Final answer:
A reasonable commuting distance for BAH protection is not clearly defined but could potentially align with the concept of an effective air defense perimeter, estimated at a radius of about 30 nautical miles. In a non-military context, a reasonable commuting distance is often subjective and depends on individual circumstances.
Step-by-step explanation:
The question regarding a reasonable commuting distance for BAH protection may refer to considerations for military service members in relation to housing allowance accommodations and the safe distance from potential military threats.
An effective air defense perimeter is generally estimated at a radius of about 30 nautical miles from a confirmed or possible surface-to-air missile (SAM) site. If we use this parameter as an analog for 'safe distance', it could inform decisions related to a 'reasonable commuting distance' under situations where BAH (Basic Allowance for Housing) protection is a factor. In non-military context, a reasonable commuting distance is often subjective; however, it typically falls within a range that allows for safe and timely travel to and from work.
The question about how far away a car must be before it is safe to cross and the equivalent distance in car-lengths is more related to traffic safety and driver's education. This can vary depending on the road conditions, speed limits, and the responsiveness of the pedestrian or driver.