Evaluation of combinations of tread and rise in regard to safety on stairs Part 3 永 田 久 雄 * Hisao A[ A GA TA Pedestrians are liable to have accidentS while descendi 皿 g stairs , because of unsu 正 table di皿 ensions in the tread and rise . The dimensions of tread and rlse are oonsidered to be evaluated by pedestrians thcmselves . IIl this paper, the sensory tes 【 s for difficulty in descending stairs were applied to evaluate many combinations of tread and rise . The results of sensory tests were

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... ua 面 fied by one of the psychometric methods , spccifically the method of successive categories . Ten young males ( average ages 21 . 0 ) , ten young females ( 19. 7 ) and ten male eldeTly subjects ( 71 , 2 ) assessed 42 combinations of tread and r 正 se in des nding stairs . The female grt )up wore 4 lypes of footwcar , differing 正 n the heel height . Dimensions of tread and risc with less diff / iculty in des nding stails cxisted in dcfinitc combinations , around 29 -30 cm tread and l8 cm rise foT lowcr heels , and around 30 cm trcad and 15. 5 cm rise for higher hccls . Psychological pressures increased as nleasuremcnts deviated from these combinations of tlead and 丁ise . A practical value index is suggested in this pape 了,