Gogar roundabout arches in Edinburgh

Complex arch design and structural detailing incorporating aerodynamic analysis, designing specialist foundations and overcoming logistical challenges

The challenge

Inertia Consulting Ltd was appointed by JCDecaux to create a complex and iconic design for the Edinburgh arches on the Gogar roundabout on the A8. We were required to merge architectural aesthetics with structural ingenuity, as well as incorporate giant video advertising screens into our designs.

Engineering Consultancy

The finished structures are 37m wide and 8.7m tall. The main structural members are constructed using curved circular hollow sections, to give the impression of a continuous arch.

Key challenges and solutions included:

• Designing and carrying out an aerodynamic testing case study, using an analytical wind tunnel simulator to ascertain the effect of wind turbulence from each arch on the other arches and surrounding existing structures.
• As the use of ‘spread’ foundations wasn’t possible due to lack of space and the risk of surcharging existing retaining walls the design opted for reinforced concrete piles.
• Designing the project to install the superstructure over a weekend and have it showing adverts on Monday rush hour. To do this we designed modules containing the large screens so that they could be assembled complete with all electronics and tested off-site before being installed as a plug and play structure.

The outcome

Our ability to design and draft civil and structural drawings in-house meant we could control the content and flow of information for the designs and drawings, and quickly implement any changes. In turn, this enabled us to offer a fast-track delivery to our client.

Concerns around how the new and existing structures would interact with each other were successfully addressed by the innovative engineering solution we proposed.

Our standard practice of involving the fabricator in the design process paid off, as we believe the best solutions are achieved by working holistically.



The process followed by the Inertia Consulting team exceeded the expectations of all the project’s stakeholders.

The project was successfully installed within the weekend closure, and much to JCDecaux’s delight, the screens were displaying adverts by Monday rush hour.

The project
  • JCDecaux – Client
  • 8Point8 Construction – Principal Contractor
  • Inertia Consulting Ltd – Principal Designer
  • Briton Fabricators Ltd – Steelwork Fabricator