The disclosure is directed to a method and apparatus for characterizing an object protruding beneath a train traveling along a rail. The apparatus includes a tube having adjustable open upper and lower ends and an impeller for drawing a major water flow in either direction through the tube. The actuator body has first and second output members contacting the first and second extension parts of the lens receiving part at opposed ends thereof, and thereby expands, contracts and bends when power is applied. The air trunking has a longitudinal center axis, wherein combustion air flows in the first section of the port in a first direction of flow running in the direction of the longitudinal center axis.