A player uses the crowbar to pull up track pieces by hitting them with the crowbar. Right-clicking with the crowbar on a rail will adjust it, which, in most cases, means reversing its direction (important for Booster rails and Transitions). Some rails will open a GUI when right-clicked with the crowbar, allowing the player to adjust its settings. Right-clicking on an Advanced Loader, Cart Dispenser, or a Detector will turn the block to face the side clicked on.
The crowbar can also be used to link carts together into a train. See Cart Linking for more information.