The Transport and Main Roads department will design the bridges over the next six to 12 months, taking into account factors including the corrosive tidal environment they are in, assessment and design of the foundations and environmental impacts.
Full replacement costs of the bridges are yet to be assessed.
Funding for the project was much anticipated by the community, which is suffering from the restrictions imposed on the bridges by Main Roads due to pronounced deterioration.
The road agency reduced the original two lanes each way to one in each direction on Harbour Road and cut the speed limit to 40 kilometres per hour over the bridges after an inspection in March showed there was cracking and a loss of concrete around the pylons under the bridges.
Concrete barriers were installed to reduce the number of lanes, creating difficulties for motorists to merge.
Access restrictions were placed on mobile crane or special-purpose vehicle access and limits apply for heavy vehicles operating under special permits.
State Member for Whitsunday Jason Costigan said he acknowledged the inconvenience the restrictions had on the community but safety was the priority.
“This is not only an important link for Mackay city but also serves as a vital link between the Port of Mackay and the Bowen Basin,” Costigan said.
“More than $1 million worth of overall works will be undertaken just to prolong the life of the current structures for as long as possible.
“While the bridges will still require restrictions to be in place, this is still a better outcome than having no bridge, which is what would have happened if Labor had continued to ignore the problem.”