The central message of “Tree Adventure” at the Morris Arboretum of the University of Pennsylvania in Philadelphia is: “We need trees and the urban forest needs us.” The centerpiece, “Out on a Limb,” is a 450-foot- (137-m-) long walkway to the treetops, and “Squirrel Scramble” is an open net climb suspended50 feet (15 m) above the forest floor.
Completed in July 2009, Philadelphia-based Metcalfe Architecture
& Design worked closely with the structural engineer, CVM Engineering, Oaks, Pa., to design a structure that did not hang on the trees for risk of killing the trees and/or having a falling tree destroy the structure, but instead consists of tall towers and ramps that weave the way through the forest. If a tree hits and damages one part of Out on a Limb, the other parts will continue to stand alone.
Metcalfe created an interpretive plan for all visitor experiences at the Morris Arboretum, including the design and planning of Tree Adventure, an exhibit occurring in nodes throughout the grounds. The design incorporates sustainable green strategies for construction, site impact and choice of materials.
Made of recyclable metal and wood, this lightweight structure consists of steel and 6-inch (152-mm) diameter “micropile” foundations that are delicately located amongst the trees. The exhibit-structure and interpretive components-was built and assembled off-site in a manufacturing plant, rather than on-site, lessening the impact on the environment and natural wooded site.
The design is broken into 30-foot (9-m) lengths of walkway that terminate in a balcony with an exhibit or observation area that surveys a different part of the forest below, encouraging a slower trip for users and queues visitors to stop and look at their surroundings.
DDM Steel Services, Vineland, N.J., supplied the structural steel; American Galvanizing Co.,Folsom, N.J., did the hot-dip galvanizing; Ametco Manufacturing Corp., Willoughby, Ohio, supplied the steel railing panels; Ohio Gratings Inc., Canton,Ohio, supplied the hot-dip galvanized steel grating International Cordage, Phoenix, supplied the stainless-steel bronze finish Invisinet; and Valmont Structures, Plymouth, Ind., supplied the galvanized steel monopoles.
CVM Construction, Oaks, was the construction manager; Hunt Engineering Co., Malvern, Pa., was the civil engineer; Grenald Waldron Associates, Narberth, Pa., was the lighting designer; and Sparks Exhibits and Environments, Philadelphia, was the exhibit designer. The nonprofit Forever Young Treehouses Inc., Warren, Vt., promotes the construction of universally accessible treehouses across the country, played a large role in the project.
Ametco Manufacturing Corp., www.ametco.com
DDM Steel Services, (856) 794-9400
International Cordage, www.international-cordage.net
Ohio Gratings Inc., www.ohiogratings.com
Valmont Structures, www.valmont.com
