Center Truck Performance on Low-Floor Light Rail Vehicles (2006)

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

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

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