Pedestrian Walkway: Delivering A Safe, Movable Ferry Bridge On-Time With Nook Ball Screw Jacks

Isleburn Mackay & Macleod Ltd. designs and fabricates systems and components for large marine-based structures. Recently, the firm won a contract to design and manufacture a movable, covered, pedestrian walkway at the Aberdeen Ferry Terminal in Aberdeen, Scotland. Northlink Ferry Company operates a daily ferry, which transports passengers and automobiles back and forth between Aberdeen and the Shetland Islands, and needed an adjustable pedestrian bridge that could be raised and lowered to connect with ferries at different tidal levels and provide passengers with a safe, enclosed means for boarding and disembarking ships. According to Stuart Kydd, Project and Systems Manager at Isleburn Mackay & Macleod, the Aberdeen Ferry Terminal walkway project was particularly challenging because of the dramatic range in ocean tides that are possible at Aberdeen, the heavy loads involved, and more stringent safety requirements. "The tide differential at Aberdeen - the difference between high and low tide - can be as much as 20 feet," Kydd explains. "The walkway design not only had to address this wide tidal range but also had to support loads of up to 50 tons. Safety regulations governing the design of ferries and terminals have also increased dramatically in recent years. Our design had to be safe, strong, and highly movable."