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Database Analysis 93 Table 4-29. Sampled crashes by hazmat group. Hazmat Analyzed Crashes Estimated 2002 Totals Description Group Crashes Spills Crashes Spills 1.1 1.6 Explosives 19 2 21 2 2.1 Flammable gases 148 14 256 21 2.2 Non-flammable gases 60 8 102 12 2.3 Gaseous poisons 11 1 18 2 3.0 Flammable liquids 544 125 914 182 4.1 4.3 Flammable and reactive solids 7 2 8 2 5.1 5.2 Oxidizing materials 31 9 36 10 6.1 6.2 Poisonous and infectious substances 14 2 16 2 7.0 Radioactive materials 4 2 4 2 8.0 Corrosive liquids 75 16 139 23 9.0 Miscellaneous hazardous materials 57 23 86 27 Unknown Hazmat group could not be determined 17 5 28 9 A similar process was used to input PAR data. As the information was being filled in from the PAR, the data entry form showed the default values for any parameters that were previously entered based on information supplied by MCMIS and HMIRS. Any inconsistencies were changed to reflect the information contained in the PAR. Frequently, the changes were not inconsistencies, but expansions of the data. For example, many PARs list the actual GVW of the vehicle and, in those cases, that number was input in place of a broad weight category. The final step in populating the Hazmat Accident Database involved entering information that was obtained through direct telephone conversations with the involved carrier. These calls verified the accuracy of the entered information and provided specific information only the carrier could supply. This included such information as the amount of material being shipped; whether there was a spill and, if so, how much; the manufacturer and specification number of the packaging; and the year the packaging was fabricated. Valuable information on packaging characteristics was obtained from carriers who provided the DOT specification number for the tank, the year it was manufactured, the manufacturer, type of rollover protection on the cargo tank, and the inspection history. Many carriers could estimate the amount of material being shipped and if any was spilled. The type of damage to the cargo tank could sometimes be recalled, usually only if there was a spill. Most carriers also were willing to provide information on the driver's experience. 4.9.5 Quality Control Checks Several quality control checks were built into the data collection process. Accuracy checks were performed at three critical junctures: (1) after the data from the PAR were entered for the crash, (2) after the carrier calls were completed, and (3) whenever a reviewer changed a pre-existing database entry. Special efforts also were made to identify and reconcile blank fields. In addition, error-trapping queries were run to identify reporting inconsistencies (e.g., Interstate highways that were not flagged as limited/controlled access). Finally, summary reports were generated of each recorded crash to use in reviewing the entered information or to use as a reference during carrier correspondence. 4.9.6 Database Enhancements and Limitations The fields in the Hazmat Accident Database reflect a list of parameters that are considered pertinent for safety analysis. While every effort was made to obtain relevant information, it was not expected that it would be possible to populate all of the fields. Nevertheless, significant