The Brigham Street Bridge forms part of the Wyndham quarter wharf, the bridge is contained within the Auckland City Councils Roading network and is an asset under the ARMA –West maintenance umbrella.
The bridge was originally constructed using a cast insitu concrete system for the beams, girder, braces and deck. The deck has approximately 40 x 3.5m x 300 x 400mm beams, 2 x outside girders and one central girder.
Over the years the aggressive coastal conditions have caused the concrete to spall, breakaway from the reinforcing, leaving the reinforcing exposed to the elements. This has caused the bridge structure to loose its structural integrity and become a concern to the authorities.
The design of the repair works was undertaken by MWH who designed a system of constructing cast insitu shell beams to surround the existing degenerated beams. New Reinforcing was to be welded to existing stubs but due to the presence of volatile gases a drill and epoxy method has been used. The beams are then constructed using formwork and Sika Micro Concrete.
The nature of the wharf presents some very difficult aspects to over come:
- Confined space
- Maintain a safe breathing atmosphere due to Limited oxygen supply
- Presence of hydrocarbons
- Overhead construction traffic
- Limited access
To overcome these factors a high level of Health and Safety planning is required to provide a safe working environment, this includes:
- Forced air ventilation
- Intrinsically safe tools, lighting and radio equipment.
- Dedicated spotters and monitoring by Health and Safety officers
- Strict working Protocols
- Life preserving safety apparatus and escape plans and routes
- Fully trained staff in confined space and rescue methods
- Methodology changes to suit the environment