the 65-acre Fernbank Forest, one of the largest old-growth forests in any U.S. metropolitan area.
The Montgomery Highline Trace tree canopy walkway and tree pods are a part of Fernbank’s larger ‘WildWoods’ project. The overall project goal was to make powerful connections between the Museum and Fernbank Forest; physically and programmatically. Wildwoods provides outdoor programming on ten acres behind the Museum, including immersive exhibitions and experiences integrated with the site’s topography, hydrological systems, tree canopy, restored Piedmont mesic forest and biodiverse wetlands and riparian corridor, offering critical ecological support to Fernbank Forest.
The Montgomery Highline Trace tree canopy walkway provides a universally accessible path with biomimetic integrated learning spaces and experiential exhibits. The walkway navigates the 15’ change in elevation at the Museum’s outdoor terrace to the adjacent forest floor and connects visitors to a mile of elevated boardwalks and bridges ultimately leading to a trail that connects visitors to Fernbank Forest. Visitors are drawn directly in to the trees from the Museum terrace level and experience new perspectives along the tree canopy walkway, through the majestic tree canopy and to biodiverse restored lowland habitats thirty-five feet below.
The design for the elevated walkway and pods was inspired by the forest itself. The forms, materials, colors, patterns and even the construction method were all rooted in a biomimetic idea to blend in with the forest, while also seeking moments of surprise and inspiration. The walkway literally flows from the museum terrace in a curvilinear path that negotiates between towering trees, widens at times to provide space for visitors to pause, and establishes more dramatic moments when the forest’s grandeur is revealed. At these locations two viewing platforms (“pods”) are sited to provide space to learn, be
inspired and reflect on the beauty all around– into the forest, up into the tree canopy, and down into the riparian zone of Peavine Creek.
One pod is inspired by the Tulip Poplar flower, the most prevalent tree in the Forest, and one is inspired by the ferns for which the museum is named. Each pod was designed to take advantage of a specific location in the forest and, as a result, each has a distinct character. The “Petal” pod is larger and more open, and it emphasizes views along the length of the creek at its base. It is 26’ in height and the floor of the pod is 35’ above the creek corridor. The “Fern” pod is more enclosed as it is nestled in a cluster of four trees and focuses views upwards into their canopy.
Design Challenge1. Building a significant structure while minimizing impact on a sensitive ecosystem.
The existing forest site has mature growth trees and extremely steep slopes. This required the design team to conceive of a structure that could be built with minimal disruption. The steep slopes and tree root zones limited the amount and type of equipment that could be used to erect the walkway and pods. Therefore, both the pods and the walkway are comprised of relatively small parts that were transported into the forest using small equipment or carried in by hand and then erected piece by piece. For example, the cypress louvers on the pods are 1x material that was cut to size and erected using the elevated walkway as a working platform. The decking material—Cumaru, a sustainable hardwood known for its inherent durability in exterior applications—was installed starting at the top of the walkway and working down the ramp as each section of steel was erected. The steel structure itself uses relatively small members spaced as widely as possible to minimize impact on the forest floor. The columns actually sit on baseplates that float above grade and then are tied into the ground using helical anchors that minimize disturbance of the terrain.
2. Documenting and constructing complex geometrical forms in a natural environment.
The site for this project was absent of the typical reference points that design teams normally rely upon, such as set finished grade, street elevations or adjacent buildings. The curved, sloped steel structure and hundreds of individual louver and decking dimensions and associated attachment points made it impossible to document the project in a conventional manner. The design team worked closely with the Structural Engineers and the Contractor to develop a digital-model based delivery method that made extensive use of computational modeling techniques, part scheduling and shop-drawing level documentation techniques in order to produce the project.
Physical ContextThe entire project intervenes as minimally as possible in the sensitive forest ecosystem. A kit of parts approach minimized the amount and size of equipment used to install the project, and the steel structure carries the loads as efficiently as possible. As a result, the impact on the forest floor is much less than might otherwise be expected and the overall structure itself is as slender and unobtrusive as possible in the forest context. The trajectory of the walkway was determined in part by the length needed to transition accessibly from the terrace to the forest floor, but more importantly, it was designed to thread between existing trees and their associated critical root zones (no trees were removed to accommodate the walkway). The palette of materials used for the project is sensitive to the natural environment.
The materials were selected to prioritize longevity in a natural, weathering context. Thus, Ipe and Cumaru wood were selected for the guardrail and the walkway decking. The pod louvers are made of Red Cypress, which also has good natural weathering characteristics and performs well in wet, humid environments. Cypress was also selected for the louvers because it could be easily cut and adjusted in the field as the louvers were installed. The steel members were painted a grayish-brown color along with the 12” diameter of the columns helps them to blend in with the existing tree trunks. Finally, a stainless steel mesh railing system makes the guardrail as transparent as possible and minimizes barriers between visitors and the forest.