What initial action should be taken when responding to a transportation accident?

In responding to a transportation accident, the correct initial action is to assess the number of vehicles involved. This assessment is crucial for several reasons. First, understanding the scale of the incident helps determine the complexity of the situation, including the potential for multiple casualties and the need for additional resources. It informs the incident commander about the scene dynamics and what kind of tactical response is necessary.

Assessing the number of vehicles can also aid in evaluating the potential hazards, such as fuel leaks or hazardous materials, which might not be immediately visible. This initial assessment can dictate whether to activate additional emergency protocols, call for additional resources, or identify the need for specialized teams.

The other actions listed, although important in specific contexts, do not take precedence over this initial assessment. Turning on radiation meters may be relevant if there is a known risk of hazardous materials, but it is not usually the first step at a typical accident scene. Calling for additional resources comes after the assessment shows that more support is needed, while initiating rescue operations would also follow an initial evaluation of the situation and the need for immediate rescues based on the number of vehicles and victims present.