Abstract
A series of experiments were conducted to identify the factors that could aid passengers in remaining seated during an emergency deceleration of an automated transit system. Sixty subjects, representative of three anthropometric levels, underwent various levels of deceleration in an instrumented vehicle controlled by an automated braking system. The independent variables examined were seat orientation and tilt, seat contour and covering, footrests and armrests, and rate of change of deceleration (jerk). The primary dependent variables were the deceleration levels at which subjects moved from sensors that were imbedded in the experimental seat. Movies were taken and subject comfort ratings were also obtained.
The major results indicated that forward-facing subjects sustained higher deceleration levels without being dislodged than subjects sitting at small orientation angles of 15° and 30°. A foot-rest contributed to greater retention of forward-facing subjects as did a seat tilt of 12° back. The maximum deceleration level for retention of 84 percent of the forward-facing passengers sitting on a seat tilted back 12° and using a footrest was 0.36 g.
Jerk was found not to be a factor in dislodging subjects during the onset of the emergency stop. It was, however, a factor in the perception of comfort. Subjects reported being more uncomfortable at higher jerk levels. Providing a warning to the passengers of an impending stop may aid them in sustaining higher deceleration levels.
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