Some observations and thoughts on the mud holes,
When a month or probably more ago they started to remove the ballast from the ends of the sleepers I noticed something odd.
On a good number of the sites this had been done it looked like it had cured the imediate problem. Now I stopped and had a look and it looked like the sleepers were sitting in a trough of mud surrounded on all sides including underneath by clean ballast.
Another thing I noticed was there were three mudholes on Steel decked Ballast top bridges.
Now I discussed this with a long time track worker and he said the ballast that was being used was of poor quality and was powdering under the concrete sleepers due to the traffic.
Another point worth mentioning is that Violet Town Quarries in the current orders for the ballast was told to supply a much higher quality and a much harder ballast whichs was at a somewhat higher in price.
Now it looks like at least in some parts the ballast is failing. Now I am not claiming this is the whole problem there is clearly some base damage but it looks like one must keep an open mind on this problem.