What is the primary reason why vehicles are placed Out-of-Service?

The primary reason vehicles are placed Out-of-Service is due to detected mechanical defects. Vehicles are critical to transportation safety, and any mechanical issues can pose significant risks to both the driver and other road users. When defects such as brake failures, tire issues, or engine problems are identified during inspections, the vehicle must be taken out of service until the necessary repairs are made. This measure is essential to ensure compliance with safety regulations and to prevent accidents that could arise from operating a vehicle in a potentially dangerous condition.

While other factors like insufficient fuel supply, exceeding weight limits, and lack of driver certification can affect a vehicle's operation, they do not directly compromise the mechanical integrity and safety of the vehicle itself. Mechanical defects are often prioritized in Out-of-Service determinations to ensure that all vehicles on the road are safe and fully functional.