What is the maximum allowable speed deviation during a speed indicator check at speeds below 30 MPH?

The maximum allowable speed deviation during a speed indicator check at speeds below 30 MPH is ±3 MPH. This standard helps ensure that the speed indicators used in locomotives are accurate to a specific degree, which is crucial for safe operations. Maintaining a deviation limit of ±3 MPH ensures that trains can operate safely under varying conditions while prioritizing the safety of both the crew and infrastructure. Accurate speed readings are essential in preventing accidents and ensuring compliance with operational rules.

In a scenario where speeds are below 30 MPH, a deviation of more than 3 MPH could lead to significant operational risks, including the potential to exceed speed limits in restricted areas. This is why regulations set this specific threshold, allowing for manageable and safe operational flexibility, while still requiring adherence to speed safety protocols. The emphasis on accuracy in speed indicators is part of broader safety practices within the railway industry, showcasing the importance placed on rigorous compliance measures.