In alleys, what length of mast arm is typically used?

Mast arms used in alleys are typically designed to extend a certain length to support street lights or traffic signals while ensuring visibility and safety. A 3 ft length is often preferred because it strikes a balance between providing adequate projection over obstacles, such as buildings and utility poles, and minimizing the risk of interference with pedestrian movement and vehicular traffic.

This length allows for sufficient lighting coverage in the alley without creating too much overhang that could lead to safety hazards. A shorter length might not provide enough clearance or coverage, while a longer one could risk obstructing views or causing issues with traffic flow. Therefore, the 3 ft mast arm is commonly accepted as a standard in such environments.