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

All Crashes in Michigan

424,852373,028

80,922 80,567 76,598 73,118 66,729

415,675400,813 395,515 391,485

350,838

87,820 87,043

0

100,000

200,000

300,000

400,000

500,000

1999 2000 2001 2002 2003 2004 2005

Cra

sh

Fre

qu

en

cy

(C

ras

he

s/Y

ea

r)

Total

Injury

1,249 1,237 1,206 1,175 1,172 1,055 1,030

0500

1,0001,500

1999 2000 2001 2002 2003 2004 2005

Trend of Truck-Related Crashes in Michigan

18,281

4,136 4,001 3,206 3,260 3,182 3,209 2,957

16,23817,37617,16617,476

20,81221,665

0

5,000

10,000

15,000

20,000

25,000

1999 2000 2001 2002 2003 2004 2005

Cra

sh F

req

uen

cy

(Cra

shes

/Yea

r)

Total

Injury

152134 137

117132 122

163

0

50

100

150

200

1999 2000 2001 2002 2003 2004 2005

Crash Statistic

s in Michiga

n

Source: www.michigantrafficcrashfa

cts. org

Source: www.michigan.gov/mdot (Total VMT for 1999-2005 and CVMT for 2001 and 2005)

Vehicle Miles of Travel in Michigan

93.1 94.9 96.4 98.2 100.2 101.8 103.2

4.5 4.8 5.2 5.5 5.9 6.4 6.8

0

20

40

60

80

100

120

1999 2000 2001 2002 2003 2004 2005

VM

T (

in B

illio

ns

)

Total VMT

CVMT*

*CVMT was assumed to maintain a 7.23% growth rate per year

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

Tru

ck C

rash

es (

%)

0

10

20

30

40

50

60

Causal Factors of Multi-Vehicle Car-Truck Crashes

70

80

90

100

Driver Vehicle

10%

Environment Other/Unknown

54%

74%

76%

39%

3%6%

18%

8%

4%

8%

0%

AUTHOR LEGEND

Gou (analysis of 214 crashes) Toth, (analysis of 159 crashes) Blower, Craft, 2003 (analysis of 100 crashes)

AUTHOR LEGEND

Gou (analysis of 214 crashes) Toth, (analysis of 159 crashes) Blower, Craft, 2003 (analysis of 100 crashes)

Predominant Causal Factors

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

CMV Crash Causation

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 Use Study

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

2003 CMV Safety Belt Usage

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

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

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

69.6%

75.8%

73.4%74.8%

73.7%74.6%

68.5%

66.3%

60%62%64%66%68%70%72%74%76%78%

Nation

al F

leet

Regio

nal F

leet

Loca

l Fle

et

Indi

vidua

l Owne

rship

Inte

rsta

te

Intra

state

Non-H

azar

dous

Hazar

dous

% o

f S

afe

ty B

elt

Us

ag

e

Type of Ownership Range of Vehicle Type of Cargo

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