What have you tried so far?
Please review this post How to get help on the Dynamo forums
Personally, I think this would be better to do this in Revit than Dynamo - what happens if your sleepers change?
Set up your sleeper family with a reference planes for the centreline of the rail anchors and the end offsets. Create a line based family with the anchor family using a spacing formula.
Place anchor line using the sleeper face as the host. Align the anchors to the reference planes in the sleeper.
You could group this or create a nested family and you have a fully parametric solution