CMV Studies: Crash Causation and Safety Belt Use

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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

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Crash Statistics in Michigan
Source www.michigantrafficcrashfacts. org
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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)
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CMV Fatalities

• 5,000 Average Fatalities per Year involving
  Commercial Motor Vehicles (CMVS) 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

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WSUs 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

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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

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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

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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

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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

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WSUs 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

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Sample Size

• Followed NHTSA Criteria for Passenger Vehicle
  Safety Belt Observations
• 32-county sample representing 86.86 of
  Michigans population
• 3 additional counties representing the UP were
  also added to the sample

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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

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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

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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

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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

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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

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Data Collection

• 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

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Data Collection

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

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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

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Findings of Observational Survey

• CMV Safety Belt Use Rates by Type of Vehicle

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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
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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