The Treetop Trail at the Minnesota Zoo is currently the longest elevated pedestrian loop in the world, spanning 1.25 miles with a peak height of 32 feet above ground. However, before its completion in 2023, the monorail track it was built on had been dormant for nearly a decade.

The first iteration of the trail had operated as a monorail beginning in 1979 until high maintenance costs and low availability of parts led to its decommissioning just over a decade ago. With animal well-being, guest experience, and ecological preservation at the forefront, the zoo began a search for a construction partner with specialized knowledge to replace this fan-favorite attraction.

Not many contractors had the experience required to navigate nocturnal sleep schedules, among other specific animal requirements and construct a must-see attraction while remaining invisible to guests (and animals) – yet PCL’s portfolio of successful zoo and entertainment projects is extensive. 

PCL was selected to build the elevated boardwalk project after demonstrating how the team would leverage the latest techniques in prefabricated construction to build the trail from the top down, thereby minimizing disruption to the guests and the animals.

To achieve this approach, 20-foot, prefabricated sections of the boardwalk were built off-site and then rolled into place on the track via a trolly. Two trolleys were integral to the project. The first trolly, approximately 45 years old, underwent maintenance tests by PCL, leading to the replacement of several parts for safety and functionality. The second trolley was a custom design crafted collaboratively between PCL and the manufacturer. Using these two trolleys as scaffolding allowed the project team to work above the zoo without disturbing the animals or guests, ensuring the zoo could remain operational during construction. The build consisted of 1,000 tons of structural steel, 2.8 miles of steel guard rail, 131,750 linear feet of decking boards (25 miles of boards if laid end-to-end), and just under 80,000 deck board fasteners that were installed by PCL.

By deploying detailed maps and coordination plans, the team ensured the zoo didn’t lose any days of operation during construction, preserving the guest experience. Throughout the project, the team scheduled meetings with the zoo’s animal care and health team to ensure they were not disrupting the animals, with special attention paid to the sleep cycles and animal mating seasons. During the meetings, the project team collaborated with the zookeepers and zoo veterinarians on how to sequence work around the various animals to limit exposure to unfamiliar scents and noises.

Additionally, working closely with design teams, the team customized every element, from the decking materials to the fastening mechanisms to the zoo’s unique needs. Frequently soliciting and incorporating the client’s feedback, PCL ensured high-quality results for the project.

PCL’s approach to the Treetop Trail is a testament to the company’s expertise, adaptability, and commitment to excellence. By merging innovative solutions with a deep understanding of the zoo's requirements, the team not only executed a complex project seamlessly but also enhanced the overall zoo experience.

PCL has constructed numerous projects for the Minnesota Zoo over the years, including upgrades to the aviary building, construction of the Dino Trail animatronic attraction, upgrades to the upper and lower plaza, and the Crossroads Park Play Area.

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