Communication mast  – dismantle and re-erect – Durham

The scope of works included the dismantling and re-erecting of a grade 2 listed communication mast.
As part of an ongoing redevelopment programme within Durham, Durham Constabulary had relocated into a brand new, state-of-the-art headquarters. The old police HQ was going to be demolished and replaced with residential housing. All but one of the structures on the old site were demolished to make way for the new homes. The remaining structure was the iconic, 45 metre communication mast, designed and built-in 1965 by Ove Arup. As this mast had been a symbol of the Durham Constabulary HQ for more than 50 years, the decision was made to relocate the structure to the new police HQ.

O’Brien’s was tasked with relocating the mast which involved the dismantling, transportation and re-erection of the mast and the installation of new foundations. Due to its importance, the mast had been given a grade 2 listing, meaning no structural changes could be made and no damage could be sustained during the move.

Our engineering team decided the mast should be dismantled in four sections. The first would be the 30-metre centre spire, with the remaining three sections being the 15-metre legs. For the 30 meter spire section, a specialist lifting bracket was designed, manufactured and installed. This ensured that no damage was caused during the lifting operation. A 500 ton mobile crane was used to lift the spire section free from the legs in a vertical position. A 160 ton mobile crane was used to “top & tail” the spire section from a vertical position to a horizontal position. This was carefully planned to ensure the lifting accessories were attached at the correct locations so that structural integrity was not compromised during the rotation. The 30 metre section was then lifted on to a specialist abnormal load trailer ready for road transport off-site. To dismantle the remaining 3 legs O’Brien’s used three smaller 160-ton mobile cranes, each on one leg, so that all legs were supported when the keystone was removed. The leg sections were then lifted on to transport and moved to the new location.

The O’Brien’s team carried out all aspects of the lifting operations including:

• Initial site survey
• Calculations of load weights
• Design of dismantling sequence
• Design, Engineering and Manufacturing of specialist lifting brackets
• Ground loading calculations
• Provision of risk analysis
• Provision of detailed lift plan’s
• Planning, supervision and execution of lifting operations