Click for next page ( 70


The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 69
69 APPENDIX E Track Maintenance Standards A comparison was made between a maintenance stan- The light rail operator in Karlsruhe generally uses the strat- dard issued by a long-established transit system and the egy of "advanced maintenance," which is linked to the avail- standards used in Germany. The purpose was to discover if able budget. When sufficient funds are available, a "wear LFLRVs are being operated in a different maintenance con- reserve" will be built up, which allows operation with reduced text in Europe than in the United States. It was found that maintenance, using up this reserve, for some years (e.g., 3 to requirements of the U.S. document did not contrast signif- 5 years) on most lines, should a need arise. icantly with German regulations in most areas. The U.S. In general, no other set of standards is used for operating maintenance standard was compared with both the Ger- LFLRVs in comparison with standard, high-floor vehicles. man maintenance requirements for light rail (BOStrab) There is one exception in that additional measures have to be and short-line railways (NE-Bahnen) because the U.S. stan- taken to ensure safe entry and exit situations at platforms (i.e., dard studied had characteristics of both heavy and light rail fixing the track against the platform to ensure a minimal gap). systems in some sections. The comparison was based on experience in Karlsruhe with the maintenance of light rail Fault and Reaction Values infrastructure and included discussions with the Karlsruhe Transit system. The U.S. procedure consists of identifying different stages Approval of railway infrastructure and rolling stock in (GREEN, YELLOW, and RED) during maintenance inspec- Germany is carried out by the representative for light rail tions and then stating what specific measures are to be safety (Technische Aufsichtsbehrde), which is the responsi- undertaken when specific measurements exceed appropri- ble supervisory authority in each state. The transit systems ate limit values. These measures were compared with the are responsible for everyday operations and maintenance German requirements. The regulations were seen to be very and one person, the so-called "chief operating superin- demanding in terms of short response times (e.g., with RED tendent" (Betriebsleiter) is personally responsible for safe meaning a reduction of the speed limit to 10 km/h and operations. The technical authorities will, however, inspect defect removal within 72 hours). This means that it may be the transit system at regular intervals (typically yearly). difficult to organize the work needed within the time avail- Furthermore, there are some special compulsory inspec- able in terms of setting up the site, operational measures tions by the authorities (e.g., inspection of structures every during the construction period, organizing subcontractors, 3 years). and so forth. Work is required on the track at the YELLOW Even though there are numerous legal requirements, the stage as well. management of each Transit system and especially the "chief Early detection is practiced in Germany. According to the operating superintendent" (Betriebsleiter) has substantial "BOStrab" (tramway) regulations, every German Light Rail freedom as to how and when maintenance is carried out Transit system has to develop a table (Quermatabelle), within the legal limits. This becomes apparent when looking which includes all values relevant to track guidance (e.g., at the maintenance levels throughout different German sys- wheel back to back distance), covering vehicles, and track tems. In general, it is the German philosophy not to work to gauge and track geometry, including switches and crossings. the maximum wear limit but to have shorter maintenance This table includes minimum and maximum values outside intervals to ensure problem-free operations and high running of which safe operations would be jeopardized. The respon- comfort and also to save cost. sible "chief operating superintendent" (Betriebsleiter), or an

OCR for page 69
70 engineer appointed by him, determines the necessary meas- reports issued by the operators in Germany is considered to ures to ensure the track always remains within these values. be of value. This table is generally prepared by external experts (typi- cally the firms that design track, switches, crossings, and other infrastructure) and updated when necessary to ensure track Specific Standards and wheel wear are minimized. It must be updated where The following standard applies to the ballast roadbed in there is a potential new safety risk, for example because of the Germany for light and heavy rail (but not high speed heavy rail) introduction of new types of vehicles or the use of different wheel profiles. Ballast ahead of crosstie: 40 cm (15.7 inches) Heavy rail values exist which are valid all over Germany, Layer thickness under crosstie: 30 cm (12 inches) but light rail values vary. This is because wheel/rail guidance Sub-Ballast: 20 cm (7.9 inches) geometry differs from light rail system to light rail system. However, many light rail systems use the heavy rail values as The ballast material specified for the U.S. transit system guidance. was 3/4 to 11/2 inches (18 mm to 38 mm), which is smaller than The analysis showed that the U.S. standards are actually the size required in Germany of 22 mm to 63 mm (7/8 to 21/2 more demanding in terms of quicker response times. inches). The smaller size of ballast may not take up track forces as well. Although the structure of the ballast was simi- Inspections lar, the U.S. system did not require as substantial a shoulder, which may provide reduced stability. In Germany, the responsibility for service reliability lies In Germany, gauge is defined as the minimum distance with the responsible track maintenance engineer and/or the between the rails measured 14 mm (0.55 inches) and for some "chief operating superintendent" (Betriebsleiter). This per- rail types 10 mm (0.4 inches) below the top of the rail. In the son's qualifications, in addition to a technical or engineering United States, the gauge is measured at 5/8 inch (16 mm) or 3/8 degree, include specialized training of about 290 hours of inch (9.5 mm) in equivalent situations. The U.S. standards for experience. Table E-1 compares the inspection intervals used gauge are similar to those used in Germany for both tangent in Germany with those of the U.S. transit system. track and sharper curves. In Germany, switches are examined more frequently than The U.S. standards for horizontal track alignment and for required in the U.S. standard. In contrast, in the United curves, superelevation, and corresponding speed limits, were States, there are more on foot inspections of the track than found to be very much the same as those used in Germany. in Karlsruhe. Apart from these specified inspections, a fur- As Figures E-1 and E-2 show, the wear limits on rail are very ther important diagnostic is the use of the normal service similar too. vehicles travelling at maximum speed, in order to be able to estimate certain track bed errors (e.g., warping of the Top wear = 25 mm (1 inch), side wear = 20 mm (13/16 inch) track). Detection of track defects while travelling at speeds up to 5 mph is unlikely to be as effective. Minor defects will In Germany, the guard check gauge dimension for heavy rail only be detected when "walking the track," while track bed is 1,394 mm (54.88 inches) for a 1,435 mm track gauge with errors can sometimes be better detected if travelling at grooved guardrail of 41 mm (1.6 inches). For tramways using maximum speed. The collection of regular track failure embedded rail, the guard check gauge is between 1,404 mm Table E-1. Inspection periods, USA and Germany. Inspection requirement USA Germany Section patrol - Frequency 3 times per week 3 times per year minimum (Note 1) - Method On foot or by vehicle at On foot and by scheduled speeds up to 5mph. trains or trams. Switch inspection Once per month. Visual inspection and grease once per week. 6 inspections per year. 1 geometric inspection per year. Note 1: Further inspections may occur if operators report faults.

OCR for page 69
71 Figure E-1. U.S. maintenance document. Figure E-2. German standard. and 1,413 mm (55.28 inches and 55.63 inches). This is a rea- wheels and narrow flanges. The U.S. requirement did not sonably exact match with the U.S. requirement that was make this differentiation. studied (GREEN Maintenance threshold) of between 553/8 The number of defective ties allowed in a section is more (1,406 mm) and 555/8 (1,413 mm). However, for segregated than in Germany. The measurements of the crossties are track, Light Rail, the German standard says that the guard identical to those used in Germany. The allowed defective check gauge should be in the range >1402 mm to <1407 mm. crossties per section may be critical. This results in worse (>553/16 to <553/8 inches). This is to allow for independent track condition and/or increased maintenance cost.