What must vehicles displaying a diamond-shaped sign do before crossing railroad tracks?

Vehicles displaying a diamond-shaped sign are indicating that they are approaching a railroad crossing. The correct action at such crossings is to stop before crossing the tracks. This is a safety measure, as it allows the driver to carefully assess the situation and ensure that no trains are approaching from either direction. A full stop provides the driver with the best chance to avoid potential collisions, given the speed at which trains travel and the difficulty of judging their distance and speed.

While slowing down and looking for trains could be seen as an appropriate precaution, simply looking is insufficient; stopping ensures that the vehicle can properly evaluate the situation before proceeding. Proceeding with caution without stopping may also lead to dangerous situations, as it does not guarantee the driver will have enough time to react to an oncoming train. Moreover, speeding up to cross quickly is not safe behavior, as it increases the risk of an accident. Therefore, stopping before the tracks is both a legal requirement and a critical safety practice at railroad crossings.