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24 to incidents resulting in injuries/fatalities, and less focused The NTD Database on reporting incidents that do not. For example, prior to the issue of the 2008 Safety and Security Reporting Manual, an The NTD contained 66 data fields for each major incident. incident could not be classified as a major incident if a fatality Table 5 shows the data fields in the NTD summarized by was the result of a suicide, or if there were less than two injuries category of data. requiring immediate medical attention away from the scene. As shown in Table 5, the data fields contained in the NTD Table 4 shows criteria previously considered indicative of a provide comprehensive information for a variety of data cate- major incident and the years they were included. gories. The date and time of each incident is clearly specified, The implications of these changes in incident reporting and includes a field to indicate the time zone of the location should be considered when analyzing the data contained in where the incident occurred. The location of the incident is also the NTD. For example, prior to 2003, rail collisions at a grade clearly identified, and users are even provided with the option crossing were subject to the same reporting criteria as all other of specifying the exact longitude and latitude of the incident incidents, while in 2003 the NTD made all rail collisions at a location. All parties involved in the collision are classified (i.e., grade crossing reportable. From 2004 to 2007, collisions at pedestrian, motor vehicle) and described. grade crossings were given their own specific criteria (i.e., prop- The key categories of data with regard to safety analysis are erty damage exceeding $7,500, or one or more injuries) to be consequence of the incident, alignment/crossing controls, used in evaluating whether or not they were reportable. In the environmental factors, and exposure to risk. The consequence most recent edition of the NTD Safety and Security Reporting of the incident is quantitatively defined by the number of Manual, rail collisions at an at-grade crossing are once again injuries, the number of fatalities, and the extent of property subject to the same reporting criteria as all other collisions, but damage (in dollars) resulting from the incident. The alignment these have been changed since pre-2003. It should also be noted is identified based on the classification of the right-of-way that the definition of a crossing can vary. For a while, some cities as exclusive, semi-exclusive, non-exclusive, etc. The crossing (such as San Francisco) only defined LRT crossings with gates control field indicates the presence or absence of passive or as crossings. active control devices for road/rail grade crossings. If the inci- Frequent changes in reporting standards result in some dent occurred at a street intersection (common for LRT), the confusion among local transit agencies as to which inci- control device at the intersection is also provided. Environ- dents are reportable from year to year, and lack of uniformity mental factors include illumination, weather, ROW condition in collision data between years results in reduced ability to (i.e., dry, wet, slush, etc.), ROW configuration (straight, curve, make inferences from available data. Despite these disadvan- uphill, downhill, etc.), and ROW type (i.e., divided highway, tages, the NTD has introduced changes to NTD reporting intersection/grade crossing, etc.). criteria as part of its effort to balance the need to maximize Although the NTD included data fields for measures of expo- the quality and relevance of safety data in the NTD while sure, all five data fields in this category were blank for all of the minimizing unnecessary data collection and reporting at recorded incidents. In addition, examination of the NTD Safety the local level. and Security Manuals between 2003 and 2008 indicated that the Table 4. Reportable criteria. Years Included in Major Reportable Criteria Incident Reporting Criteria (Inclusive) A collision at grade crossing 2003 A collision at grade crossing resulting in at least one injury requiring immediate medical attention away from the scene or property damage equal 20042007 to or exceeding $7,500 A collision with person(s) on a rail right-of-way (ROW) resulting in at least one injury requiring immediate medical attention away from the scene for at 20032007 least one person A mainline derailment 20032007 A collision involving a rail transit vehicle resulting in at least one injury requiring immediate medical attention away from the scene for at least one 20032007 person Forcible rape 20062007 Confirmed terrorist events 20062007