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Database Analysis 47 4.2.1 Database Description Prior to 2005, the HMIRS database consisted of three tables. The CON Table provided informa- tion on the incident. the MAT Table contained the name and address of the shipper, origin and des- tination address, the hazardous material being shipped, the amount released, and any damage to the packaging. The RMK Table was used for remarks. In most cases, there is one MAT entry for every CON entry. The RMK Table limits the text field to 80 characters, a legacy from the 80-character entry on an IBM card. Thus, there are often several RMK entries for each CON entry. Beginning in 2005, the HMIRS database was significantly restructured. The new database structure is shown in Figure 4-2. Figure 4-2 shows that all of the tables are related to the IREPORT Table. This table assigns a unique report number to each carrier-reported hazmat incident. IREPORT contains information on the carrier, the incident location, and impacts in terms of fatalities, injuries, and economic dam- age. It also provides contact information so that PHMSA data entry personnel can request additional data when certain fields are left blank. The IEVENT Table performs a function similar to the old RMK Table. The big difference is that after 2005, each line defines part of the event sequence. Although most IRECORDS have only one IEVENT record, about 10% have four IEVENT records. In 2005 and 2006, there were no IREPORT entries that had more than four IEVENT records. The IACTION Table was new in 2005 and gives the carrier the opportunity to identify changes that have been made to its operations as a result of the incident. An examination of the action statements demonstrates that some carriers have prepared thorough accident investigations and probably know the contributing causes and root causes of the incident. This table provides a way of identifying improvements that have been made without providing evidence of negligence that could be used in any litigation arising as a result of the incident, which is a major concern to the accident reporter. Figure 4-2. Relationship among HMIRS tables from 2005 onward.
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48 Hazardous Materials Transportation Incident Data for Root Cause Analysis Table 4-10. Total number of incidents reported by phase and mode, 2005 and 2006. T_PHASE Air Truck Rail Water En Route 1,049 4,871 1,303 83 Loading 553 4,542 30 6 Unloading 595 19,487 70 24 En Route Storage 1,868 1,709 46 24 The SHIPPER Table provides a listing of the shippers with hazardous materials involved in the incident. If the shipment was not "exclusive use," there could be several SHIPPER records for each IREPORT record. Similarly, a shipper could put more than one MATERIAL in the shipment, meaning that if an incident occurs, there could be several MATERIAL records for each SHIPPER record. The restructured database provides the opportunity to identify individual packages of the same material by having multiple PACKAGE records entered for a single MAT_ID record in the MATERIAL Table. Lastly, it is possible to describe where, how, and why each of the individual packages failed in the PKGFAIL Table. If there are multiple layers to the package, those can be described in the PKGLAYER Table. Since both the PKGLAYER and PKGFAIL Tables are related to the MATERIAL Table and not to each other, it is not possible to describe how the packaging layers failed in the incident. The post-2005 structure of the HMIRS database provides the opportunity to report the per- formance of individual packages in shipments carrying multiple packages of more than one kind of hazardous material from more than one shipper. Although this level of detail is not often needed or used when reporting an incident, the structure of the database permits it. In all other databases, when there are multiple classes of hazardous materials in the shipment, their struc- ture permits only one hazmat entry. The reporter must choose which hazardous material to des- ignate, and this can become a source of disagreement when the records in two different data- bases report that the vehicle contained different classes/divisions of hazardous materials. In actuality, both types of hazardous materials were present. The structure of the HMIRS database is ideally suited for examining package behavior in both the normal shipping environment and following an accident. Table 4-10 shows the total num- ber of incidents reported in 2005 and 2006 by mode and phase, and Table 4-11 shows the total number of accidents reported by mode and phase for the same two-year period. A comparison between the columns in Table 4-10 and Table 4-11 shows that all of the inci- dents reported for water and air are related to normal transport and are not related to accidents. Even with truck and rail, approximately 10% of the en route incidents are related to accidents. The focus of HMIRS is clearly not the transport accident environment. For the normal transport Table 4-11. Total number of accidents reported by phase and mode, 2005 and 2006. T_PHASE Truck Rail En Route 558 91 Loading 1 Unloading 13 En Route Storage 1 1