The importance of and need for the underwater investi gation of railroad bridges cannot be overstated, espe cially in light of the significant age of so many railroad bridges and the trend of late towards severe storms, greater-than-ever high water conditions and the po tential for scour to levels that have never previously been experienced. In addition, railroad bridges, more often than not, have larger, more closely spaced foundations that make them particularly more vulnerable to scour and other water way effects, which are by far, the leading cause of bridge fail ures from an underwater standpoint. Given these realities, it's easy to see why it is so important that the properly executed underwater inspection of railroad bridges should be imple mented as part of an effective bridge maintenance program, as well as to identify any critical conditions looming out there before it is too late. Furthermore, the Bridge Safety Standards (49 CFR Parts 213 and 237) issued by the Federal Railroad Administration in 2010 indicates that as part of a railroad's bridge maintenance program, underwater assessments should be conducted, either by diving or other appropriate means, in order to establish and monitor the condition of substruc ture units subject to scour and other below water concerns. In this regard, there are various underwater technologies that can be used to supplement and augment conventional under water inspection by properly trained divers, -which includes at times, -when diving itself can not be safely accomplished, to adequately assess existing conditions and identify any poten tial problems before they manifest themselves.
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