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OCR for page 87
Database Analysis 87 4.8.2 Approach to Identifying Root Causes The approach taken in all NTSB investigations is similar, although the scope of the individual pieces may vary. In all cases, a team of NTSB accident investigators is dispatched rapidly to the scene of the accident to collect evidence that might be usable in determining contributing causes. The evidence collected includes data describing the accident scene, the amount of damage to equipment, and the extent of injuries to individuals involved in the accident. Witness statements are always collected and it is pointed out in several investigations that it is important to get those statements quickly because witness memories fade. The NTSB then goes through an extensive analysis of the collected data and will frequently follow up with requests for additional informa- tion as the analysis proceeds. By going to the scene, the NTSB has all the contact information needed for follow-up purposes. The NTSB investigator collects the following information: Location, Date and time, Lighting conditions, Type of motor vehicle (year and type), Train action reported (horn sounded/auxiliary lights on), Signs present (crossbuck, advance warning, and/or stop sign), Physical characteristics (limited sight distance, angle of intersection, road or track curve, and presence of a nearby road intersection), and Number of injuries and fatalities. All of these items, except some of the physical characteristics, are included in the grade-crossing incident report submitted to FRA. The FRA accident database does not document the proximity of the grade crossing to other roads nor does it document whether the road or track is curved. The curvature of the road or rail track was not listed as a probable or contributing cause in any of the 60 cases (NTSB 1998), and there was only one case where the presence of traffic plus a nearby intersection was listed as a contributing cause. Thus, the absence of this information being cap- tured in the FRA database is not considered to be a significant weakness. Whereas the NTSB find- ings are based on a site visit and witness statement, FRA does not require either of these. While there are narrative fields provided in the database, during the time period of the NTSB study, the narrative fields were left blank for all grade-crossing accidents for both active and passive grade crossings--more than 3,000 reports. The analysis performed here included an additional task that was not performed by NTSB-- a comparison of the data reported to FRA and the data reported by NTSB for the same accident. Although reports for all 60 of the accidents were found, the matching task, initially thought to be easy, turned out to be a challenge for the following reasons: NTSB did not include the FRA incident number, so it had to be discovered. NTSB listed the closest town to the grade crossing whereas FRA reports the nearest timetable station, county, and city (if the accident occurred within city boundaries). For almost one-third of the cases for which matches could be found, it was necessary to refer to a map to find the location of the grade crossing, a time-consuming process. If both databases had provided the GPS coordinates (an option in the rail equipment accident database), then the month, day, and GPS coordinates would have made it much easier to match the accidents in the two databases.