CMV Studies: Crash Causation and Safety Belt Use

CMV Studies: Crash Causation and Safety Belt Use Tapan K. Datta, Ph.D., P.E. Professor Wayne State University Transportation Research Group March 13, 2007

Crash Statistics in Michigan Source: www.michigantrafficcrashfacts. org

*CVMT was assumed to maintain a 7.23% growth rate per year Source: www.michigan.gov/mdot (Total VMT for 1999-2005 and CVMT for 2001 and 2005)

CMV Fatalities • 5,000 Average Fatalities per Year involving Commercial Motor Vehicles (CMV’S) across Nation* • 20% were Occupants of Commercial Motor Vehicles • 80% were Passenger Vehicle Occupants • 80% of the CMV Occupants killed were due to non-use of safety belts * Source: “Safety Belt Usage by Commercial Motor Vehicle Drivers Final Report”, November 2003, Federal Motor Carrier Safety Administration

WSU’s 2004 Truck Safety Study • Phase I- Meta Analysis • Review and synthesize the literature on truck safety for long-term impacts of: • Driver training, enforcement and regulations • Identify technology options • Phase II- Evaluation Plans for: • Specialized Truck Enforcement Team (STET) Program • Driver Performance Measurement (DPM) Program • Decision Driving Course Program • Safety Audit Program • Review and synthesize the literature on evaluation studies • Identify data needs to conduct evaluation studies

CMV Crash Causation • Percent of incidents due to drivers’ faults is greater than vehicle defects, environment or other causes • Gou, et. al. study in Montreal, Quebec, 1999 • Toth, et. al. study in the USA, 2003 • Craft & Blower study in the USA, 2003

Causal Factors of Multi - Vehicle Car - Truck Crashes 100 90 80 76% 74% 70 60 Truck Crashes (%) 54% 50 40 39% 30 20 18% 10% 8% 10 8% 6% 3% 4% 0% 0 Driver Vehicle Environment Other/Unknown

CMV Crash Causation • The following predominant causes of car-truck crashes were identified from the state-of-the-art review • Excessive Speeding • Driver Inattention • Following too closely • Failure to stop/yield • Failure to stay in lane/improper merge • Driver Fatigue

2003 CMV Safety Belt Use Study • Safety Belt Usage for CMV Drivers Study conducted by USDOT and FMCSA in 2003 • 12 State Sample (not including Michigan) • One County Group from each State • 117 Observation Sites

2003 CMV Safety Belt Usage • USDOT and FMSCA Study Findings • 3,909 Commercial Motor Vehicles Observed • 48% Overall Safety Belt Usage • The Overall Safety Belt Usage Rate was weighted by the estimated truck VMT • 1.4% Standard Error • National and Major Regional Fleets: 55% Safety Belt Use • Independent or Local Fleets: 44% Safety Belt Use

WSU’s 2006 CMV Safety Belt Use Study • Determine CMV Driver and Passenger Safety Belt Use • Direct Observational Surveys • Safety Belt Use and Misuse • Geographic Characteristics • Demographic Characteristics

Sample Size • Followed NHTSA Criteria for Passenger Vehicle Safety Belt Observations • 32-county sample representing 86.86% of Michigan’s population • 3 additional counties representing the UP were also added to the sample

County Partitioning • Counties Partitioned into 5 Strata Based upon Previous Safety Belt Criteria, Total Vehicle Miles of Travel as well as Commercial Vehicle Miles of Travel (CVMT) • Number of Observations per Strata Based upon % of CVMT

Study Locations • Locations Randomly Selected • Freeway Exit/Entrance Ramps • Truck Stops • Truck Parking Lots • Rest Areas • Signalized Intersections • Weigh Stations avoided due to Police/ Weigh Master Presence

Observational Surveys • 50-minute Survey Period • 5 Vehicle Observational Target at Signalized Intersections • 10 Vehicle Observational Target at Other Locations • Overall Target of 1,720 CMV Safety Belt Observations

Observer Training • One-Day Training Course on Safety Belt Observations Conducted at WSU-TRG Facilities • 5-Day Field Data Collection Training on CMV Safety Belt Observations • QA/QC, Repeatability and Reliability Study

Data Collection • Timelines • March 6 through April 15, 2006 • Sunday through Saturday • 7 am through 7 pm • Equal Probability of being included in the sample

Vehicle Data Collected Vehicle Type Ownership Range Type of Cargo Carrier Name License Plate, State of Registration Driver and Passenger Data Collected Safety Belt Use and Misuse Gender Age Ethnicity Data Collection

Data Collection • 181 Locations Observed • 2,528 CMV’s Observed • 2,644 Drivers and Passengers Observed • 21 Locations did not have CMV Traffic at the Time of Observation • Alternate Locations were utilized

Findings of Observational Survey • Overall Weighted Safety Belt Use was calculated by summing the product of the stratum safety belt use rate and the stratum weight by the sum of the strata weights • Each stratum weight was determined by dividing the estimate CVMT in the stratum by the highest estimated CVMT for all the strata • The 95 percent confidence band were calculated by multiplying 1.96 by the square root of the variance • The standard error was equal to the square root of the variance • The relative error was calculated by dividing the standard error by the weighted overall safety belt use rate

Findings of Observational Survey • CMV Safety Belt Use Rates by Type of Vehicle

Findings of Observational Survey • CMV Safety Belt Use Rates by Type of Ownership, Range and Cargo Range of Vehicle Type of Cargo Type of Ownership

Conclusions • Michigan appears to have exceeded the national average for CMV Safety Belt Use • Michigan: 73.6%, 2006 Study • National: 48%, 2003 Study • Targeted Programs should be aimed at local fleets, dump trucks and construction vehicles

CMV Studies: Crash Causation and Safety Belt Use