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New Zealand Lifting Bridge

Eadon Consulting often receives enquiries from around the world relating to large moving structures they require assistance with. Back in December 2009 we received an initial contact from structural engineering consultancy Novare Design (formally Peters and Cheung) in New Zealand. They had heard of a potential project coming up and wanted to secure our services to assist them and their client McConnell Dowell with a moving bridge. Over the following months we conversed via email, then teleconference, then video conference until in February 2011 I ended up flying out to New Zealand to assist their team with the client presentation. The preparation for the presentation and the presentation itself did not last long so it was a long way to go for such a short meeting but by attending it showed the client the design team’s commitment to the project which scored very favourably with the client when the tender scores were assessed. For further project details click here.

By Michael Thorogood

Once the project was awarded several further trips to New Zealand occurred, the first being to sit down with the rest of the design team, including UK based Knight Architects to come up with a concept and present this concept to the client and key stakeholders.

The concept arrived at was a rolling bascule bridge. The majority of rolling bascule bridges are pulled back by a rack and pinion arrangement mounted at an elevated level using a large and bulky frame. The architectural vision was for something that was minimal and visually simple. As part of the initial design stage we investigated several different methods of operating the bridge. The simplest and most proven solution was to lift the deck using a pair of hydraulic cylinders. Whilst hydraulic cylinders are fairly common on lifting bridges there is only one known instance of them being used on rolling bascules.

One of the greatest challenges of the project was the balancing of the of the deck to minimise loading on the operating equipment. In order to do this various key constraints had to be considered simultaneously to arrive at the optimal solution. These key constraints included the radius of the rolling track, the height and inclination of the mast that balanced the bridge and the length and location of the hydraulic cylinders. Due to the many inter-related aspects including an impact on the architectural aspects of the bridge close collaboration was required with the architect.

The initial concept was developed further to the point of issuing drawings and documentation for tender.  Another visit to New Zealand was required to assess the potential suppliers of the equipment and to develop the design further with these suppliers and the rest of the design team.

Once the design had been finalised we produced a set of detailed manufacturing drawings for the mechanical equipment accompanied by detailed specification documents for the electrical and control equipment. A final, and very satisfying, visit occurred close to completion of the project when I went to site to witness the commissioning of the equipment.

The project has been a massive success for the local community. They have embraced the project and taken it into their local identity. The project has also won many awards and been featured in TV adverts and news articles internationally, including the cover of the bridge industry magazine, Bridge Design and Engineering.

This type of project is very enjoyable because it gives us the opportunity to show case our capability internationally. This has also led to us receiving other interesting enquiries.


For more information about any of our projects or services or to discuss your requirements, please telephone 0114 399 0400 or contact us.

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