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9 becomes a defect. As an example: Inspection reports repeat- edly showed clips missing in the station platform areas. The inspector or other maintenance worker would simply install another clip in place of the one that was missing. However, as the supervisor noticed this same issue on the reports regu- larly, he wanted to know why the clips were breaking in that area. During his investigation, it was found that the people cleaning the stations were washing the water into the track. The cleaning agent being used was highly corrosive, and when it came into contact with the negative return from the third rail, it caused the clips to corrode and snap. The cleaning personnel now use a non-corrosive cleaning agent and try not to wash the water into the track way; but had each broken clip not been recorded, this problem might not had been solved. The maintenance standards of this agency are very strict, as can be seen in the Maintenance Criteria table in Appendix E, Agency A. The gage tolerances are unforgiving: a minimum of ¹â8-inch tight and ¾-inch wide gage throughout the classes of track. The same tolerance applies to a 10 mph train as to a 60 mph train. Only ½ inch is permitted on alignment in any 62 feet of tangent track. These tight tolerances are relatively easy to maintain on DF track, but very difficult to maintain on tangent ballasted track. There are no criteria for high water levels because there are no tunnels in this third- rail powered system. Cross level tolerances are one-third that of APTA Safety Standards. This agency requires many more (20%â40%) good ties or fasteners than the APTA standard, mandating a good tie within 12 inches of a rail joint while APTA and FRA only require 24 inches. The only mainte- nance criterion that is the same as APTA and FRA is tread mismatch. Guard check and guard face gages are the same in all classes of track. The wear criteria are very strict also. The agency inspects its third-rail system annually and spec- ifies a maximum wear permitted on the third rail before it must be replaced. CASE EXAMPLE #2 This heavy rail transit system is in the very large category. It is more than 100 years old, and is also a third-rail system. The maximum speed is 55 mph. Fifty percent of the track is wood tie block encased in concrete, 30% is ballasted track, and 20% is elevated track. Approximately half the track is above ground and the other half below. The agency employs more than 100 maintenance workers, and follows its own mainte- This chapter presents detailed information from three heavy and one light rail transit agencies in the United States. Proac- tive maintenance appears to be the key factor in extending the life of any system, while deferred maintenance and lack of maintenance standards universally affect the longevity of the transits assets. Regular documentation, as shown in Case Example #1, has also proved beneficial in preserving the life of the system. Training and understanding of the criteria are also important components. Most effective is the develop- ment of a set of maintenance standards that are stricter than the published safety standards. CASE EXAMPLE #1 This transit agency is in the average-sized category, mean- ing it has between 11 and 50 miles of track. The propulsion system is third-rail and speeds exceed 60 mph. This sys- tem is close to 30 years old, and most of its track is DF. It employs more than 100 maintenance workers. This system uses APTA standards as its minimum requirements and has a written maintenance manual whose regulations are even more stringent; the agency plans to update its maintenance standards again. The agency inspects its track twice a week; runs a geometry car three times a year; and tests for internal rail defects twice a year. This transit agency also requires periodic training on APTA standards and CWR for their inspectors, supervisors, and key maintenance personnel. In discussions with personnel involved in maintaining this system, it was immediately apparent that they care about their system and have a sense of protecting the passengers. The maintenance supervisor was involved in the original construc- tion, so he has intimate knowledge of the system and how it was built. Inspection personnel are well-trained and knowl- edgeable in all aspects of the track structure, and are constantly walking track and reporting any defects, whether violations or not. One inspector walking track was seen to write down all observations, no matter how apparently insignificant. As the system nears the 30-year mark, unusual wear patterns have been observed on the rail, which may be the result of flaws in the original design and/or not enough super-elevation; as well as what appears to be premature decay of wood timbers encased in concrete. The track supervisor is quick to react and has taken advantage of new technology to make the repairs. The supervisor tracks inspection information to determine if a pattern of damage is forming, so he can stop it before it chapter three CASE EXAMPLES
10 nance standards. It has a safety priority system that restricts train speed. Track inspectors only file reports if there is a defect. A walking inspection is performed twice weekly. The agency runs a geometry car three times a year and performs rail integrity testing six times a year in the subway and three times a year on track outside. It has a formal track inspection training program with a written proficiency test. The mainte- nance workers are represented by a trade union. In the 1980s this agency was suffering at least one derail- ment per month and the track structure was rapidly crum- bling. In the early 1980s there was a derailment. There were no fatalities but there were significant injuries, and the NTSB was called in to investigate. This event spurred a massive recon- struction effort that lasted into the 1990s. This system is now in a state of good repair and the track is well maintained. In general, the agencyâs maintenance criteria appear to be one-third stricter than APTA or FRA minimum standards. It has a speed-based system that allows it to apply a slow speed order if a defect is observed, assuming it is not more than the slowest speed. The runoff criteria (Appendix F, item 5) are at the limit applied by APTA/FRA, which could be the result of its long cars. Item 8 (deviation from zero cross level) is the same as APTA/FRA minimum safety requirements. The required minimum number of non-defective ties in 39 feet is the same as APTA; however, the criteria for number of ties in a row are stricter. (FRA does not address ties in a row.) In reference to item 23, this agency does not permit the use of a torch, no matter what class track. Tread mismatch and gage face wear standards are basically the same as APTA/FRA. Restraining rail flangeways (item 27) have minimum and max- imum specifications, not just a minimum. This is important for prevention of rail wear and derailments. This agency identifies rail and third-rail wear limits. Minor defects are repaired immediately and inspectors carry a tool with them when walking track, as well as a small backpack with miscellaneous small parts and a couple of mechanicsâ tools. Many carry a small tool bag. This supervi- sor says the transit agency has come a long way with hard work and the dedication of employees who remember the debacle of the 1980s; the challenge is to pass this philosophy onto the next generation. CASE EXAMPLE #3 This is a large heavy rail system (101â200 miles). It is just over 30 years old and reaches speeds greater than 60 mph. The propulsion system is third-rail. The majority of track is DF (70%) and the rest is ballasted track (30%). The agency uses both APTA and FRA maintenance standards and employs between 51 and 100 maintenance workers who inspect their track once a week and run a geometry car twice a year. None of its track is governed by the FRA. The agency reviews and revises its standards annually. Most of its system is below ground. This system and many others built 30 or more years ago suffer from stray current, which was not understood as it is today. Stray current occurs when there is an interruption of the return path to the sub-station. When the return path (negative return) is interrupted or when the rail is grounded, stray current is produced and becomes very corrosive. The older fasteners were not constructed as they are today; therefore, if stray current is not addressed, it accelerates the corrosion of the reinforcing steel, bolts, and even the rail. This transit agencyâs maintenance activities are intensely focused on keep- ing stray current at bay. In most cases the agency follows APTA Safety Standards. Its maintenance criteria for surface deviation are the same as APTA. Cross level is also the same as APTA. Tie restric- tions, with respect to number in a row, match those in APTA. Maintenance criteria for ties at a joint, torch cutting, tread and gage mismatch, rail end batter, flangeways, and frog tread wear all match the minimum track safety standards outlined by both APTA and FRA. The only requirements that are stricter are guard check and guard face gages, which are within 15% of APTA. CASE EXAMPLE #4 This light rail system is above average in size and uses cat- enary as a propulsion method. It is approaching the 30-year mark in age. Maximum speed is 45 mph. It has embedded track (18%), DF track (22%), and ballasted track (60%). It employs between 51 and 100 maintenance workers, uses APTA minimum track safety standards, and, in most cases, APTA maintenance standards. It inspects its track twice a month and its turnouts once a month. Geometry and rail flaw detector cars run once a year. None of its track is governed by the FRA. It does not have a CWR plan. It does not have a for- mal training program for signal maintainers or track inspec- tors; the only required training is for equipment operators. Gage requirements (item 1) are slightly stricter than APTA. It has no criteria for variation in alignment in tangent track. Its criterion for surface deviation in 31 feet (item 7) is much stricter (70% more) than the APTA Track Safety Standards. All criteria for warp, ties, torch, tread and gage mismatch, restraining rail, flangeways, and frog wear are consistent with APTA. Guard check and guard face are twice and three times as strict as APTA, respectively.
