Mike Stewart, project director, Babcock Networks
When planning to replace TV antennas for telecoms company Arqiva at two of its sites in Scotland and Somerset, we hadn’t considered using a helicopter to lift structures until we realised that the main antenna systems couldn’t be removed and replaced using a traditional derrick crane.
The tops of TV masts are around 1,000 feet above ground level, and special lifting techniques are needed to install them. A derrick is usually attached to the structure and lifting is carried out via a lifting bond that runs from a winch at ground level and through a block on the top of the derrick.
With these two jobs, one of the masts in Scotland had insufficient space available on the mast column to install the derrick, while the Somerset mast had a tubular column which also meant we couldn’t install a crane.
Rather than re-engineering the existing structures to accommodate a bespoke derrick we opted to use a helicopter. It was to become the first heavy-lift operation of its type in the UK. We subcontracted the work to Helirig, which provided a complete service including the helicopter, fuel and Civil Aviation Authority clearance.
Helirig removed each of the main, four-tonne antennas, and two-tonne interface units from the tops of masts and replaced them with larger and heavier units capable of transmitting digital TV signals.
Lifts were completed in a fraction of the time it would have taken using a derrick – work in Scotland was completed in four days, while the Somerset job took just hours. Remarkable considering that the site teams met the helicopter crew only a few hours before each lift.