Is the Douglas Park Bridge in trouble?
If so, then the likely cause is longwall mining in the nearby coal mines.
Douglas Park Bridge - northbound
Douglas Park Bridge - southbound
Drilling Rig - in situ,
under the Twin Bridges
Official Job Number and description
Core Sample - trays - various marked depths
As you can see, the RTA has hired a drilling company to test the rock base under these Twin Bridges, at Douglas Park. Why?
Well, there has already been longwall mining conducted in the area. There is further longwall mining likely to commence in several months time. So, it would appear that they are checking to see if fracturing of the bedrock foundations of the Bridge has already occurred. Has it? I understand that it is very likely that it has occurred - but I am not an engineer.
Alternatively, they are assessing the risk of future fracturing of the bedrock foundations, once the new longwall mining commences.
Meanwhile, from what you can see, in today's traffic flow restrictions, it is reasonable to assume that the RTA is sufficiently worried about its Douglas Park Bridges to limit the traffic loading on the Twin Bridges.
Let us hope that they can exert enough influence on the mining companies to prevent longwall mining in the area. For subsidence, should it occur, could render this bridge unsafe. The social, physical and economic costs of these Bridges, should they need to be to be closed for repairs could be extraordinary. These bridges are an enormously critical part of the Australian road infrastructure.
Do you think I am kidding? You do the sums on how much freight goes over these Twin Bridges, each day, going to and from Sydney from Melbourne and Canberra, and other parts of the country.
Further damage to the Twin Bridges is surely preventable. It just requires the NSW Minister for Transport to step in to prevent further mining in the area. He just needs the balls to stand up to Frank Sartor, Minister for Planning, who is the guy who authorises these longwall mining activities. No worries.
These Twin Bridges span the Nepean River, at Douglas Park. The Nepean River rises at Kangaloon, just south of Robertson