Bridge demolition over water? This is how we do it

A little known fact among industry outsiders is that demolition can involve some very intricate work.

To be completed safely and without incident, detailed planning, together with extreme caution is key.

Bridge removal over water adds another layer of complexity to a demolition project. Not only must all the usual considerations be factored into the methodology, often there are project specific concerns to be accounted for.

That’s exactly how it was for DEMEX last year on the Haughton River Bridge removal project.

Undertaken at Giru, a small regional town in Queensland located on the Bruce Highway, approximately 54 kilometres south east of Townsville, the Haughton River Floodplain Project was part of the Queensland State Government’s infrastructure upgrade of the Bruce Highway.

We were engaged as a subcontractor for demolition works by The Infrastructure Group, a joint venture between Beilby, BMD Constructions, JF Hull Holdings and Albem Operations.

Project works included demolition of a vehicle bridge over the Haughton River, Horseshoe Lagoon and Pink Lilly, in addition to two asbestos-containing houses and shacks.

Marine bridge demolition: Project highlights

Just about every project has its highlights and this was no exception. Among the project highlights were:

• Cost and time savings, which were achieved through use of an excavator and catchment barges
• Engagement of an Indigenous business for abutment removal of Pink Lily Bridge
• Project was delivered on time
• Zero environmental or safety incidents
• Tracking our performance in line with National Greenhouse and Energy Reporting (NGERS).

Every project brings its challenges, and the Haughton River Bridge demolition was no exception.

Working over a river course and in proximity to a main highway presented a unique working environment for our team. Additionally, the project’s timing, which occurred in the lead up to the wet season, was also a challenge, as was the movement of heavy vehicle traffic and equipment required for the sugar cane harvest season.

Bridge removal over water requires careful planning

It’s a given that planning is key for any project, so delivering a project regionally some 1,400 kilometres from DEMEX headquarters meant there was no margin for error. Our clients take us to interesting and often distant locations, a factor which adds to the challenge.

Before demolition commenced, silt and sediment controls were placed in and out of the water to prevent any disturbance to the marine environment.

In terms of methodology, the team used excavators fitted with rockbreakers; one each positioned on adjacent spans. Excavators hammered the concrete bridge deck onto a barge fitted with environmental catchment controls. Once the catchment barge had reached capacity, it was pushed to the riverbank from a specially made platform and unloaded by an excavator onto transport for recycling. This included the reinforcing that was removed from the concrete deck.

Bridge girders were oxy cut from an elevated work platform (EWP) positioned on a barge and lifted out using a crane positioned on an adjacent span until all bridge spans were completed. The crane was used to place girders onto transport for recycling.

Abutments were removed from land, while headstocks and piers were pulverised with a 30 tonne excavator on a barge into a catch deck at riverbed level.

Macalloy (transverse) bars were saw cut and bridge decks removed by grabs on Horseshoe Lagoon Bridge and Pink Lily Bridge. Headstocks and piers were pulverised from the next span to be removed, while bonded and friable asbestos was removed. Demolition of two houses brought the project to an end.

Although the Haughton River Bridge demolition was neither the largest nor most complex project, the outstanding performance of the team who delivered an incident-free project is a credit to their careful planning and good work. The DEMEX team received positive feedback from both the Department of Transport and BMD Constructions for the efficient and safe delivery of the project.

DEMEX is a specialist commercial demolition contractor for bridge demolition projects Australia-wide, including in Queensland, New South Wales, the Northern Territory, Western Australia, Victoria and Tasmania. From pedestrian bridges to major infrastructure projects, we understand the need for tailored solutions that adhere to sound demolition and safety principles. Through our experience as a bridge project contractor working in often challenging environments, we have assembled a strong team, from onsite operators to site supervisors and project managers. For information on bridge removal in your state or territory, download our capability statement or contact us directly on info@demex.com.au.