Analysis of Bus Driver Perception-Reaction Times and Deceleration Behavior for Design of Traffic Signal Clearance Times

The research presented in this paper quantifies and models bus driver perception-reaction times (PRTs) and deceleration levels at traffic signalized intersections for use in the design of traffic signal clearance times. A total of 864 stop-run records were collected as part of the research effort for a 56 km/h (35 mi/h) free-flow speed where participant bus drivers encountered a yellow indication initiation at different distances from the intersection. The participant bus drivers were randomly selected in different age groups (under 40 years old, 40 to 64 years old, and 65 years of age or older) and genders (female and male). Using the gathered data, statistical models for driver PRT and deceleration levels were developed, considering roadway surface and environmental parameters, driver attributes (age and gender), roadway grade, approaching speed, and time and distance to the intersection at the onset of yellow. Effects of precipitation are included in the bus driver PRT and deceleration models using values derived from previous passenger car studies with the assumption that bus drivers are affected the same way as passenger car drivers. The resulting bus driver PRT and deceleration models have an adjusted R2 value of 0.16 and 0.87, respectively. Furthermore, a logit model was developed using field data and driver characteristics to classify and predict the probability of bus drivers either running or stopping at the onset of a yellow indication. The stop/run decision logit model produced an 87 percent correct stop/run decision prediction. The resulting PRT and deceleration models can be used in designing yellow indication intervals to accommodate for buses in the traffic stream.