Adding dirt and moisture

The walls put together and set on the base:

View from the street

View from the tracks

I used light grey and black Bragdon weathering powders to blend colors together and add some patina to the wall sections (compare to yesterday's post).
The effect is startling. I can almost smell the moisture creeping up in those walls...

Added appropriate dirt and weathering

I later realized that this is better done when the model is put together to get a consistent look around the corners. However, doing this with the walls flat on the bench allowed me to experiment with the process, so it was still useful this way and I can apply what I learned the next time I use this technique.