News

Tallest Flagpole in the World

Oct 30, 2014

The Jeddah Flagpole has been officially recognised by The Guinness Book of World Records as the world’s tallest, at 171m high. It is located on the Tariq Ben Zayed Roundabout in central Jeddah, Kingdom of Saudi Arabia and carries a flag approximately 30x60m weighing up to 1 tonne.

Byrne Looby Partners have been involved on this landmark project from start to finish. Employed by the design and build contractor, Al Babtain LeBLANC Technologies FZCO, Byrne Looby planned and supervised the initial site investigation, designed the piling and foundations and provided site supervision throughout the construction.

The Byrne Looby project team consisted of John Byrne leading the geotechnical input, Richard Thiemann heading the structural element, Sam Peet undertaking all the computer modelling while Ian Pearcy and Aidan Commerford were responsible for the drafting. Byrne Looby had three people on site throughout the different stages of the project.  

The ground comprised coralline limestone over sandstones, siltstones and mudstones and it required 16 piles 25m long and 1200mm in diameter to support the foundation block.

      
Pictured: Byrne Looby name going into the structure.                                                            Pictured: Top of Flagpole                          Pictured: Guinness World Record Certificate

As well as resisting the high moments and shear from wind loads on the flagpole the foundations needed to provide sufficient stiffness to avoid build-up of resonant vibrations. The foundation comprised an octagonal reinforced concrete base 16m across and 2m deep with a 2.5m high plinth on top. To resist the very high oscillating loads under the flagpole base a C45/55 concrete was specified for the plinth whilst the base was reduced to C32/40. Despite the high concrete strengths the base was tanked to provide adequate durability against the aggressive soils.

The high concrete strengths meant high potential temperature during curing of the concrete. Careful design of the mix was required together with batching with iced water and cooling of the aggregate. To ensure the precautions were adequate a 2x2m test cube was poured and temperatures monitored. The foundation was poured in two sections, the base and the plinth.

The flagpole was a tubular steel structure tapering from 5m diameter at its base to 2m at the top. It enclosed an access stair and the flag raising mechanism. The flagpole was erected in segments and bolted to the foundation with 168 pretensioned bolts fixed to a double anchor ring within the base.

Byrne Looby staff were resident on site throughout the works to confirm that works were constructed in accordance with specifications and to provide full records of the works carried out.