The reinforcing plate of the collision posts is attached to the underframe by welds of the type cited in the American Welding Society Handbook. A sound weld was not obtained in this case. The impact of a collision can subject these welds to severe bending stresses, as well as impact loading, both of which are warned against. The calculations assumed joint penetration to the full ½ inch depth of chamfering, although this is not supported by the handbook.
It appears that the reduced bevel of the attachment plate and the use of a single-bevel welds from one side were features of the method employed in welding the collision post attachment plate to the underframe in many of the Highliner cars. The Board has examined samples of welds taken from another Highliner car and found the smaller bevel in one of two welds.
In summary, because of the design of the attachment weld, incomplete fusion in the welding process and a reduced cross section of weld are likely to be present in other cars. Further, the assumptions as to the strength of the weld, even if properly fused, could not be fulfilled by the bevel actually used in construction. The added weld did not solve either the reduced dimension of the bevel or the poor fusion. The assumption that the original design weld would be fully effective does not appear justified, since competent welding manuals have warned against the single bevel weld in joints subject to bending or impact conditions.
The effect of these shortcomings in terms of fatalities and injuries in this accident has not been determined. This crash also involved a mismatch between the physical features of the older and newer cars, and the collision posts might have carried away, even if at full strength. However, there should be assurance that all collision posts meet current FRA requirements, which are at present the only defined form of crash protection. This assurance probably cannot be provided by visual inspection because the original design assumptions were deficient. However, it appears that retrofitted changes such as the addition of welded reinforcement could assure that the requirements are met.
The Safety Board has not determined whether compliance with current Federal regulations would have provided strength sufficient to resist this crash. The analysis of the evidence in that regard and any resulting recommendations will be included in the Board's final report.
The problem of the inadequately attached collision posts does not imply that the cars are unsafe to be operated in the sense that a crash would be caused. It does, however, imply that crash resistance of many collision posts would be found substantially below that intended to be provided by
