Ballast is the gravel base upon which the track ties sit.
A tie is a wood or concrete crosspiece to which the rails are anchored. It is one of the two main components to a railroad track, which are the rails and the ties.
A turnout is a switch or a branch-out in the track. See the picture below for a visual…
Guardrails are an extra set of rails placed on the inside of the running rails used by the train (see photo below). This is safety feature to help keep a derailed train from veering too far away from the track. This is very common across bridges. Guardrails are especially recommended for your bridge sections that have a height at least 2 feet from top of the rail to the ground.
Deck Girder Bridge: A girder is a support beam for a bridge. Decking (using ties) is then constructed on top of these beams. The entire weight support of the bridge are the girders under the decking. So a deck girder bridge is one in which the track is above the support. Compare this to a truss bridge where the main structural support is above the rails.
Simulated rust is actually brown spray paint applied to the rails, rail plates, and bridge joints, to make them appear rusty, just like the prototype.
A handcar is a self-propelled railroad vehicle, through the use of a manual crank or lever.
A cart dock is a train siding that ends in a loading/unloading port where a rolling stock item can be loaded from the tracks onto a cart that can be rolled into a garage, barn, shed, etc., for storage out of the weather. This is an alternative to a fixed train shed and is often preferred because of it flexibility and multiple uses.
Rolling stock is any piece of equipment that rolls on the rails. This includes (but is not limited to) a handcar, a freight or passenger car, or a locomotive.
Crossbucks is a warning signal for road crossings featuring alternating red lights and a sign shaped like an X with the words “RAILROAD CROSSING”. See photograph below.