| The U.S. Navy, the U.S. Army, and public and private local railroad companies own and operate nearly 25000 miles of railroad track. Although traffic is generally low volume and low speed, this track serves a vital transportation niche. A technological gap existed, however, in that a simple method was not available for routine condition assessment which is necessary for an overall track management program.;This thesis developed a simple method. A Track Structure Condition Index (TSCI) was created that reflects a track's physical ability to support military, short line, or industrial traffic and the maintenance, repair, or rehabilitation needs to sustain that traffic. The basis for TSCI development was to combine all pertinent track components into three major groups (rail and joints, ties, and ballast and subgrade) and developing condition indices for each. These component group indices are the Rail and Joints Condition Index (RJCI), the Tie Condition Index (TCI), and the Ballast and Subgrade Condition Index (BSCI).;Rating data were collected using the direct rating approach from a panel of track experts. An interval rating scale, ranging from 0 to 100, formed the basis for the ratings. A rating of 100 implies an absence of observable distress. Different intervals on the scale relate to different degrees of deterioration, operational impairments, and work needs on the track. A weighted deduct-density model was used to transform the rating information into the desired condition indices. Twenty-four distinct distress types evolved from the research for use in the model. Different severity levels for those distress types were also established. Those levels were related to possible operational restrictions placed on the track and the urgency for maintenance and repair. Inspection procedures were also developed.;Field verification confirmed that the inspection process, which incorporates sampling techniques, was simple and relatively quick to accomplish. The computed indices correlated extremely well to average panel ratings.;This thesis also describes potential uses for these indices and provides an example of use. |
