Multitasking additional-to-driving: Prevalence, structure, and associated risk in SHRP2 naturalistic driving data

Area of Science:

• Traffic Safety Research
• Human Factors in Driving
• Behavioral Analysis

Background:

• Multitasking additional-to-driving (MAD) is prevalent but its association with crash risk requires quantification.
• Understanding the structure and prevalence of MAD in various driving conditions is crucial for safety interventions.

Purpose of the Study:

• To analyze the extent of driver engagement in multitasking additional-to-driving (MAD) under diverse conditions.
• To determine the odds ratios (ORs) of crashing associated with MAD.
• To explore the structural patterns and co-occurrences of MAD behaviors.

Main Methods:

• Analysis of data from the Second Strategic Highway Research Program Naturalistic Driving Study (SHRP2 NDS).
• Quantification of MAD prevalence in normal driving and safety-critical events.
• Calculation of odds ratios (ORs) for crash risk associated with MAD.
• Sensitivity analysis using grouped task definitions and development of a visual representation of multitasking.

Main Results:

• MAD occurred in 11% of control segments, escalating to 22% in crashes/near-crashes (CNC), 26% in Level 1-3 crashes, and 39% in rear-end striking crashes.
• Odds ratios (ORs) for MAD significantly increased crash risk: 2.38 for CNC, 3.72 for Level 1-3 crashes, and 8.48 for rear-end striking crashes.
• Task co-occurrence patterns varied by event type, with distinct interactions observed in CNC versus control segments.

Conclusions:

• The prevalence and type of secondary tasks drivers engage in vary significantly across different driving event types.
• Multitasking additional-to-driving (MAD) is associated with elevated risk across all safety-critical events, most notably rear-end striking crashes.
• Findings confirm that the performance decrements observed in simulator studies of MAD are reflected in real-world crash data.