Estimating uncertainty and Misery (Index) of the paratransit experience

Abstract

Transportation access significantly impacts inclusion, well-being, and health. However, people with disabilities often struggle to use fixed-route transit due to mobility challenges. The Americans with Disabilities Act (ADA) mandates complementary paratransit services, but these services remain inefficient and unreliable.

This study analyzes 1.16 million paratransit trips in the Denver region, comparing travel time reliability with car travel times using FHWA’s reliability indices: the Planning Index, Buffer Index, and Misery Index. We normalized the data using the paratransit user trip rate (PUTR), a ratio of trip distance to trip time, and conducted user interviews to provide insights into lived experiences and perceptions of service quality.

The results suggest significantly lower travel efficiency compared to car travel, with paratransit users experiencing much longer and less predictable trips. More specifically, paratransit trip times are highly volatile, requiring riders to plan for worst-case scenarios to ensure on-time arrival 95% of the time. On average, paratransit users must allocate 3 hours for trips that would take 20–30 minutes by car. The unpredictability of travel forces riders to overbudget time, significantly impacting daily mobility and quality of life.