Client: Westonbirt Arboretum, Forestry Commission
Architect: Glenn Howells Architects
Principal contractor: Speller Metcalfe
Structural engineer: BuroHappold Engineering
Steel fabricator: SH Structures Ltd
Tata Steel products: Celsius® 355 Structural Hollow Section
Steel bender: The Angle Ring Company Ltd
Year: 2016

The STIHL Treetop Walkway was constructed as part of The Westonbirt Project, a major five-year development programme at the National Arboretum at Westonbirt, Gloucestershire, which also included a new car park and Welcome Building along with restoration of a listed downland landscape.

Opened in the spring of 2016, the elevated walkway takes visitors through the treetop canopy and offers a bird’s eye view of the Westonbirt landscape and tree collection.

The challenge

Creation of the STIHL Treetop Walkway formed part of the final phase of the programme and was conceived to enhance year-round visitor interest for the arboretum and connect people more closely with trees.

The design contract was awarded to Glenn Howells Architects, who working closely with BuroHappold Engineering, designed the 300 metre-long walkway that winds through the trees and incorporates several features.

Aesthetics were obviously also a key requisite in enabling the structure to harmonise beautifully with its woodland environment.

The solution

Steel structural hollow section was selected for the main structure because it’s a robust, durable and compact material. Importantly, it could be bent to create the sinuous form, which rises to around 13 metres.

A significant amount of section bending was required to achieve the walkway’s curving form. Tata Steel’s Celsius® 355 Structural Hollow Section was utilised in the build. In addition to offering weight savings and proven performance, hot-finished Celsius® 355 delivered the high levels of formability required.

The walkway doubles in width at ‘pause locations’ and incorporates features – also constructed from structural hollow section – including a raised ‘crow’s nest’ viewing platform that wraps completely around a tall pine tree.