How has the flooding issue been addressed?
The proposed upgrade crosses the Macleay River floodplain near Frederickton. A detailed assessment of flooding behaviour and the most appropriate bridging configuration was undertaken in consultation with the flooding group, local landowners and other stakeholders. The process to determine the optimum length of bridging across the Macleay River floodplain involved modelling of various bridge lengths and configurations, as well as input from the flooding group. This included evaluation of various lengths of partial bridging and the full bridging option. The flood modelling assessed the characteristics of flooding during various scenarios including the 1-in-13-year, 1-in-20-year and 1-in-100-year flood events.
Bridge configurations were assessed considering afflux (the increase in the level of water caused by changes to the flow behaviour), flow velocity, changes in time and depth of flooding, capital cost, geological conditions, surrounding land uses, heritage and potential flood damage.
Based on this modelling, the optimum length for floodplain bridging was determined to be approximately 2.2 kilometres comprising three main bridges. These bridges will cross the southern end of the floodplain, South West Rocks Road and the Macleay River. There will also be a small bridge crossing the existing highway east of Frederickton.
Frederickton interchange
The Frederickton interchange has a single south-western connection to the existing highway. This interchange layout reduces the impact of the project on the floodplain and the floodwater flow paths. This means that less bridging is needed, and there will be less impediment to floodwaters. The design also minimises the visual impact of the interchange.
Stuarts Point Road interchange
The Stuarts Point Road interchange is a full interchange near Eungai Rail, with connections to the existing highway, Eungai Rail and Stuarts Point. It provides traffic movements similar to the existing intersection arrangements.
Alignment adjustments
The alignment of the highway was developed considering various community, environmental and engineering issues.
The alignment has changed at Pola Creek, Collombatti and Barraganyatti to address impacts on water courses, agricultural operations, threatened species and local amenity.
Crescent Head Road
Crescent Head Road is proposed to pass over the proposed highway. This reduces the amount of soil needed for embankments and lowers the highway, thus reducing noise and visual impacts in the East Kempsey area.
Rest areas
Rest areas for both north and southbound traffic are proposed on the southern edge of Tamban State Forest.
The rest areas require minimal clearing of native vegetation and are situated away from sensitive land uses. They provide convenient opportunities for both light and heavy vehicles to stop and rest. The rest areas are located a suitable distance from other designated stopping areas.
Back to top