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62.1 Conceptual Development TCRP Report 2 (2) described the development and appli- cation of LFLRV technology in the United States and Canada; however, it was published in 1995 and much has happened in the intervening 10 years. The first modern low-floor streetcar was introduced into service in Geneva, Switzerland, in 1984. Sixty percent of the floor level was at 480 mm (19 inches) above rail. It was built by Duewag and ACM Vevey.Vehicles of this type are known as âpartial low floor.â Before this, the typ- ical streetcar or LRV had an even floor height sufficient to clear the wheels on all trucks. The partial low-floor concept was based on the fact that, if a significant proportion of the floor height was lowered, most users would benefit from eas- ier access, including those most likely to need it. The partial low-floor concept did mean, however, that steps or ramps had to be included in the interior to provide access to the remain- ing high-floor areas. Steps and ramps might introduce safety and space issues. Two innovations have facilitated the development of vari- ous low-floor concepts: independent rotating wheels (IRWs) and Einzelrad-Einzelfahrwerk (EEF) wheelsets. IRWs are wheels that rotate on the stub axle or an equivalent bearing medium; they may be steered as a pair by the vehicle articu- lation or built into a truck in accord with normal practice. EEF wheelsets have IRWs that are self steering. The yawing moment caused by the high angle of attack is used to steer the wheels, control being provided by a pivoting axlebar and a low-level linkage, which ensures that the wheels remain par- allel. They are used as single wheelsets. Zurich cars with EEF wheelsets also have car-bodyâcontrolled steering. Partial low-floor vehicles have been achieved in several ways. TCRP Report 2 used a categorization which can be use- fully applied: â¢ Category 1âVehicles with conventional motor and trailer trucks throughout; â¢ Category 2âVehicles with conventional motor trucks at each end but non-conventional center trailer trucks or wheelsets; and â¢ Category 3âVehicles with innovative motored and trail- ing running gear throughout. TCRP Report 2 also introduced a classification system for trailer trucks: â¢ T1 Four conventional wheels, two conventional axles; â¢ T2 Four IRWs, two cranked axles; â¢ T3 Four IRWs; â¢ T4 Two small IRWs built into articulation; â¢ T5 Two conventional wheels, one conventional axle, steered by articulation; â¢ T6 Four small wheels, two conventional axles; â¢ T7 Two IRWs steered by the articulation; and â¢ T8 EEF wheelset. Category 1 vehicles have low-floor areas between the trucks, so the trucks are not of the low-floor type. The pro- portion of low-floor area will be restricted by this approach. Since TCRP Report 2 was written, the Skoda Astra Streetcar has been introduced in the United States; this is a three- section articulated LRV with a low-floor center section. It is a Category 1 vehicle because the center section has no wheels suspended from the end sections through the articulation and is, therefore, outside the scope of this study. Category 2 is of interest because it includes the low-floor vehicles with a center truck having IRWs that are the subject of the current study. Table 2-1 provides data on the main types of vehicle produced in this category. Table 2-1 uses a notation to describe the wheel arrangement, which is described in the Glossary (Appendix B). The vehicle designs marked with an asterisk were first introduced in the United States. The table shows how much various manufacturers have been involved in these developments and the varieties of C H A P T E R 2 LFLRV Technology and Applications
7Year introduced Builder Model Number built Center truck type Wheel arrangement Sections Where used 1984 Vevey Be4/6 39 T6 B' 2' B' 2 Geneva, St. Etienne 1987 GEC Alsthom TSF 136 T2 B' 2' B' 3 Grenoble, Paris, Rouen, St. Etienne 1989 Vevey Be4/8 34 T6 B' 2' 2' B' 3 Bern, Geneva 1990 Socimi T8000 33 T3 Bo' 2 Bo' 3 Rome 1990 Duewag NGT6C/ NGT6D/ MGT6D/ 6NGTWDE 283 T8 B'1'1'B' 3 Bochum, Bonn, Brandenburg, Dusseldorf, Erfurt, Halle, Heidelberg, Kassel, Muelheim, Oberhausen, Rostock 1993 Bombardier T 78 T5 Bo'1'1'Bo' 3 Vienna 1994 Duewag/ Siemens Valencia type 31 T3 Bo' 2 Bo' 3 Lisbon, Valencia 1994 Duewag 6MGT 64 T3 Bo 2 Bo 5 Ludwigshafen Mannheim 1994 Duewag 8MGT 5 T3 Bo 2 2 Bo 7 Ludwigshafen Mannheim 1994 DWA/ Alstom NGT8D 25 T6 Bo' 2' 2' Bo' 3 Magdeburg 1995 Duewag NGT8 56 T6 Bo' 2 '2' Bo' 3 Leipzig 1995 Adtranz/ Bombardier GT6-70DN 45 T2 Bo' 2 Bo' 3 Karlsruhe 1995 DWA Bautzen Flexity Classic NGT6DD 47 T2 Bo 2 Bo 5 Dresden 1995 Bombardier Flexity Swift K4000 276 T2 Bo' 2 Bo' 3 Alphen, Cologne, Croydon, Istanbul, Minneapolis, Rotterdam, Stockholm *1996 Siemens/ Duewag SD- 600A/660A 79 T2 Bo' 2 Bo' 2 Portland 1996 ABB- Henschel Variotram 6MGT-LDZ 58 T3 Bo 2 Bo 5 Heidelberg, Ludwigshafen, Mannheim 1997 Tatra RT6N1 19 T3 Bo' 2' Bo' 3 Brno, Poznan, Prague 1997 Tatra KTNF6 36 T2/T3 B' 1' 1' B' 3 Brandenburg, Cottbus 1998 FIAT Cityway 28 T2/T3 Bo' 2 2 Bo' 5 Rome 1999 FIAT/Stanga T5000 54 T2/T3 Bo' 2 Bo' 3 Turin 1999 Alstom Citadis 401 68 T2 Bo' Bo 2 Bo' 5 Dublin, Montpellier 1999 Bombardier Flexity Classic 8NGTW 40 T2 Bo' 2' 2'Bo' 3 Kassel *1999 Breda Type 8 100 T2 Bo' 2 Bo' 2 Boston (continued on next page) Table 2-1. Category 2 LFLRVs. product that have been developed, partly because of the âmodularâ or âplatformâ approach that adapts a basic design to meet various specifications. The history of some of these developments is described in Section 2.2. The table also shows the extent to which the various cen- ter truck configurations have been applied. The types used have been T2, T3, T5, T6, and T8. The more recent develop- ments have not used the T8 and the T5 option only appears once. Use of the T2 and T3 categories of independent wheel center trucks is widespread and has been a sales success for various manufacturers. This type is generally regarded as having lower
technical risk than a 100-percent low-floor (Category 3) LRV but issues of high wheel wear on the center trucks are widespread. Some designs are more successful than others, and the inherent sensitivity of the arrangement allows minor adjust- ments to vehicle and truck design parameters to give signifi- cant benefits in running behavior. This has been borne out by the research undertaken. Vehicles with the T6 type of conventional, small-wheel truck have reportedly performed well. The small-wheel truck is always located fully underneath a body section and not mounted under a short âcenter section.â The truck is free to pivot and is not attached to the other body section. This may influence performance positively. Single wheelsets designs (T5 and T8 categories) have not been perpetuated beyond the early orders documented in TCRP Report 2. In particular the EEF wheelset-equipped cars have reportedly not performed as well as anticipated in all cases because of the high cost of maintaining the relatively complex steering system. Section 1.3 demonstrated that 100-percent low-floor cars are now achieving a high level of successful applica- tions in Europe and have taken a significant proportion of the market from the partial low-floor concept. One- hundred-percent low-floor cars offer the advantage of a uniform floor level as well as easier access, but often a uni- form floor level can only be achieved with some restriction on available floor space. There have been no applications of this type, which falls in Category 3, to date in the United States and Canada. The issue of adopting 100-percent low-floor cars was con- sidered in TCRP Report 2 (Chapter 3). The study concluded that introduction into the United States and Canada on entirely new systems might prove difficult because â¢ New systems might not wish to assume the potential liability for specifying lower buff loads, even though no technical reason was identified why this cannot be done. 8 Year introduced Builder Model Number built Center truck type Wheel arrangement Sections Where used Sharyo Bergen, Newark, Santa Clara 2000 Ansaldo- breda T69 16 T3 B' 2' B' 3 Birmingham 2000 Alstom Citadis 301 69 T2 Bo' 2 Bo' 3 Dublin, Orleans, Valenciennes 2000 Bombardier Flexity Classic M8DNF 34 T2 Bo' 2' 2' Bo' 3 Essen 2002 Bombardier Flexity Classic NF2000 NGT6 40 T2 Bo' 2' Bo' 2 Dessau, Halle 2002 CAF 8 T2/T3 B' 2 B' 3 Bilbao 2003 Bombardier Flexity Classic NGT6 26 T2 Bo' 2 'Bo' 3 Krakow 2003 Bombardier Flexity Classic NGTD12DD 32 T2 Bo' Bo' 2' 2' Bo' Bo' 5 Dresden 2003 Bombardier Flexity Classic NGT8'S' 60 T2 Bo' 2' 2' Bo' 3 Frankfurt 2003 Bombardier Flexity Classic SN2001 30 T2 Bo' 2' 2' Bo' 3 Schwerin 2003 Alstom Citadis 500 28 T2 Bo' 2' 2' Bo' 3 Kassel 2003 Leipzig Works Leoliner 37 T2/T3 Bo' 2' Bo' 2 Leipzig *2003 Siemens Avanto S70 44 T2 Bo' 2 2 Bo' 5 Houston, Paris, San Diego 2005 Siemens NGT6D 45 T2/T3 Bo' 2 Bo' 3 Ghent 2006 Bombardier Flexity Classic NGTD8DD 50 T2 Bo' Bo' 2' Bo' 5 Dresden 2006 Alstom Citadis 500 50 T2 Bo' 2 Bo' 3 Den Haag *2000 Kinki 187 T2 Bo' 2 Bo' 2 Hudson- Table 2-1. (Continued).
â¢ One-hundred-percent low-floor designs might not meet stringent U.S. and Canadian fire standards (ASTM E-119 was specifically cited). Ten years since the publication of TCRP Report 2, the greater availability and worldwide experience of 100-percent low-floor operation may now outweigh the liability issue. These issues are considered in Chapter 4 under âBest Practice for System Design,â and recommendations for research into how this type of vehicle might be introduced in the United States and Canada are included in Chapter 5. A notable development is the appearance of a significant number of 100-percent low-floor cars (Category 3 in TCRP Report 2) having conventional small-wheeled trucks through- out. The low floor is achieved by the use of 560-mm-diameter wheels and 5-percent ramps to allow the floor to clear the trucks, without introducing steps. These cars have been suc- cessful in sales terms and the researchers are not aware of any major dynamic/wear-related issues with them. This tends to support the conclusion of TCRP Report 2, which expressed optimism in regard to this particular concept. However, wheel contact stresses are higher with small wheels for a given axle load. One source (3) has suggested that the optimum arrange- ment for future LFLRVs would be to employ conventional motor bogies and a conventional small-wheeled trailer bogie in the center, based on experience with the existing car designs. 2.2 Product Development This section gives a brief overview of the products of the major suppliers that fall into the Type 2 LFLRV category. These products were known to the researchers when the research was completed and any omissions are accidental. TCRP does not endorse any particular product described here. 2.2.1 ALSTOM GEC Alsthom developed some of the earliest LFLRVs, the French Standard Type (TSF), which first entered service in 1987 in Grenoble. These vehicles are a three-section design with a short center section fixed to a truck with cranked axles and IRWs (Type T2). This company is now part of ALSTOM, which has devel- oped this technology into the modular âCitadisâ range. The Citadis is available in three configurations. Three of these are Category 2, the basic 301, 401, and 500 models having conventional motor trucks and an independent wheel center truck. The âRegio Citadisâ 500 model is designed for longer distance and higher speed routes and has an extra center truck. These are designed for use in shared running applications. ALSTOM also produces a version of the Citadis that is a Category 3 vehicle with IRW trucks throughout. The center truck of the Category 2 Citadis cars is the âArpegeâ type, a design that has no primary suspension, rely- ing instead on a flexible truck frame, resilient wheels, and coil spring secondary suspension at the corners of the frame. The design of the wheelsets incorporates a low-level driveshaft linking the wheels together. As such they are not truly IRWs. Table 2-2 summarizes some of the main deliveries made of these vehicles. 2.2.2 Kinki Sharyo Kinki Sharyo is the manufacturing arm of the Kintetsu Group of companies. They have worked with ALSTOM and have only supplied LFLRVs within the United States and Canada. The center trucks were developed by Fiat-SIG with assistance from PROSE AG. The truck design is conventional, employing cranked axles, chevron rubber primary suspen- sion and air bag secondary suspension. Kinki Sharyo has a large part of the U.S. market; this has been a significant development in recent years. They intro- duced LFLRVs into the United States which now have mil- lions of miles of operating experience. One hundred and forty-five vehicles have been delivered and more are on order. The vehicles were supplied to NJ TRANSIT and Santa Clara Valley Transportation Authority (VTA). They are supplying low-floor center sections to convert existing LRVs in Dallas to LFLRVs. 2.2.3 Ansaldobreda This company was formed by the merger of two Italian firms Ansaldo and Breda; the latter had been a vehicle (e.g., locomo- tives, coaches,multiple units,metro cars,and streetcars) builder. The company has supplied many LRVs, including cars for the Cleveland Transit Authority and San Francisco Muni, but until recently had built relatively few LFLRVs. The early designs for Ansaldobreda LFLRVs were delivered to the Massachusetts Bay Transportation Authority (MBTA) in Boston, Midland Metro (UK), Oslo Tramways (Norway) and Lille Transpole (France). The Oslo car is a Category 1 with all conventional trucks while the Lille cars are virtually Category 3 cars with a large low-floor area and a very different running gear system that incorporates 9 Product Main cities Approx. numbers built Citadis 301 Dublin, Orleans, Valenciennes, 69 Citadis 401 Dublin, Montpellier 68 Citadis 500 Den Haag, Kassel 78 TSF (French Standard) Grenoble, Paris, Rouen 116 TOTAL 331 Table 2-2. ALSTOM (and predecessor) Type 2 LFLRVs.
conventional motor trucks fitted under a high-floor area containing the cab and other electrical equipment. The Boston MBTA and Midland Metro cars are classic Category 2 configu- rations, but the center trucks differ in their design. Sixteen Category 2 LFLRV vehicles are in use on the Mid- land Metro and 100 have been ordered and some introduced into service by Boston MBTA. Ansaldobreda also offers a modular range known as Sirio, but it is a Category 3 100-percent low-floor design not rele- vant to this study. 2.2.4 Bombardier The âFlexity Swiftâ LFLRV cars that run on the Minneapo- lis Metro Transit are part of a range of similar products. Bom- bardier developed the standard Flexity Swift range with the first examples appearing in Cologne in 1995. Very similar vehicles have also been built for Istanbul, Croydon, Rotter- dam and Stockholm. This product is a classic Category 2 design with three sections, and an IRW truck under the short center section. It is intended for light rail systems with a mix of street track and segregated running. Through mergers and takeovers, Bombardier has also inherited a range of other Category 1, 2, and 3 designs, which it now sells under the same âFlexityâ brand. Of relevance to this study is the âFlexity Classicâ design, originally developed by DWA as the âLF2000.â This is a Category 2 design similar in concept to the Flexity Swift but with a different configura- tion of vehicle bodies. There is no small center section, with IRW trucks with freedom to yaw instead being placed under full-length body sections. This design has been very popular in Germany, notably with Frankfurt am Main where an option for more Category 3 cars was abandoned in favor of this more traditional type of vehicle. Bombardier offers a Category 3 product, Flexity Outlook, which uses these trucks to obtain a 100-percent low floor. The company claims that these trucks give much better running performance than IRW alternatives and, as such, no longer markets its inherited IRW Category 3 designs. Table 2-3 sum- marizes some of the main deliveries of these vehicles. 2.2.5 Siemens/Duewag Siemens (formerly Duewag) based its first Category 2 design on the EEF self-steering wheelset concept. Many of these vehicles were constructed, but Siemens stopped devel- oping this design in the 1990s. The company produced some more typical Category 2 vehicles and the center trucks for the Siemens Duewag/Adtranz (later Siemens/Bombardier) GT6- 70DN cars introduced in Karlsruhe, Germany, beginning in 1995. Most relevant to the U.S. market are the SD-600 and SD- 660 types. These are a Category 2 design of which there are 79 on the TriMet system in Portland, Oregon. Siemensâ sec- ond product is the âAvantoâ type, a Category 2 design hav- ing a short center section with cranked axles and IRWs. These operate in Houston, on new infrastructure. Table 2-4 summarizes some of the main deliveries of these vehicles. Siemens offers the âCombinoâ range as its standard product. This is a Category 3 100-percent low-floor design that has all IRWs. 2.2.6 Summary Table 2-5 summarizes the statistics of the vehicles considered in this review and indicates the scale of U.S. 10 Product Main cities Approx. numbers built Flexity Classic Adelaide, Bremen, Dessau, Dresden, Essen, Frankfurt-am-Main, Halle, Kassel, Krakow, Schwerin 389 Flexity Swift Alphen, Cologne, Croydon, Istanbul, Minneapolis, Stockholm 255 GT6-70DN Karlsruhe 70 T Vienna 3 Variotram Heidelberg, Ludwigshafen, Mannheim 42 TOTAL 759 Table 2-3. Bombardier (and predecessor) Type 2 LFLRVs. Product Main cities Approx. numbers built 6MGT Ludwigshafen, Mannheim 8MGT Ludwigshafen, Mannheim Avanto S70 Houston, Paris, San Diego Buenos Aires Buenos Aires Lisbon Lisbon MGT6D Bochum, Brandenburg, Erfurt, Halle, Heidelberg, Muelheim, Oberhausen 146 611 25 40 56 71 52 2 72 10 9 5 34 64 NGT6C Kassel NGT6D Bonn, Dusseldorf 6NGTWDE Rostock NGT8 Leipzig NGT8D Magdeburg SD-600A Portland SD-660A Portland Valencia Valencia TOTAL 25 Table 2-4. Siemens (including Duewag) Type 2 LFLRVs. Supplier group Cars % of total Cars US US % of supplier group % of US total ALSTOM 331 15 0 0 0 Bombardier 759 34 24 3 7 Breda 116 5 100 86 27 Kinki Sharyo 145 7 145 100 39 Siemens 636 29 98 15 27 Other 238 10 0 0 0 TOTAL 2225 100 367 17 100 Table 2-5. Summary of vehicle numbers for Category 2 type LFLRVs.
applications and how the products used differ from experi- ence generally. 2.3 Application in the United States Table 2-6 summarizes the deliveries of the Category 2 LFLRVs in the United States with center trucks having IRWs. There are six basic car types, originating from three separate supply strands (i.e., Siemens/Duewag;  Breda; and  Kinki Sharyo and Bombardier). Combining these car types with the eight transit systems with differing characteristics provides varied experience. Appendix C provides more detailed information about most of these cars. Appendix D provides details of the systems over which these vehicles operate. The systems are grouped as old or new as follows: â¢ Oldâtraditional streetcar systems opened before 1950, including those that have been modernized and extended but not reconstructed to modern LRT standards; and â¢ Newâmodern LRT systems opened since 1970. All seven transit agencies were surveyed for specific informa- tion about these cars, track standards, experience with the use of the center trucks, and any mitigation they may have intro- duced for overcoming issues. The following sections describe the experience in each U.S. city, concentrating on those that have the most vehicles or the most experience of performance issues. The informa- tion is taken from a literature search, a questionnaire, visits to some of the systems, and correspondence as explained in Appendix A. 2.3.1 Portland TriMet Infrastructure The Tri-County Metropolitan Transportation District of Oregon (TriMet) operates a 33-mile-long light rail system in Portland. The first section opened in 1986. There is also a short streetcar line and a vintage trolley service. LFLRV Fleet The first batch of Portland cars were on order when TCRP Report 2 was published. There were 46 cars and 6 more of this type (SD-600A) were added later. Portland also took delivery of 27 cars of type SD-660A later, bringing the total fleet of LFLRVs to 79. TriMet has pointed out that the SD-600A and SD-660A are virtually identical, so these are considered as one type from here on. Details of the Center Trucks The center truck frames are rigid and have independent resilient 26-inch (660-mm) Bochum wheels on a cranked drop axle. The primary suspension is provided by conical rubber chevron springs; the secondary suspension is pro- vided by coil springs controlled by lateral and vertical dampers. Resilient traction links control yaw. The center truck is braked. No vehicle-mounted lubrication is used. Measures Undertaken When These Vehicles Were Introduced A computer model simulation of the routes was used when the vehicles were selected in order to check that the vehicles would be suitable. Vehicles were also test run on the routes before being accepted. The supplier provided operation and maintenance manuals as well as training. Experience Using These Vehicles TriMetâs experience in using these vehicles has generally been good. Wheel wear has been higher than for other types of car, but passengers have not raised issues about noise and ride comfort, and there have been no derailments. There would be no issue about introducing further cars of this type or other types of LFLRV. TriMet is required to comply with the FTA Guidelines for Design of Rapid Transit Facilities in which interior noise should not exceed 78 dBA at 55 mph except in tunnels. TriMet has exceeded these standards with wheels that are rough or with flat spots and on corrugated rail. Measures To Reduce Issues Wheel flange wear on the center truck occurs at a higher rate than on the motor trucks as TriMet expected. The LFLRV cen- ter truck tends to produce more squeal than motor trucks. About 20 wayside lubricators have been installed at sharp 11 City/system LFLRVs Years supplied Portland MAX Siemens/Duewag SD-600A and SD660A 1996-2004 Boston MBTA Breda Type 8 1999-2003 NJ Transit Hudson-Bergen and Newark Subway Kinki Sharyo 2000-4 San Jose, Santa Clara VTA Kinki Sharyo 2001-4 Minneapolis Metro Transit Bombardier Flexity Swift 2003-4 Houston METRO Siemens Avanto S70 2003-4 San Diego SDT Siemens Avanto S70 2004 Table 2-6. Category 2 LFLRV deliveries, North America.
curves in embedded track to mitigate wheel squeal from both low- and high-floor LRVs. These lubricators have been used for the past 2 years on girder rail, embedded track, and some open track; they also help reduce wheel and rail wear. They are con- sidered to have been effective. Lubricant is pumped through a 1/4-inch-diameter hole in the rail head at the wheel/rail con- tact area. On open track, TriMet also has about 10 wayside lubricators. Figure 2-1 illustrates a wayside lubricator. Residents have complained of noise from vehicles, and readings of 80 dBA have been made. This has been mitigated by rail grinding and keeping wheel profiles in good condition. 2.3.2 Massachusetts Bay Transportation Authority (MBTA) Infrastructure MBTA operates 31 miles of streetcar lines in Boston. These lines developed out of a system that had its origins 150 years ago. The 25-mile-long Green Line, where LFLRVs are used, dates in part from 1897. Parts of this line are underground subway. Unlike the Portland Metropolitan Area Express (MAX) system, the Green Line is a long-established streetcar network with many potentially challenging infrastructure features. It is also one of the busiest systems of its kind in the United States and Canada, with relatively intense and com- plex services. The track used on the Green Line has relatively severe geometry. Curves can be as tight as a 42-ft (12.8-m) radius with no tangent track between reverse curves. LFLRV Fleet MBTA ordered 100 cars from Ansaldobreda, the first of which was delivered in 1998 for testing (4). They were desig- nated Type 8 by MBTA and have been used only on the Green Line. Figure 2-2 shows such a car. Measures Undertaken When These Vehicles Were Introduced The supplier ran a computer simulation of the Type 8 design, based on track conditions considered appropriate. Test running before operation in Boston was limited to 10 mph on a short test track, but trial running was also undertaken on the Green Line. The manufacturer provided specialized operations and maintenance training and operations and maintenance manuals. Details of the Center Trucks Figures 2-3 and 2-4 show views of the center truck used on the Type 8 cars. As explained in Section 2.2.3, this car design is unique to Boston. The center truck frame is flexible. In plan view, it has two L-shaped elements with a spherical joint connection at the end of the shorter arm of each element (see Figure 2-5). The IRWs are mounted on a low-level cranked axle so that they are constrained as if they were on a conventional solid axle. The primary suspension consists of stiff rubber bushings between the truck frame and the axle. These are formed of metal external and internal rings with rubber between them. The rubber element is configured so as to give a variation 12 Figure 2-1. Wayside lubricator. Figure 2-2. MBTA Type 8 LFLRV on the Green Line in Boston. Figure 2-3. Center truck of MBTA Type 8 car (general view).
between vertical and longitudinal stiffness. Figure 2-6 illus- trates this arrangement. Four air springs are used to support the bolster; these are arranged inboard of the axles, and each pair is linked from side to side by a common leveling valve. The two ends are linked through a relay valve, which permits cross feeding. This arrangement is controlled by two lateral dampers. Figure 2-7 illustrates this arrangement. As illustrated in Figure 2-8, the center truck has an anti-pitching system using a torsion rod to provide stiffness. The roll control of the entire vehicle and of the center section is largely performed by transverse rods on the roof; the joints are spherical ball bearings in line with the relative trailing axle. Figure 2-9 illustrates this arrangement. The vertical pitching of the center section is controlled by the air springs and anti-pitching bars; there is no pitch damping. Experience Using These Vehicles Since the Type 8 cars were introduced in 1999, some derail- ments have occurred. MBTA has also experienced excessive wheel and rail wear associated with these cars. There have been issues with interior noise resulting from the difficulty of damping the noise coming from the wheel-rail interface within the tight space envelope. Ride comfort requirements are met, although some yaw and pitching movements are noticeable. There have been no complaints from passengers however. Measures To Reduce Issues In 2001, investigations began to study the causes of the derailments using simulations and a special test track facility. As a result a new wheel profile was introduced and track maintenance standards were altered (5). Derailments occurred on tangent track because of lateral disturbances caused by track irregularities. These irregulari- ties were a combination of gauge widening and cross level variation, which created a large angle of attack and caused wheel climbing. Vertical movement of the center truck causes a truck yaw rotation because of the arrangement of the trac- tion links. This is noticeable at speeds above 35 mph, and, at speeds above 40 mph, the lateral-to-vertical-force ratio is exceeded, increasing derailment risk. The manufacturer 13 Figure 2-4. Underside view of the center truck (MBTA Type 8). Figure 2-6. Cranked axle arrangement, IRW and primary suspension (MBTA Type 8). Figure 2-5. Articulated center truck frame (MBTA Type 8). Figure 2-7. Air spring control system (MBTA Type 8).
introduced a modification that allows the cars to operate up to 50 mph without exceeding the limit at which the lateral-to- vertical force ratio might cause derailment. A modification has improved the control of yaw on the center truck. The modification consists of a virtual pivot with traction rods. An asymmetric arrangement of two traction rods ties the bolster and truck frame together. Smaller âdog bonesâ are tied to the truck frame to prevent rotation of the wheelsets. The bolster-to-frame arrangement is being changed to a design that provides greater rotational freedom between the truck and car body by introducing a virtual cen- ter pivot with limited rotational freedom. Part of the Green Line (the B Line) was changed to the new track maintenance standard, and the railhead was re-profiled to remove the lip that had developed from wear. The mainte- nance interval was reduced from 6 to 3 months. Type 8 cars received the new wheel profiles first, followed by the earlier Type 7 high-floor cars. These earlier cars were not modified but are wearing to the new profile. At first wheels had to be re-profiled every 2,000 miles to keep them within limits, but now wheels can be used in excess of 30,000 miles before re-profiling is necessary. No derailments result- ing from dynamics have occurred since March 2003. Excessive wheel wear has been greatest on the motor trucks, with localized wear at the flange tip resulting in the flange angle degrading rapidly. At one time it was necessary to re-profile the wheels as often as every 2,000 miles, as men- tioned. This occurred because of changing the flange angle from the older Green Line standard of 63 to 75 degreesto mit- igate derailment issues. This was a transition issue and was overcome by seven measures: â¢ Very close monitoring of wheel profiles, â¢ Checking maintenance tolerances by use of dynamic modeling, â¢ Gauge face grinding of the rail, â¢ Design and grinding of a new railhead profile to promote better steering and reduced contact, â¢ Changing the profile on other cars in the fleet, â¢ Grouping cars with the new profile on one line, and â¢ Tests of a friction modifier. The early test results of the use of a stick lubricator on the front and back flanges of the wheels on the motor trucks were inconclusive and were based on limited data. As mentioned, the overall result has been to increase the mileage between truing to more than 30,000 miles. There has also been excessive rail wear from the same cause and re-grinding has reduced this issue. This has, however, shortened the potential life of the running rail. The most severe wear issues occur on tight-radius curves (less than 100-ft radius) and are caused by all vehicles. MBTA believes that IRWs actually may have lower contact forces on these sharp curves. The addition of sound-deadening panels beneath the floor and inside the articulation bellows reduced the noise level within the vehicles to limits that met the appropriate standards. 2.3.3 Newark Subway Infrastructure NJ TRANSIT operates the Newark Subway, which is a short (5-mile-long) remnant of a much larger streetcar network. This route was built in a tunnel in 1935 and has survived as a relatively busy small transit system, with an extension now 14 Figure 2-8. Anti-pitching system (original design) (MBTA Type 8). Figure 2-9. Roof-mounted rods to prevent inter-section roll (MBTA Type 8).
under construction. The subway uses traditional streetcar technology, where the wheels have narrow tires, although it does not have any street running sections; it does have tight curves at the city center end of the route. LFLRV Fleet NJ TRANSIT introduced 18 Kinki Sharyo LFLRVs in 2000 for use on the Newark system (see Figure 2-10); this fleet is being expanded. Details of the Center Trucks The center trucks were supplied by Fiat-SIG (see Figures 2-11 and 2-12). The center truck frames are rigid âHâ type and have 26-inch (660-mm) Bochum IRWs on a low-level âcrankedâ beam referred to as an âidler axle.â The primary suspension is provided by rubber chevron springs; the sec- ondary suspension is provided by air springs. Resilient trac- tion links control yaw. The center truck is linked to the end sections by bearings under the articulation and the relative movement is controlled by a pair of Z-links and two dampers above one of the joints. These Z-links and dampers are roof mounted (see Figure 2-13). The center truck is braked and has track brakes. A REBS grease spray lubrication system has been tried on one car for over a year as an experiment. The REBS grease spray lubrication system has two nozzles for each axle end and sprays REBS friction modifier on the wheel. The vehicles are fitted with a special wheel profile (see Figure 2-14), which is appropriate to the track geometry of the subway. Measures Undertaken When These Vehicles Were Introduced A computer model simulation of the routes was used when the vehicles were selected in order to check that they would be suitable. Vehicles were also test run on the subway and else- where before being accepted. The supplier provided opera- tions and maintenance manuals and training. Experience Using These Vehicles NJ TRANSITâs experience in using these vehicles has gen- erally been good although issues have occurred. Wheel wear has been higher than for conventional cars. Center truck wheels wear faster than those on the drive axles. Wheel turning started after 100,000 miles and was repeated at 30,000-mile intervals. This was causing the flange thickness to increase, so profile correction is necessary as part of the wheel turning. Although the subway is small, the depot is equipped with a modern underfloor wheel lathe. NJ TRANSIT staff have observed that the truckâs curving behavior on curved tracks and switches probably causes the excessive wear. The hardness of the tires was designed to give optimum wheel and rail wear rates. Excessive rail wear generally occurs on curved track and typically on switches and crossings. The highest rate of wear occurs at the reversing loops in Penn Station. These reversing 15 Figure 2-10. NJ TRANSIT Kinki Sharyo LFLRV in Bloomfield workshop. Figure 2-11. Center truck (NJ TRANSIT Kinki Sharyo LFLRV). Figure 2-12. Lateral bump stops on the center truck (NJ TRANSIT Kinki Sharyo LFLRV).
Although passengers are not carried on this section, any excessive noise affects passengers waiting at the adjacent platforms. Ride comfort has not been an issue. There would be no issue about introducing further cars of this type or other types of LFLRV on the Newark Subway. Measures To Reduce Issues NJ TRANSIT has introduced house tops to stop derail- ments from occurring. House tops are fitted to all switches, except those operated infrequently. The noise issue on the Penn loop is being managed by using lubrication, gauge widening, flange way widening and installa- tion of restraining rail at both rails (see Figures 2-15 and 2-16). 16 Figure 2-15. Fully guarded switch in Penn Station. Figure 2-14. Newark city subway wheel profile. Figure 2-16. Rail surface friction conditioner at Penn Station, showing lubricant on rail surface. Figure 2-13. Roof-mounted Z-links and dampers (NJ TRANSIT Kinki Sharyo LFLRV). loops have radii of 60 and 82 feet. All cars pass around them, but they are not carrying passengers at the time. The inner rail on these curves is more affected. NJ TRAN- SIT predicts the need to replace the rails on these loops every 10 years but might be able to extend this to 15 by optimizing the performance of the wayside lubricators. Three derailments have occurred, but these have all hap- pened at slow speed on switches. The cause has been identified as the tendency of the center truck to curve. This side curving can cause derailment because of adjustment of the switch blade under the stock rail, thereby causing a step up and asso- ciated with a cross leveling of more than 1â8 in. toward the point of the switch. This has been identified as the cause in all cases. Noise levels are high on the Penn loop; figures of 109 dBA have been recorded when speed has exceeded 5 mph.
Gauge widening will increase the angle of attack, but in this sit- uation the derailment risk is low. There are 12 lubricators in the yard to cover all turnouts and sharp curves (see Figure 2-17). Also there are four way- side friction modifiers. Two are on the Penn loop and the others are on a 100-ft-radius curve close to an apartment building. 2.3.4 Hudson-Bergen NJ TRANSIT NJ TRANSIT also introduced 29 LFLRVs of the same type as used on the Newark Subway onto the new Hudson-Bergen line in 2000. A further order is pending. The Hudson-Bergen uses the AAR1B wheel profile (51â4 inches wide) and a different wheel back-to-back dimension (533â8 inches compared with 541â8 inches on the Newark Sub- way). No specific issues have been reported by NJ TRANSIT. Such issues as have been encountered with these cars on the Newark Subway are mainly associated with the more extreme geometry of older streetcar track. Hudson-Bergen is re-pro- filing all wheels at 30,000 miles, so wear may not have been identified as an issue. The maintenance of the cars is not car- ried out directly by NJ TRANSIT, but by the car builder under the Design, Build, Operate, and Maintain (DBOM) contract. 2.3.5 Santa Clara Valley Transit Authority (VTA) Infrastructure The Santa Clara VTA system of San Jose is a newly built light rail; it was inaugurated in 1987. The route is 30 miles long. The route uses both girder (Ri59) and standard (115 RE) rail. The minimum curves are 30 m (98 feet) on the route and 25 m (82 feet) in the depot. LFLRV Fleet Kinki Sharyo has supplied a fleet of 100 LFLRVs to the Santa Clara VTA; these have an ALSTOM traction system (see Figure 2-18). Thirty were supplied in 2001-2 and a fur- ther 70 were supplied in 2004. Mileage is 30,000 to 120,000 miles per year per vehicle, with 42 required to provide the service. Details of the Center Trucks The center truck frames are rigid and have full inde- pendent resilient 26-inch (660-mm) Bochum wheels. The primary suspension is provided by rubber chevron springs, the secondary suspension is provided by air. The center truck cannot yaw because it is integral with the central module. The center truck is braked. No vehicle-mounted lubrication is used. These cars are very similar to those in use by NJ TRANSIT (see Figures 2-19 and 2-20). Measures Undertaken When These Vehicles Were Introduced Track is ground to provide uniform wear of the running surface including asymmetric railheads on curves. Vehicles were test run on the route before being accepted and the fact that NJ TRANSIT were already operating similar vehicles was important. The supplier provided operation and maintenance manuals and training. 17 Figure 2-17. Friction conditioners for rail flange and guide rail in the workshop area. Figure 2-18. VTA Kinki Sharyo LFLRV.
the truing interval and hence extend the life of wheels. Figure 2-21 illustrates this measure. There have been issues with railhead corrugation on embedded track since the system was opened and this has continued with the introduction of LFLRVs. Also anticipating issues,VTA installed wayside flange lubri- cators in order to reduce wheel squeal on sharp curves. The system is also experimenting with surface friction condition- ers (see Figure 2-22). These measures are provided in order to reduce wheel squeal for all types of car. All vehicles are fitted with the supports and holders for flange, surface, and wheel back conditioning (see Figures 2-23 through 2-25). All the sticks have, however, been removed because of concern about extending braking distances. Because of the high deceleration rate, the friction brake on the center trucks is heavily used. The brake discs are close to the wheel and the wheel bearings, causing the grease to warm up. The bearings have to be overhauled regularly because the properties of the grease change from this heat. Center trucks are showing slightly more flange wear than motor trucks and these trucks are noisier than motor trucks or older conventional cars. Lubricators have been installed and these solve noise issues most of the time. Derailments have occurred, but these have all been because of operator error and, in one case, an automobile collision. The moments transferred through the car bodies caused a high angle of attack of the wheels of the center truck (see Figure 2-26) 18 Figure 2-22. Surface friction conditioner, Santa Clara. Figure 2-20. Roof-mounted articulation dampers and Z-link. Figure 2-21. Alteration to the VTA wheel profile. Figure 2-19. Cranked axle under the articulation (VTA Kinki Sharyo LFLRV). Experience Using These Vehicles VTAâs experience in using these vehicles has generally been good. There have been no wheel or track wear issues or derail- ments and ride comfort has not been an issue. There would be no issue about introducing further cars of this type or other types of LFLRV to the system. Noise is excessive on sharper curves (less than 600 feet radius), but this occurred with high-floor cars as well. The fleet has now accumulated more than 4 million miles and the VTA and its customers are very pleased with the per- formance and ride comfort of these vehicles. No hunting, noticeable resonance in the suspension, or other unpleasant side effect is attributable to the low-floor technology. Both interior and exterior noise emissions and vibration are within specification. Measures To Reduce Issues The wheel profile is being changed so as to provide an extended transition between the conical part of the running surface and the flange. This is being done in order to reduce
2.3.6 Minneapolis Metro Transit Infrastructure The Minneapolis Metro Transit âHiawatha Line,â a new light rail system opened partly in June 2004 and fully in December 2004, is 12 miles long (6). LFLRV Fleet The Hiawatha Line fleet consists of 24 Bombardier Flexity Swift type LFLRVs. These vehicles are based on the K4000 cars used in Cologne. Details of the Center Trucks The center trucks have IRWs. These trucks have radial arm suspension with the arms linked by a horizontal rod. The pri- mary springs are rubber and the secondary suspension is pro- vided by coil springs. Experience Using These Vehicles Operating experience is limited, although test running began in March 2003. A low-speed derailment occurred in a maintenance yard in March 2005 (7). This was caused in part by excessive wheel wear, and the system instituted more reg- ular inspections as a result. The curve was said to be tighter than on the service route. Also, varying wheel wear had been found on the wheels of the center trucks on 22 of the LFLRVs, and they were still under warranty. 2.3.7 Houston MetroRail Infrastructure The MetroRail Red Line is a light rail system that began operation in Houston, Texas, in January 2004. It is 71â2 miles long and part of the Metropolitan Transit Authority of Har- ris County. Track geometry is not severeâthe minimum curve being a 125-ft (38.1-m) radius. Most of the track is con- ventional 115 RE rail, although 80 percent of the route is embedded. 19 Figure 2-24. Holder for the wheel tread friction conditioner. Figure 2-25. Holder for the wheel back face friction conditioner. Figure 2-26. Side collisionâthe center truck derails because of the reaction of lateral loads. Figure 2-23. Holder for the wheel flange friction conditioner.
LFLRV Fleet Eighteen Siemens Avanto S70 LFLRV cars have been suppliedâdelivery began in 2003. There has been over 2 yearsâ of experience of operating this type of LFLRV; these are the only type of vehicles used on the system. Speeds have been limited to 40 mph (see below) although the cars can reach higher speeds. Details of the Center Trucks The Avanto vehicles have IRWs on the center trucks. The design uses cranked axles and a rigid center truck frame. The primary suspension consists of eight conical chevron rub- ber springs mounted on the inboard side of each wheel on the axle flange. The secondary suspension uses high-pressure hydraulic springs that maintain the car-body floor to plat- form height by means of six level sensors. Lateral damping is used, and yaw is controlled by means of resilient traction links. Three stabilizing links are used across the center sec- tion. Resilient wheels are used; Figure 2-27 shows the wheel profile. Measures Undertaken When These Vehicles Were Introduced Siemens undertook a computer model simulation of the route to check that the Avanto would be suitable. Speeds were restricted to 40 mph. Experience Using These Vehicles Wheel wear has been double the expected rate and has been occurring on both the tread and the flange. Some local- ized track wear, associated with sharp curves in the yard, has been experienced, but generally track wear has not been a issue. The system uses jointed trackânoise has been experienced on rail joints, expansion joints, and sharp curves. There have also been noise issues arising from flat spots on wheels. Vehicle ride is adversely affected by the uneven wheel wear; it is more appar- ent on tangent track. Noise and uneven ride are more noticeable on the center truck. Measures To Reduce Issues To overcome noise issues, MetroRail is providing continu- ous welded rail, top of rail friction modifiers, and lubrication of the flange ways within curves. These measures significantly reduce squeal, vibration, and crabbing and, therefore, reduced noise both inside and outside the cars. MetroRail does not see the vehicle ride issue as requiring mitigation at present. 2.3.8 San Diego Metropolitan Transit System (SDT) Eleven more Siemens Avanto S70 cars have been supplied to San Diego for use on the Green Line, which opened July 10th 2005. This is an extension of a much larger system, which has been using high-floor cars and which opened its first route in 1981. When investigations were made for this report, only one car on the system was under test, so there was no experience from which to draw conclusions. 2.4 Summary of Experience Table 2-7 summarizes performance issues in the United States to date based on the questionnaire results. The table expresses how the transit systems themselves see their issues and the extent to which they have been able to manage them âin house.â Only those systems that provided questionnaire responses are included. The more serious issues (in terms of safety and cost) are occurring on the older systems, so application of this new technology to an established network can be expected to be more problematic. This seems to be mainly a function of the track geometry associated with such systems. Older systems may also need to adapt maintenance practices to suit the new types of car. Issues similar to those experienced with this type of vehi- cle in the United States have occurred in other parts of the world. Where these are known, they appear very similar. In examining the performance issues, the researchers con- sidered possible differences in practices and standards between Europe and the United States to see if there was any evidence that this might have had an influence. 20 Figure 2-27. Wheel profile.
No significant differences were seen. This is discussed more in Chapter 3. 2.5 European Experience with This Type of Vehicle As indicated in Table 2-1, numerous LFLRVs with a center truck of this type and IRWs operate in Europe. The experi- ence of the European team members working on this research project was that, although similar issues had emerged in Europe, such issues tended to be less serious and were now being effectively managed. One German system that has been using a relatively large fleet of cars of this type for 10 years has had the following experience: â¢ There was more wear on IRWs than other wheels. â¢ Trailer truck wheel wear was roughly the same as motor truck wear, whereas it would normally be expected that wheels on motor trucks wear faster. â¢ Noise levels had been expected to reduce with IRWs because of their improved curving performance, but the noise levels remained the same. â¢ Performance issues were found to be worse on badly aligned or maintained track sections. Re-profiling of wheels tends to be in the range 10,000 to 40,000 miles, but IRWs typically are at the lower end of this range. Small-diameter wheels have been used as an alternative to IRWs, but these have their own issues, so it is an issue of bal- ancing the overall performance of these options in the specific application. Derailments occurred on another system where 10-percent low-floor cars are being used. These vehicles have IRWs but combine these with a more complicated body configuration, allowing more degrees of freedom. There has been a tendency to revert to partial low-floor vehicle solutions to avoid the increased wear and other issues associated with 100-percent low-floor cars of this type. 2.6 Trends The U.S. systems studied are not proposing to replace their LFLRVs with high-floor cars and will probably expand the use of LFLRVs. Sometimes this will be in situations where they have not been used before (e.g., a planned street running exten- sion of the Newark Subway). Other cities will introduce them, although the possibility of introducing other configurations of partial low-floor vehicle or 100-percent low-floor vehicles may eliminate the need to do this. Given that older systems may have more difficulty intro- ducing these cars than systems that can be designed to accom- modate them, it is interesting to consider what other cities with âtraditional streetcarâ systems are planning. In June 2005, the Toronto Transit Commission initiated a procurement process for low-floor vehicles to replace 96 existing streetcars. Four issues may make this process difficult: â¢ The use of single-point track switches that may cause issues for IRWs, â¢ Curve radii of 36 feet (inside rail), â¢ Low axle load requirements, and â¢ Prolonged 8-percent and some 7.5-percent grades that favor vehicles with all axles powered (8). The Southeastern Pennsylvania Transportation Authority (SEPTA) started a procurement for LFLRVs in 1998, but the process was cancelled because of the significant costs. The cost-driving factors included â¢ Curve radii of 35.5 feet; â¢ Non-standard (5 feet 21â4 inch) gauge, which means that vehicles have to be designed specially; â¢ Clearance requirements limiting the length and width of cars; and â¢ The small size of the order (12 vehicles). SEPTA plans to replace 141 cars eventually and will re-eval- uate the use of LFLRVs then (9). 21 System Portland Boston Newark Santa Clara Houston San Diego Derailments No Yes Yes No No Excessive wheel wear No Yes Yes No No Excessive track wear No Yes Yes No No Excessive trackside noise No Neutral No Yes Neutral Excessive interior noise No Yes No No Yes Excessive poor riding No Neutral No No No Mitigation introduced Yes Yes Yes No Yes Mitigation successful Yes Partly Partly N.A. Partly Too early to say Table 2-7. Questionnaire view of the extent and seriousness of problems.
Another trend is the increase in sales of âstandardizedâ designs, permitting comparison of almost identical models on different systems worldwide. Global standardization has only a limited relevance to the U.S. and Canadian market because of the different stan- dards that apply compared with the European light rail market, which is much larger. Despite this, two products in use in the United States and Canada may be directly com- parable with experience elsewhere. The Minneapolis vehi- cle belongs to the Bombardier Flexity Swift family and is similar to vehicles operating in Cologne (Germany), Alphen an der Rijn (Netherlands), Stockholm (Sweden), Istanbul (Turkey), and Croydon (UK). The Houston/San Diego Siemens âAvanto S70â design, also now on order for the Charlotte Area Transit System, has also been ordered by Paris RATPâalthough this latter order has not entered service yet. This is suitable for the U.S. and Canadian mar- ket because the European design was intended for shared operation of LRVs on heavy rail routes and, therefore, meets U.S. buff load requirements. 22