TATHAM BRIDGES REPLACEMENT

Client: Richmond Valley Council

Service Type: Bridge and Road Design

Location: Deep Creek and Spring Gully bridges are located on Casino-Coraki Road crossing Shannon Brook and Spring Gully respectively, adjacent the township of Tatham, around 15 km southeast of Casino.

The Problem: The bridges are in poor condition and had been assessed as only suitable for GML vehicles, the speed limit has been reduced to 60 km/hr from 100 km/hr. Due to the findings of the load rating and the importance of the Casino-Coraki Road, in particular during flood events. During the February-March 2022 flooding event that affected many NSW towns in this area with maximum water heights the Casino-Coraki Road was one of the first roads available to access towns including Lismore.

The Timeframe: Council required urgent action to ensure not only to reopen the bridges to modern load standards but also to raise the bridges slightly to improve network reliability, in particular during a natural disaster – improving resilience.

The Outcome: Council with the assistance of Bridge Knowledge and other local consultants was able to produce a detailed design and estimate for the upgraded crossings to ensure a funding submission could be made to the State Government within a tight timeframe. Bridge Knowledge contributed with bridge and road design with the new structures are anticipated to be constructed offline to the existing bridges so they can be used as temporary crossings during construction. It is proposed that the new structures will comprise Super T girders (T5) with a width of 8.4 m between barriers to accommodate two traffic lanes. Deep Creek bridge is proposed to be three spans at 38m, 38m and 20m and Spring Gully bridge is proposed to be a single span of 38m. The proposed works include a realignment of the existing road to improve safety and the provision of upgraded intersections and a dedicated bus stop for the local school buses.