lifeguard -
A sturdy metal bracket affixed in front of each of the leading wheels of a train to deflect small objects away from the wheels to prevent derailment.
Wikipedia
A lifeguard is a person responsible for overseeing the safety of the users of a body of water and its environs, such as a swimming pool, a water park, or a beach. This differentiates them from life savers who partake in similar activities as a sport or practical life skill. Lifeguards are qualified strong swimmers, trained and certified in water rescue, using a variety of aids and equipment depending on requirements of their particular venue, and first aid.
