How do cattle guards work?

Cattle guards are structures placed at the entrances of pastures or roads to prevent livestock from crossing while allowing vehicles to pass. They consist of a series of heavy bars or grates set in a trench, creating a barrier that cattle cannot easily step over due to their inability to gauge the depth and distance between the bars. The design deters animals from attempting to cross, as they perceive the guard as a risky obstacle. This helps keep livestock contained without the need for gates that require manual operation.