An elevator installation has at least three vertical elevator shafts arranged adjacent to one another, at least one boarding zone and a plurality of individually movable elevator cars. The nose foam has first and second opposing major surfaces and a thickness T that extends from the first major surface to the second major surface. In addition, the top cross-member provides a vehicle platform for moving a disassembled unit with built-in wheels, a handle, and stacking structures to support the other members. An alarm may then be triggered when the filter efficiency falls below a pre-determined value.