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A study was conducted to evaluate the usability of the range of ramp slopes allowed under the current ADA accessibility guidelines. One hundred seventy-one subjects of all ages and using different types of mobility aids traversed a 30-foot ramp varying in slope from 1:8 to 1:20. Data were recorded for pulse rate, energy expenditure, rate of travel, distance traveled, and the location of rest stops. Findings show that among all subjects only a few manual wheelchair users had difficulty traversing all 30 feet in ascent, even on slopes as steep as 1:8. Based on these results, changes to the technical requirements for ramp slope and length cannot be recommended at this time.
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Sanford et al. (1997) studied this question.
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