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Database Analysis 89 at the stop line. The FRA report has only one parameter, limited sight distance. Based on the def- inition in the FRA reporting guide (FRA 2003), the view as the driver approaches the crossing, the first NTSB parameter, should be reported in the FRA database. The two assessments agreed in 27 cases, less than half the 57 for which a comparison was possible. In 22 of these cases, both assessments agreed that there were no obstructions. In one of five remaining cases, the obstruc- tion was a passing train, a factor not considered to be an obstruction by NTSB. In the four remaining cases, both recorded that an obstruction to the driver's vision was present on approach. That leaves 30 cases where the two assessments disagree. In five of the cases, the NTSB investigators concluded that the driver's view was obstructed both on approach and at the stop line--at the stop line for one case, and for the remaining four on approach. It seems clear that the NTSB investigators and the employees filling out the FRA grade-crossing report differ on the definition of what constitutes an obstruction as a driver approaches the grade crossing. Given that the NTSB investigator visited the scene, the NTSB assessment is thought to be a more accu- rate assessment. Differences also were observed in the types of signage at the grade crossings. In 10 of the 57 cases, the FRA database stated that no stop sign was present whereas the NTSB report stated one was present. In 4 of the 57 cases, the FRA database shows there was a stop sign when the NTSB investigator reported none was present. Being inaccurate in 25% of the cases makes it dif- ficult to draw conclusions regarding the effectiveness of stop signs at passive grade crossings. Because the NTSB investigators take statements from witnesses and observe the conditions at the accident scene at the time of the accident, they clearly have an advantage regarding reporting accuracy. There were cases where the NTSB reported a building, a large pile of rocks, overgrown vegetation, and cars on the tracks as blocking the vision of vehicles approaching the crossing. Clearly, conditions change at grade crossings and if there is no way to capture those changes in the data being used by the railroad employee filling out the FRA grade-crossing report, the FRA report will always be less accurate. 4.8.5 Probable Cause Findings The NTSB (1998) report recognizes that determining the probable and contributing causes of passive grade-crossing accidents is a challenging task. It is even more difficult to summarize the findings based on only 60 cases. The following discussion summarizes the findings, recognizing that no finding is likely to be statistically significant. There were 14 incidents at private grade crossings and 46 at public crossings. In 33 of the 60 cases, more than one-half, limited sight distance was listed as the primary cause. In 28% of the private crossing incidents, there was limited sight distance, while 63% of the public crossing incidents cited this as a factor. Stop signs were present at 3 of the 4 private grade-crossing incidents with limited site distance and at 15 of the 29 public grade-crossing incidents with limited sight distance. Since one of the rec- ommendations of an earlier NTSB report was that stop signs be installed at all passive grade cross- ings, it is interesting to note that stop signs were present at one-half of the private crossings and about one-third of the public crossings. Regarding the primary cause of these accidents at cross- ings with stop signs, the driver ran the stop sign in 3 of the 7 incidents at passive grade crossings (about half) and 13 of the 15 public grade crossings with stop signs (almost 90%). Clearly the rec- ommendation to place stop signs at all grade crossings with limited sight distances will have lim- ited effect until the compliance rate with the stop signs is improved. Regarding injuries and fatalities, there were two cases where a person on the train was injured. Two crew members and 12 passengers were injured in these accidents, respectively. Fatalities or