Modeling and verification of the kinematics of passenger falls on escalators

Abstract

Passenger falls on escalators are one of the major causes of accidents. Falls can either be passenger caused or escalator caused. Unplanned stops of escalators can cause passenger falls and consequential injury in the form of cuts, bruises, finger entrapment and, in certain cases, crushing leading to suffocation. In order to better understand the kinematics of passenger falls on escalators, MATLAB-based software has been developed. It simulates the effect of an acceleration signal on a rectangular block. The most important parameter of the rectangular solid block is the center of gravity ratio, which is defined relative to the axis around which the fall can take place. The model is then practically verified by subjecting an actual wooden rectangular block of a specific center of gravity ratio to an acceleration signal and taking a video of the fall. The acceleration signal is measured and fed into the model. The video is analyzed frame by frame in order to use time-lapse photography to compare the falling block with the output of the model. Good agreement has been achieved. Data on the human body is analyzed in order to arrive at an appropriate value of the center of gravity ratio for the human body. This value is further adjusted to account for variability in the human body, and expected human behavior, up to a value of 10. This result is then used to arrive at a limit on the maximum value of acceleration form the escalator braking system in order to prevent escalator-initiated passenger falls. Applying knowledge of the variability of the expected maximum acceleration from successive escalator stops is then applied to arrive at the final value of 1.16 m·s^–2 as the recommended value to be used as a design and acceptance value for escalator braking system performance in order to prevent passenger falls.