Performance, perceived safety and comfort of the alternating tread stair

This study determined the perceived safety and comfort of an alternating tread stair and a conventional ship's ladder. The alternating tread stair and the conventional ship's ladder were also compared with respect to travel time and missteps. Subjects in military uniform ascended and descended both devices under load and no-load conditions. In the load condition, subjects performed trials while carrying a 9-kg tool-box; in the no-load condition, trials were performed without the tool-box. Results indicate that the alternating tread stair is perceived to be safer and more comfortable to use. Moreover, the alternating tread stair had significantly fewer missteps.