The business case phase is important because it confirms the project need, assesses how an upgrade could be designed and constructed, and develops cost estimates to support funding requests.

Geotechnical investigations have assessed sub-surface conditions in the area where a new bridge could be built to inform foundation design. A detailed assessment found the existing bridge can continue to be used for traffic with continuation of its maintenance program.

Peak period travel delays were found to be primarily experienced at the Benabrow Avenue and Sylvan Beach Esplanade intersections rather than on the bridge. However, the narrow bridge with 1 lane in each direction (opposing traffic flow) contributes to safety issues and travel delays when vehicles cannot pass during incidents such as crashes or breakdowns.

Reported incidents have an average duration of 2 hours. Unreported incidents also result in delays. While crashes are not common, they generally require medical treatment.

The population and traffic volume have grown significantly since the existing bridge was built in 1963. While the area continues to be popular with visitors, Bribie Island’s population and traffic volume are expected to experience moderate growth in the future.

The need for reliable access, improved safety and providing equitable access for pedestrians, bike riders and mobility devices are the greatest drivers for a new bridge rather than the condition of the existing bridge, peak period congestion or traffic volume growth.

The concept design confirms the new bridge’s northern location, next to the existing bridge, is the most viable location to limit environmental impacts, connect communities, and maximise use of existing state-owned properties.

Thank you to everyone who participated in consultation held in early 2023. TMR received more than 3600 responses. The consultation report is available in the document library on this page.

Consultation found that improved access, safety, and congestion were extremely important to the community as well as emergency service access. Respondents also highlighted the importance of reliable access to family, work, education, recreation, and community services with personal and commercial impacts noted. The narrow bike and pedestrian path was a key concern.

While preferences varied on the number of lanes, feedback generally supported a new bridge with the ability to move traffic between lanes during an incident, and active transport improvements for pedestrians, bike riders and mobility devices. Improvements to roads either side of the bridge were also requested.

Feedback expressed a desire to keep the existing bridge, noting its iconic status and heritage character. There were some requests for fishing, markets, cafes and landscaping on the existing bridge.

The community requested a sustainable, value-for-money solution that considers the environment and future transport needs.

Supporters for a new bridge referred to benefits such as improved traffic flow, connection, health, safety, lifestyle, tourism and economic growth.

Opponents to a new bridge were generally concerned a new bridge would increase traffic and visitors, impacting the environment and lifestyle.

The concept design provides a long-term solution for a safer, more reliable transport network.

Crash risk and severity are reduced because the traffic on each bridge is travelling in the same direction, with additional lanes or shoulders available to help avoid or pass incidents. Crossing points on the roads that approach the bridges enable traffic to transfer between bridges if required when incidents or maintenance works occur.

The concept design is a sustainable, flexible, and cost-effective solution.

Fully utilising the existing bridge as a long-term operational traffic bridge is a sustainable approach to managing the transport network. This reduces the width, cost and impact associated with constructing a new bridge.

This is in comparison to a new 4-lane bridge, with active transport on the existing bridge, which provides similar safety and reliability improvements, but at a higher cost. Strategic cost estimates indicate a new 4-lane bridge could cost up to 20 per cent more with a greater environmental footprint due to the wider deck and significant retrofitting of the existing bridge to align with current active transport and accessibility standards. Cost assessment is continuing as technical development of the concept design progresses.

The new bridge has wider lanes and shoulders and can provide a safer and reliable stand-alone connection for 2-way traffic and active transport if the existing bridge is closed due to an incident, emergency or maintenance.

The concept design aligns with the future vision of 4 lanes on Caboolture-Bribie Island Road and provides a flexible and cost-effective approach to investment, by delaying the need to provide a wider bridge until the existing bridge has reached its service life. The new bridge can be further widened at that time to provide four traffic lanes and an active transport path.

What will the new bridge look like?

TMR understands that while a new bridge must be functional and structurally sound, its design should consider the local landscape. Community feedback requested that a new bridge reflect the character of the existing bridge. TMR is proposing a simple bridge structure with a 2-column pier arrangement. Specifics such as how headstocks, balustrades and barriers will look, and treatments such as patterns, colours and textures will be considered during detailed design. Landscaping near the bridge approaches on the island and mainland will be included. (A headstock is a part of the bridge structure that supports the bridge spans and transfers the bridge load to the pier below.) Feedback will be incorporated when the design progresses.

How high will the new bridge be?

The new bridge is estimated to be up to 4m higher than the existing bridge at its highest point (near mid-channel). The detailed design phase will consider this further with the aim of reducing the bridge height if possible. The increased height accommodates additional structure depth, facilitates drainage and maintains clearance for the navigation channel with consideration for expected sea level rise due to climate change.

What will views be like?

The new bridge will be the primary view from northern areas of Bribie Island and the mainland and both bridges will be visible from southern areas. Views for active transport users will be of the Glass House Mountains, Pumicestone Passage, Bribie Island, the mainland and the eastbound traffic lanes. Views on the new bridge will be of the active transport path, Bribie Island, the existing bridge, and the passage. Views on the existing bridge will be of the new bridge, the mainland and the southern passage.

Feedback varied between requests to maintain views and requests to limit views for drivers to improve safety. Pelicans will be seen from all areas with perches that overhang the water located on the new and existing bridges.

When will the new bridge be built?

Timeframes for design and construction are not currently known. Funding will be considered in the future against other transport infrastructure priorities across the state.

Will peak period congestion move from the bridge to adjacent roads?

The existing bridge does not generally contribute to traffic delays during peak periods. Travel delays are primarily experienced at Benabrow Avenue and Sylvan Beach Esplanade intersections during peak periods.

Will Benabrow Avenue be upgraded?

Benabrow Avenue is the responsibility of City of Moreton Bay. The development of a bridge concept design will provide certainty to help council to consider the local road network and prepare for the future development of a new bridge.

Will Caboolture-Bribie Island Road be duplicated before the new bridge is built?

The concept design includes 4 lanes between Bestmann Road East and Benabrow Avenue. The Queensland Government has a strategy for progressive upgrades to provide four lanes along the length of Caboolture-Bribie Island Road. Upgrades are undertaken as funding becomes available and are generally sequenced to progress from west to east. Further information is available here.

Was active transport on the existing bridge considered?

Yes, the option of active transport on the existing bridge alongside a new 4-lane traffic bridge was considered. This option would cost more and involve additional environmental and community impacts due to the need for a wider bridge to support 4 lanes. Also, significant retrofitting of the existing bridge to align with current active transport and accessibility standards would be required. The existing bridge can continue to be fully utilised as a traffic bridge. This is a sustainable solution that provides for long-term transport needs.

Why not build a bridge between Toorbul/Donnybrook and Banksia Beach/White Patch?

This would not address the safety, reliability and active transport issues for the existing bridge and would involve impacts on other roads, communities (including land impacts) and marine areas. The location next to the existing bridge provides the best connection to the supporting road network, utilises state-owned properties, and links existing development and community facilities.

What needs to be done to the existing bridge to keep it operating?

The existing bridge can continue to be used for traffic for the foreseeable future. The bridge deck will be line-marked to provide 2 westbound traffic lanes. The ongoing maintenance program will include monitoring the piles for progressive encasement to ensure the good condition (durability) of the bridge foundation continues. (A pile is a concrete post that is driven into the ground to act as a leg or support for the new bridge.)

How have environmental impacts been considered?

The concept design is a sustainable approach to managing the transport network by continuing to use the existing bridge. This reduces the width of the new bridge, and its marine footprint and helps manage construction and operational impacts. Flora and fauna studies were undertaken during business case investigations to consider local habitats and species, and an Environmental Management Plan is being prepared. Detailed design and construction phases will undertake further investigations to develop environmental management measures. More information on how TMR undertakes sustainable environment management is available here.

How long will construction take?

Construction is expected to take around 2 years. This will be confirmed during future project stages and TMR will keep the community informed.

Will traffic noise increase and will noise walls be included?

Investigation of traffic noise is ongoing. While traffic volume is the key cause of traffic noise, traffic is not expected to grow greatly. However, because the new bridge is higher, traffic noise is expected to change.

Noise walls are not proposed to be included on the new bridge. Land-based noise walls are being considered. TMR will engage with the community regarding noise walls during future stages.

Will a toll be used to pay for the new bridge?

No. It is government policy not to place tolls on roads where there is no alternative route.

What happens if the existing bridge is decommissioned?

The existing bridge can be used for the foreseeable future as a long-term traffic bridge. TMR will continue to monitor the condition of the existing bridge and ensure appropriate maintenance works are completed. The proposed concept design can be widened to provide additional lanes in the future and TMR will plan for this before decommissioning of the existing bridge is required.

How will consultation results be used?

Feedback has helped develop the concept design by understanding key community concerns and requests and incorporating these into design features where possible. The feedback received can also be used during detailed design and construction phases.