The rest of us must resort to some sort of trick. The Truth Table is a semi-graphical way of viewing the components of any logical expression. Used properly, it will show you instantly how to combine the various elements into a single equation. The sixteen cases thus reduce to only 5. It doesn't take much thought to realize that you can add global disable terms just by ANDing more variables with the final equation.
Truth tables are particularly valuable for identifying non-obvious relationships.
Suppose this example resulted in 13 conditions where the train moved, instead of just 5. If you skipped the truth table exercise you'd probably come up with a hideously complex program that dealt with all 13 conditions. The great simplification brought to bear by a truth table often obscures the truths being worked on. Great job security, but a terrible disservice to your successors. Use the table as a documentation device.