Thomas James Bridge Restoration

• Land and slope stabilisation around the bridge, including clearing and stabilising a 250-metre (approx.) landslip on the approach road
• Construction of a temporary traffic bypass, including slope stability, new culvert/causeway and other protective measures such as lighting and traffic management
• Deconstruction of existing convict-built sandstone retaining walls, including cataloguing, wrapping and storing each sandstone block
• Excavation to bedrock/foundation layer under archaeologist supervision
• Construction of concrete retaining wall, including ground anchors and piles
• Structural fill and sub-soil drainage
• Reconstruction of Thomas James Bridge, including reinstating the timber bridge deck to reflect the original appearance and historical engineering characteristics of the bridge, while still achieving a modern design load
• Reconstruction of the heritage structure, including the reinstatement of sandstone block wall with every block replaced into its original position
• Construction of a viewing platform using sandstone blocks
• Construction of new approach roads, including signage and crash barriers
• Demolition of temporary access road and restoration of the affected area
• Relocation of level 2 high voltage power lines
• Reinstallation of multiple services and utilities

Navigating the rural location and access challenges

With the project site located 45 minutes from the nearest town and from essential suppliers, this project required a high level of planning, procurement, and management to ensure that time-critical deliveries, including materials and equipment, were made efficiently.
With the site only being accessible via ferry, this presented additional challenges beyond navigating concrete curing times. The Delaney Civil team needed to keep the works progressing despite Transport Union work stoppages, ferry breakdowns, adverse weather events and tidal variations that affected the mobilisation of heavy plant and machinery.

Heritage listed bridge

To honour the heritage significance of the Thomas James Bridge, the Delaney Civil team worked closely with and under the guidance of archaeologists and heritage consultants throughout construction. Their expertise ensured that all restoration efforts complied with heritage requirements and preserved the bridge’s historical value while ensuring its functionality and ability to service the community in future adverse weather events.

The sandstone blocks, which were quarried and hand-cut on site in 1831, were once a functional part of the bridge’s structure. However, to ensure the bridge’s continued safety, reinforced concrete footings and retaining walls were introduced. The sandstone blocks, while no longer serving as load-bearing elements, were carefully reinstated as a non-structural façade. Each stone was carefully catalogued, photographed, and wrapped for protection before being reinstated in its original location, ensuring the authenticity of the structure was maintained, as well as the heritage look.

Design changes during construction

After due diligence reviews, the original timber bridge design was modified to a concrete structure with a timber facade. This change was crucial for ensuring long-term structural durability, while preserving the heritage look of the bridge. This approach also extended to steel traffic barriers which were specifically designed to resemble timber, maintaining the aesthetic integrity of the original design while meeting modern safety and engineering standards.

During excavation, large boulders were also uncovered that had been too large to move during the bridge’s original construction in 1831, so they were embedded into the bridge’s foundation. These boulders could not be removed due to heritage reasons, as it would have been impossible to return them to their current positions.
To mitigate this, Delaney Civil implemented geo-concrete solutions to ensure no load transfer to the boulders. The foundations of the bridge were extended beyond the uncovered boulders, and an alternate reinforced concrete retaining wall was constructed on the St Albans side to maintain structural integrity.

A solution for community access

The initial construction agreement was that residents would have access only twice daily throughout the period of construction. This restricted essential services like ambulances and waste disposal, leaving the community at risk.
However, when awarded the project, Delaney Civil presented an alternative solution and constructed a temporary bypass road, restoring 24-hour access and allowing essential services to resume throughout the construction. Larger vehicles such as water and waste trucks could finally reach the community and enhance quality of life during the construction works.