Allowable emergency braking rates for APM vehicles

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Allowable emergency braking rates for APM vehicles

McGean, T.J.

There is no good single source of information on the maximum acceptable emergency deceleration for standing passengers on automated people movers (APMs). This paper researches the English language literature covering braking rates for rail, light rail and bus transit and compares it with APM practices in the United States. There is no black and white answer to the question of acceptable maximum emergency braking limits for standing passengers. When faced with automotive traffic problems or steep grades, transit operators have accepted levels of 0.3 or even 0.4 g. Verhicles operating at these levels have been accepted by the riding public despite experimental evidence which suggests lower values would be preferred. A number of the test conditions, including constraints on the ability of the person to adjust his or her feet to help maintain balance, have caused some researchers to challenge the experimental data. Present U.S. APM practice is to limit emergency braking rates to 0.32 g while reserving some seats for elderly or disabled riders. The available evidence indicates this to be a reasonable approach.