This paper considers variable pitch axial flow fans for application in Vehicular Tunnel Ventilating systems. The fan design is of German origin where it is considered to represent the "state of the art", matured over more than two decades of operating experience. Its utilization for tunnel ventilating systems in the U.S.A. appears to be justifiable. The design and its performance are described. Three major areas--energy conservation, space requirements and number of pieces of equipment, provide the largest savings potential and make this fan design most attractive.