Warning signs, object markers, construction and railway signs

Most warning signs are yellow diamonds, and they all answer the same question: what is about to change? A curve, a merge, a lane ending, a narrowing bridge, a slippery surface, a steep hill, signal lights, a crosswalk, deer, falling rock. Some carry an advisory speed — that number is a recommendation for the hazard shown, and it is often well below the posted limit.

Object markers are a separate case. They are mounted on the obstruction itself, not before it, and they tell you which side to pass on: keep right, keep left, or either.

Construction signs are orange. In a work zone you must obey the posted speed, follow the instructions of a traffic-control person, stay well back from equipment, and pass only when it is safe. Fines for speeding in a work zone are posted on their own sign for a reason.

Railway crossings end with one rule: you must always yield to trains. A crossing may be marked with signs, pavement markings, or mechanical and electrical devices. Where a gate is fitted, stay stopped until it is fully raised — not until it starts to move.