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42 Hazardous Materials Transportation Incident Data for Root Cause Analysis
Table 4-6. Proportion of cargo body type in
MCMIS coded correctly, based on
comparison with TIFA data.
Cargo Body Type Frequency % Correct
No cargo body (e.g., bobtail) 251 49.0
Van 5,432 71.9
Flatbed 1,713 70.1
Tank 1,011 77.7
Auto carrier 77 68.8
Dump 1,947 65.5
Refuse 288 64.9
cargo body types from the TIFA file, the number of such body types in TIFA, and the percentage
identified correctly in MCMIS.
Table 4-7 makes a similar comparison for truck configuration. The primary truck types,
straight trucks with no trailer and tractor-semitrailers, are identified accurately 87.5% and 75.5%
of the time, respectively. Less recognizable types like straight trucks pulling a trailer or bobtail
tractors are less often accurately identified in MCMIS.
Finally, Table 4-8 shows the percentage of selected variables that are coded the same in TIFA
and the MCMIS Crash file. Variables shown in Table 4-8 are drawn from the FARS file and not
from the TIFA interview. GVWR class in MCMIS aggregates the classes to 1 to 2, 3 to 6, and 7 to 8.
The variable is left unknown in 62% of the cases, so the last row of the table shows the accuracy
of the variable in MCMIS excluding unknowns.
4.1.12 Quality Control Process
The MCMIS reporting methodology presents a difficult quality control process. First, there
are a large number of jurisdictions filling out PARs that vary from state to state. Although many
reporting agencies do not break down the reporting to the officer's level by providing a badge
number, the 151,000 reports filed in 2005 were filled out by more than 61,000 agencies or indi-
vidual officers. This means that, on average, a police officer from a specific agency might fill out
less than three truck PARs in a given year. Assuming there are about 3,000 placarded shipments
involved in crashes each year, the probability that a police officer will have to fill out a PAR for
a placarded truck is on average, less than once every 20 years (60,000/3,000). This poses a signif-
icant training problem if the officer will be filling out the hazmat supplement only a few times
in his or her career. Requiring or sponsoring a formal training program in 50 states for an event
that occurs a few times in an officer's career is probably not cost effective. Providing a guide to
Table 4-7. Proportion of truck configuration
in MCMIS coded correctly, based on
comparison with TIFA data.
Truck Configuration Frequency % Correct
Straight truck 2,839 87.5
Straight truck plus trailer 373 42.9
Other straight truck 8 75.0
Bobtail tractor 175 61.7
Tractor-semitrailer 7,956 75.5
Tractor doubles 439 76.1
