Apologies for the poor photo. A dark brown mix of acrylic paint to represent aged rust has been applied to the rail sides and chairs.
A thin wash of the same colour was then applied to the sleepers before ballasting. There is nothing unusual about the method of ballasting. Ballast was applied dry and tidied with small brush. Once happy with how it looked it was wetted with water mixed with a small amount of either Isopropyl or a drop of washing up liquid added and applied with an atomiser spray bottle. A diluted mix of water and pva glue was then generously applied with a plastic pipette.
The first photo below shows the ballast dry and the second after it has been wetted.
Once the ballast had dried I added some more colour to simulate dirt and grime using weathering powders. Looking at the photo now it would probably benefit from a darker mix between the rails to simulate some oil and grease deposits and perhaps some more highlights on the chairs before I move on to the next stage.
Some additional weathering added with MIG Track Brown used to darken the rust effect on the chairs and a dark slate grey pastel to add some oil and grease deposits to the area between the tracks.
I'm much happier with the track now and can move on to adding some grass etc.