Either the path has subsided, or the bridge has grown 5 or 6 inches since it was built. It's a terrible trip hazard for pedestrians, and I wouldn't want to crash into that step at any speed on a bike. It's a trap for the unwary.
I logged it with the RTA yesterday, asking them to build up the footpath or to install a ramp at both ends of the bridge. They might come back and say that it is a local council problem, which could be a problem as Lane Cove Council doesn't seem to think much of anyone who isn't in a car.
It's small things like this that we often overlook, considering them too petty to take up with the appropriate authority. But many small things soon add up to create a big problem, so I like to try and ensure that the little things are dealt with.