Geometric Design Speed Characteristics on Freeway Ramps

Project Description This study examines driving data on freeway ramps from the SHRP2 NDS - speed profiles along with selected driver and vehicle variables - and compared that data to the design characteristics of the ramps traveled during the study. In addition to the SHRP2 data, the research uses detailed information from the road agencies in the SHRP2 participating states (New York, Indiana, Florida, North Carolina, and Washington) to document the ramps' design characteristics. The objective of the comparison was to identify relationships between the factors used to select freeway ramp design speed (e.g., radius, superelevation, etc.) and the actual speeds of drivers traveling on those ramps and their associated behaviors (e.g., brake/accelerator use, steering wheel angle, etc.). The findings from the comparison will then be further compared to the findings from recent research to identify similarities, differences, and potential topics for future research or considerations for changes to existing design guidance. Data Request Scope The delivered data includes 10,834 CSV files of timeseries data. Data Specification Timeseries variables: System.Time_Stamp vtti.timestamp vtti.file_id vtti.abs vtti.accel_x vtti.accel_y vtti.accel_z vtti.esc vtti.gyro_x vtti.gyro_y vtti.gyro_z vtti.lane_width vtti.left_marker_probability vtti.odometer vtti.pedal_brake_state vtti.pedal_gas_position vtti.right_marker_probability vtti.speed_gps vtti.speed_network vtti.steering_wheel_position vtti.traction_control_state --