IAP Project: Evaluation of the interaction between horizontal and vertical alignment on rural two lane roads

Project Description This research study was sponsored by NCDOT through FHWA SHRP2 Implementation funds. This study proposed to provide valuable information about how drivers interact with roadway under various combinations of vertical and horizontal alignment. The Following were research questions investigated: 1.) Are there differences in speed profiles, lane keeping measures, and other driver-control variables as vehicles approach and maneuver through roadway segments with different combinations of vertical and horizontal alignments? How do these differences relate to high, medium, or low risk conditions that can be defined using current crash modification factors CMFs from the FHWA HSIS? 2.) How is a driver's ability to recover from a run-off-road event affected by the roadside characteristics under different combinations of vertical and horizontal alignments? 3.) Is there a difference in driver behavior or responses in daytime versus nighttime under different combinations of vertical and alignments? 4.) How is driver behavior affected by closely spaced curves and grades compared to isolated curves and grades? 5.) How is driver behavior affected by the familiarity of the road, e.g., is there a difference in behavior between drivers who use the road often versus drivers who may be visiting the area as a tourist? Data Request Scope The dataset received used the Roadway Information Database (RID) to identify SHRP2 naturalistic driving study combinations of horizontal and vertical alignment with high, medium, and low risk. UNC’s provided 10 sites in each of five combination of horizontal and vertical alignment. For each site, data was generated for 25 trips. Time series data for each different trip segment included front video that was linked by name to the time series data file. Data Specification The following information was provided: DAS Timestamp, FILE_ID, vtti.lane_distance_off_center, vtti.left_line_right_distance, vtti.right_line_left_distance, vtti.left_marker_probability, vtti.right_marker_probability, vtti.lane_width, vtti.speed_network, vtti.speed_gps, vtti.heading_gps, vtti.gyro_z, vtti.steering_wheel_position, vtti.pedal_brake_state, vtti.pedal_gas_position, vtti.accel_x, vtti.accel_y, vtti.latitude, vtti.longitude, Eye glance information: on the road, roadside, rearview or side mirrors, and inside the vehicle, cell phone, etc. o Potential distractions (e.g., eating/drinking, personal hygiene, cell phone or other hand held devices, other). The following driver demographic information was also provided: Driver Demographic Questionnaire: Participant ID, Gender, Age Group, Education, Marital Status, and Income. Driver History Questionnaire: Participant ID, Average Annual Mileage, Years Driving, Number Violations, Number Crashes, Crash 1 Fault, and Crash 2 Fault. Insurance Status Driver Knowledge Survey: Participant ID, Night driving, Merge signs, Curve signs, Yellow lines, Number correct. Visual and Cognitive Tests: Participant ID, Impairment level – VMI, Impairment level – visual search, and Impairment level – UFOV. Risk taking questionnaire: Participant ID, Run red lights past 12 months, Take Risks for Fun Often, Speed for Thrill Often, Road rage past 12 months, Speed 10‐20 mph over, and Speed 20+ mph over. Driver behavior questionnaire: Participant ID, Run red light, Tailgating often, Often road rage, and Disregards speed limits. Medical conditions and medications: Participant ID, Multiple medical conditions, Multiple medications, and Gave up driving. The following vehicle information was provided: Vehicle Width.