What safety feature is essential for containers used for transporting hazardous materials?

Secure locking mechanisms are essential for containers used for transporting hazardous materials because they ensure that the contents do not accidentally spill or leak during transit. These mechanisms help prevent unauthorized access to the container, ensuring that only trained and authorized personnel can handle the materials inside. Proper locking systems are critical in maintaining safety protocols and regulations, especially given the potential risks associated with hazardous materials, which could lead to environmental damage, health hazards, or regulatory violations if not properly secured.

While ventilation holes may assist in reducing pressure or preventing the buildup of harmful gases, they are not universally necessary for all hazardous materials and do not address security concerns. A color coding system helps in identifying the nature of the contents but does not enhance physical security or containment of the materials. All-weather tires, although important for vehicle safety, are not directly related to the structural integrity or security of the containers carrying hazardous materials.