NST has been assisting mainline railroads in updating of construction drawings for many years. The reality is that not all drawings are completely marked, or correctly marked, when returned from the field installation. Therefore, the process of updating these drawings is much more than a simple CADD operation. In many cases, circuit changes and detailing are inconsistent, or major equipment has been changed with only a narrative and little if any circuitry provided. We will work with the appropriate people to resolve the problem as much as possible to maintain the integrity of this key documentation.