Civil Engineering March 2021 | Vol 29 No 2

Civil Engineering March 2021 49 WINNER IN THE SAFAL STEEL INNOVATION AND SUSTAINABILITY CATEGORY Whale Trail Staircase The De Hoop Whale Trail is a world- famous long-distance hiking trail in the De Hoop Nature Reserve. The hiking path is subject to sea air, mist and wind-borne salt spray, and the original timber and wire rope ladders on the mountainside have long since decayed. Cable or chain ladders were considered too risky, and a new stairway was approved. The brief The owner, CapeNature, stipulated that the stairway had to be aesthetically unobtrusive, sympathetic with the area, modular and lightweight, fireproof, and make minimal use of cement works. Wherever possible, the staircase had to follow the mountainside to blend in and it had to allow for perennial river flow in the stream bed. Maximum off-site manufacture was required. In addition, the remoteness of the site makes regular maintenance impractical. Road access to the site is only possible using a small four-wheel drive vehicle, with a rough climb from the unloading point to the installation site. All compo- nents had to be portable over rough ter- rain without endangering the installation contractor’s staff, and site welding had to be eliminated or minimised. Innovation With no information on the site available, ParaMatic used a 3D scanner to capture the site and modelled and detailed the new stairway in Tekla Structures. Without the scan of the site, the team would have had to rely on tape measures and photographs, normally problematic on a complex site. Absolutely no measure- ments were taken on site and the modeller was totally reliant on the output of the scanner. The scanner also allowed the team to plan around vegetation and decide when vegetation could be easily removed for later regrowth, taking deci- sions upfront which would have been referred to the field engineer during the construction. Structural framing A structural duplex hot dip galvanised solution was considered the most func- tional and economic solution. Standard hot rolled sections were used for the stair stringers and platforms and all elements were limited in mass to ensure they could be hand carried to site for bolted assembly. The final stair tread concept was a carcass of a thin plate with bolted-on machined timber stair inserts, selected for their anti-slip properties. Treads are replaceable, using counter sunk bolts. Using prefabricated frames changed the nature of the project, eliminating the need for boilermakers and welders to be given safe working platforms and con- verted the project into a simple erection sequence carried out by competent steel erectors.  KEY PLAYERS Nominator ParaMatic Client/Developer CapeNature