Trams Making Way for Light Rail Transit
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Feature New Promise of LRT Systems Trams Making Way for Light Rail Transit Shigenori Hattori medium-capacity, electric cars running on key part of medium-capacity urban transit Introduction rails. The cars are about 2.65-m wide and systems supplemented by links to cars, operate on their own right of way over buses and other transportation modes In 1978, the city of Edmonton in Canada elevated track, underground, etc., through Transportation Demand opened the world’s first urban transport permitting higher operating speeds. This Management (TDM) strategies. system based on the Light Rail Transit (LRT) type of definition could also include many LRT systems fulfil their role as medium- concept discussed in this article. Over suburban railways. capacity urban transit systems by the next 25 years, LRT systems have been In Japan, LRT systems are typically viewed operating articulated cars that can be up built in more than 70 cities worldwide. as sharing the road with motor vehicles, to 40-m long and sometimes the entire Of the approximately 350 tram systems like the trams in Grenoble and Strasbourg. train set can total 100 m. now in operation, about 30% can be Although such systems are known as trams Although some tram operators in Japan described as LRT systems, because they or streetcars in Europe and North America, are modernizing by introducing low-floor have been refurbished and modified to it is often assumed that even low-floor light rail vehicles (LF-LRVs), trams are still LRT standards. trams are not LRT systems. not highly regarded as an urban transit Due to historical differences and different Many Japanese cities had tramways in the mode because most rolling stock consists approaches taken when introducing light early 20th century but most abandoned of 13-m or so bogie cars that are similar rail systems, the term ‘LRT’ means one them in the postwar period of rapid growth to buses. Consequently, we must explain thing in Japan and another in Europe and in private-vehicle ownership when trams the effective role LRT systems play in North America. This article examines were seen as out-of-date. However, the urban transit in many European and North tramways and LRT systems bearing in last 20 years have seen renewed interest American cities to create a consensus mind the different definitions and the as it becomes clear that many LRT systems favouring upgrading of Japanese trams to differences in rolling stock, lines and in European and North American cities LRT systems. Unfortunately, the operations. are helping to reduce automobile conditions in Japan are still not right to emissions and revitalize city centres. reach this consensus. Moreover Japan’s greying population is Japanese Definitions of LRT creating further demand for barrier-free Modernization of urban transit using low-floor light rail Light Rolling Stock In Japan, there is renewed interest in the vehicles. The Japanese are beginning to possibilities of tramways and the mass see trams as a way to reduce urban Trams in Japan came to be seen in a more media use the term ‘LRT’ frequently. pollution and improve city life. favourable light in 1997 when Kumamoto Moreover, different writers in different Even so, the old trams that managed to City introduced models with lower floors countries use the term LRT differently, remain in operation in Japan when most about 350 mm over the rail head. Since making it hard for Japanese to understand cities were tearing up tram tracks are tram platforms are generally between 200 exactly what kind of urban transit system generally seen as vestiges of the past. and 300 mm higher than the road level, LRT is. Consequently, when LRT proponents talk low-floor carriages almost eliminate the The term LRT was first coined in the USA about the advantages of LRT systems, they step when boarding and exiting, which in the early 1970s as an attempt to emphasize the differences from tram provides nearly barrier-free access for revitalize the image of tramways, which systems, stressing the modern rolling everybody and permits faster schedule were seen negatively as an out-of-date stock, track and operating systems. speeds. Passengers have always system not fulfilling the needs of modern Despite this, LRT systems and trams look complained about high steps right from the urban transit. When tramcars share the similar, making it difficult for most people first days of trams but the early 660-mm right of way with motor vehicles, their to appreciate the differences. diameter wheels made low floors difficult transit potential is limited by traffic jams New LRT systems in Europe and North to achieve until today. and competition for space. This fact America are following government New York began operating partial low- indicated that LRT systems should guidelines to promote a modal shift from floor trams as early as 1912. They were basically have their own right of way to motor vehicles to a mix of pedestrian and called stepless or hobble skirt cars support faster operations. public transit, creating environment- (because women in hobble skirts, which The European and North American friendly and sustainable development. In were very narrow below the knees, could definition of LRT has tended to focus on these regions, LRT systems are seen as a board and disembark with ease). The mid- 30 Japan Railway & Transport Review 38 • March 2004 Copyright © 2004 EJRCF. All rights reserved. Stuttgart LRT on own right of way (Author) Strasbourg LRT sharing road with motor vehicles (Author) section of the car had a door leading to a The next step was to develop stub axles drive made it possible to extend the low- low floor with the bogies at the two ends. for the trailing bogies and small-diameter floor space over the powered bogie with Similar tramcars ran in the Los Angeles wheels, allowing the low floor to cover the wheels extending inside the car under suburbs and elsewhere in the USA, with about 70% of the carriage floor area (70% the seats. Single-axle bogies were also 176 manufactured for New York. A non- LF-LRV). Completely flat floors developed to reduce the number of motorized version was built in Europe in throughout the cars (100% LF-LRV) were wheels, thereby opening up more low- the 1920s and was pulled by the motorized finally achieved by developing floor space. To obtain a wide aisle over cars in a number of German cities. independently powered bogie wheels the bogie sections, the bogies are Today’s LF-LRVs use modern motor located under the seats (Fig. 1). anchored to the articulated bodies so that technologies to cut floor heights to Advances in semiconductor technology they barely rotate on curved track. between 300 and 350 m. Switzerland was reduced the size of conventional under- The 70% LF-LRV began operating about the first country with genuine low-floor floor control devices as well the need for 15 years ago followed by the 100% LF- cars in the mid-1980s. During the same regular maintenance, contributing to LRV a few years later. In 2003, there were time frame, LRT systems were beginning repositioning. Variable voltage variable more than 4000 low-floor tram sets in to contribute to urban renewal in the USA; frequency (VVVF) inverter control operation worldwide. Although this figure Germany and elsewhere started transformed the old heavy traction motor includes units with a low-floor area of no segregating trams from road traffic and into a small, light, three-phase induction more than 10%, about one-third are 100% even moved some tracks underground. motor, eliminating the need for bogie LF-LRVs (Table 1). While these improvements helped boost mounting. Insulated gate bipolar mode Due to structural limits, 70% LF-LRVs with the role of trams in urban transit it was transistors (IGBTs) also made inverters conventional bogies must have interior the appearance of low-floor cars that smaller and more efficient, permitting steps, but small traction motors make it greatly increased the appeal as people smaller control and other devices. possible to lower the floor near the bogies realized that the almost street-level access Resistors, batteries and other equipment to less than 600 mm. Thus, some 70% was very pedestrian friendly. Many cities used by regenerative braking as well as LF-LRVs have only one step that that had torn up their tram tracks decades auxiliary power units have been unitized passengers can easily negotiate. Unlike earlier began building LRT tracks as part and mounted on the car roof. In addition, in Japan, fare collection in Europe does of their urban renewal plans, and cities air brake equipment such as compressors not involve movement through the car that still had old tramways began was eliminated by use of electric between separate entrance and exit doors, upgrading based on LRT concepts. command braking with a spring-activated so European tram operators do not hydraulic release mechanism. necessarily require 100% LF-LRVs. Some New technologies Introduction of axle-less bogies opened operators prefer cars with conventional, Development of new LF-LRV technologies up the space usually occupied by the long highly reliable powered bogies and drive has focused on changing the location and wheel axles to increase the low-floor area. mechanisms, or cheaper vehicles, so these configuration of bogies and under-floor In the early cars, only the non-motorized are still being manufactured. equipment to achieve a low, flat floor. trailing bogies were axle-less but later Different models of 100% LF-LRVs have Early developments moved under-floor 100% LF-LRV designs moved the traction been developed as prototypes and some equipment to the roof or inside the car.