I can't see any recently installed uphill-graded runaway sidings on Google maps, although a lot of the line is shaded by trees. Perhaps they're getting confused with similar facilities for trucks on the Illawarra escaprment roads.

There was a spectacular runaway in 1963 where loco 4528 lost 17 wagons on a derailment coming down the mountain, then took the remaining 17 wagons on a wild ride out of control down to Unanderra where the signalman switched it onto a dead end siding (perhaps this is the same one?) where it shed the remaining wagons at the station then vaulted a creek before coming to rest in the soil. There was later a grade-separation of the level crossing at Princes Highway in conjunction with the aborted project to Maldon. A few loco crew have been killed on the mountain since the 1960s, from collisions and landslide.

And yes the 1993 bridge at Woolcott St Lavendar Bay is from Dombarton. One of the delights of the old Tin Hare service from Wollongong to Moss Vale was that the guard would let you out at the stop at Summit tank to look at the spectacular view of the Illawarra coast from the nearby lookout.

Tony P