1、10. Rail Transit Engineering 10.1 Text10.1.1 PassageLight RailLight rail or light rail transit (LRT) is a particular class of urban and suburban passenger railway that uses equipment and infrastructure that is generally less massive than that used for rapid transit systems, with modern light rail ve
2、hicles usually running along the system.轻轨或轻轨交通是一类特殊的城市和郊区铁路客运，其设备和基础设施规模一般小于快速公交系统，和现代轻轨车辆通常使用同一系统。Light rail is the successor term to streetcar, trolley and tram in many locales, although the term is most consistently applied to modern tram or trolley operations employing features more generally a
3、ssociated with metro or subway operations, including exclusive rights-of-way, multiple unit train configuration and signal control of operations. 轻轨是继有轨电车和电车后出现的，虽然这个术语始终一贯地应用于现代有轨电车，其使用特点通常与地下铁道或地铁有很多关联，包括独立路权，多单元列车配置和信号控制操作系统。The term “light rail” is derived from the British English term “light ra
4、ilway” long used to distinguish tram operations from steam railway lines, and also from its usually lighter infrastructure.“轻轨”这个术语来源于英语“轻型铁路”，长期用于区分电车操作和蒸汽驱动铁路，也把电车从较轻的基础设施中区分开来。Light rail systems are almost universally operated by electricity delivered through overhead lines, though several system
5、s are powered through different means, such as the JFK Air Train, which uses a standard third for its electrical power, and tram in Bordeaux which use a special third-rail configuration in which the rail is only powered while a tram is on top of it. A few unusual systems like the River Line in New J
6、ersey and the O-Train in Ottawa use diesel-powered trains, though this is sometimes intended as an interim measure until the funds to install electric power become available.轻轨系统几乎普遍通过架空线用电力驱动，虽然多个系统通过不同方式提供动力，如肯尼迪空中列车（肯尼迪国际机场捷运），采用了三级标准电力，波士顿的有轨电车使用了特殊的三轨构造，当电车在上面时轨道才会提供动力。有一些不常见的系统采用柴油动力火车，如新泽西州的瑞
7、夫线和渥太华的 O 列车，不过有时这只是资金到位以安装电力系统的临时措施。1. History of the light rail From the mid-19th century, horse-drawn trams (or horse cars) were used in many cities around the world. In the late 1880s electrically-powered street railways became technically feasible after the invention of a trolley system of coll
8、ecting current by American inventor Frank J. Sprague who installed the first successful system at Richmond, Virginia. They became popular because roads were then poorly surfaced, and before the invention of the internal combustion engine and the advent of motorbuses, they were the only practical mea
9、ns of public transport around cities.19 世纪中期，世界上的一些城市出现了马拉的车厢（或马车） 。在 19 世纪 80 年代后期，美国发明家弗兰克.斯普拉格发明了收集电流的有轨电车系统，电动路面铁路在技术上成为可能，他在弗吉尼亚的里士满成功安装了第一个有轨电车系统。电车受到欢迎是因为那时路面很差，在发明内燃机和公共汽车出现之前，电车是城市唯一实用的公共交通工具。The light rail systems built in the 19th and early 20th centuries generally only ran in single-car
10、setups. Some rail lines experimented with multiple unit configurations, where streetcars were joined together to make short trains, but this didnt become common until later. When lines were built over longer distances (typically with a single track) before good roads were common, they were usually c
11、alled interurban streetcars in North America or radial railways in Ontario.19 世纪和 20 世纪早期建立的轻轨系统通常是单车设置。一些铁路线尝试使用多节配置，电车被连接到一起形成短列车，但这直到后来也没有普及。在好的路况普及前，已经建成了较长的线路，通常北美洲称为市际电车，安大略称为放射状铁路。In North America, many of these original light-rail systems were decommissioned in the 1950s and onward as the po
12、pularity of the automobile increased. Though some traditional trolley or tram systems still exist to this day, the term “light rail” has come to mean a different type of rail system. Beginning in the 1980s, some citied began reintroducing light-rail systems that more like subway or metro systems tha
13、t operate at street level. These light-rail systems include modern, multi-car trains that can only be reached at stations that spaced anywhere from a couple blocks to a mile or more apart. Some of these systems operate within roadways alongside automobile traffic, and others operate on their own sep
14、arate right-of-way.在北美洲二十世纪五十年代及以后，因为汽车的增加及普及，许多原始的轻轨系统退役了。虽然现在一些传统的电车或有轨电车系统依然存在，“轻轨”这个词已经意味着不同类型的轨道系统。二十世纪 80 年代开始，一些城市开始重新引进轻轨系统，这些系统在运作上已经比较接近地面运行的地铁系统。这些拥有现代化的多节车厢的轻轨系统，只在车站停车，车站的间隔距离是从几个街区到一英里或更长距离。一些系统在路面上与机动车车道并行，另外的则有它们的专有路权（有自己的路线）。 As with other rail systems, the rail gauge has had a lot
15、of variations, but today standard gauge is dominant. Narrow gauge was common in many earlier systems, though as systems merged or died out, old lines were often upgraded, removed, or replaced. Some systems still use other track gauges, however.和其他轨道系统一样，轨距有许多变化，但是现在标准轨距成为主导。窄轨在许多早期系统是常见的，虽然随着系统合并或撤销
16、，老线路常常被升级、取消，或替代，然而一些系统仍旧在使用其他轨距。2. Definition Most rail technologies, including high-speed, freight, commuter /regional, and metro/subway are considered to be “heavy rail” in comparison. A few systems such as people movers and personal rapid transit could be considered as even “lighter”, at least i
17、n terms of how many passengers are moved per vehicle and the speed at which they travel. Monorails are also considered to be a separate technology. Light rail systems can handle steeper inclines than heavy rail, and curves sharp enough to fit within street intersections. They are generally built in
18、urban areas, providing frequent service with small, light trains or single cars.大部分轨道技术，包括高速列车，货运列车，通勤列车，地铁等相比之下被认为是“重轨”。少数一些系统如大众运输工具和快速客运，在每辆车运载乘客量和速度的条件下，可以被认为是“轻轨”。单轨铁路也被认为是一项独立的技术。轻轨系统可以处理比重轨更陡峭的斜坡，并且曲面半径足够小以适应交叉的街道。他们一般建立在城市地区，常应用于小的、轻的列车或单一车厢。The most difficult distinction to draw is that bet
19、ween light rail and streetcar or tram systems. There is a significant amount of overlap between the technologies, and it is usual to classify streetcar/trams as a subtype of light rail instead of as a distinct type of transportation. The two common versions are:最难区分的是轻轨和有轨电车和电车系统之间的区别。在技术上它们有相当多的重叠部
20、分，通常把有轨电车作为轻轨的一个分支，而不是另一种运输类型。两个常见的版本是：(1) The traditional type, where the tracks and trains run along the streets and share space with road traffic. Stops tend to be very frequent, but little effort is made to set up special station. Because space is shared, the tracks are not usually visible. （1）传
21、统类型：轨道系统列车与路面交通混行。停车频繁，但是很少有人努力设立特定的车站。因为空间是共享的，轨道通常不可见。(2) A more modern variation, where the trains tend to run along their own right-of-way and are often separated from road traffic. Stops are usually less frequent, and the vehicles are often got on from a platform. Tracks are highly visible, and
22、 in some cases significant effort is used to keep traffic away through the use of special signaling and even grade crossings with gate arms. At the highest degree of separation, it can be difficult to draw the line between light rail and metros, as in the case of Londons Docklands Light Railway, whi
23、ch would likely not be considered “light” compared with London Underground 地铁.（2）一个更现代化的变化，是列车趋向于与道路交通分开，沿着专有轨道运行。停车通常不再那么频繁，通常从站台上车。轨道非常明显，在某些情况下，人们尽很大的努力来保持列车离站时使用特殊的信号，甚至交叉道口设有门臂。在最大程度的分离后，可能很难区分轻轨和地下铁路，比如伦敦码头区轻便铁路，与伦敦地铁相比，可能就不会被认为“轻”了。Many light rail systems have a combination of the two, with b
24、oth on road and off road sections. In some countries, only the latter is described as light rail. In those places, tram running on mixed right of way are not regarded as light rail, but considered distinctly as streetcars or trams.许多轻轨系统是与道路混合行驶和与一般道路分离两部分的结合，在一些国家，只有后者被称为轻轨。在那些地方，以混合方式运行的电车不被认为是轻轨，
25、但无疑，地面电车或有轨电车是轻轨。Light rail is usually powered by electricity, generally by means of overhead wires, but sometimes by a live rail, also called third (a high voltage bar alongside the track), requiring safety measures and warning to the public not to touch it. In some cases, especially when initial f
26、unds are limited, diesel-powered versions have been used, but it is not a preferred option. Some systems, such as the JFK Air Train in New York City, are automatic without a driver; however, such systems are not what are usually thought of as light rail. Automatic operation is more common in smaller
27、 people mover systems than in light rail systems, where the possibility of grade crossings and street running make driverless operation of the latter inappropriate.轻轨通常由电力驱动，一般采用高架线，但是有时使用活动轨，也称为第三轨（高电压线杆旁的轨道），需要设置安全措施和警示牌防止民众触摸供电轨。在一些情况下，尤其在最初资金有限，以柴油为动力列车投入使用，轻轨并不是一个很好的选择。一些系统，如纽约市肯尼迪空中列车是全自动操作，毋需
28、司机。然而，这些系统并是通常认为的轻轨系统。比起轻轨系统，自动操作在较小的捷运（大众运输工具）系统中更加常见，因为在平面交叉口和街道运行中使用无人驾驶，轻轨系统是不合适的。3. Advantages of light rail Light rail systems are usually cheaper to build than heavy rail, since the infrastructure does not need to be considerable, and tunnels are usually not required as most metro systems. In
29、 addition, the ability to handle sharp curves and steep gradients can reduce the amount of work required.通常轻铁系统造价比重铁低，因为不需要大量基础设施，而且，像大多数地铁一样，一般不需要隧道。此外，轻铁系统有能力处理急转弯和陡坡，可大大减少工作量。 Traditional streetcar systems and also newer light rail systems are used in many cities around the world because they gen
30、erally can carry a larger number of people than any bus-based public transport system. They are also cleaner, quieter, more comfortable, and in many cases faster than buses. In an emergency, light rail trains are easier to evacuate than monorail or elevated rapid rail trains.世界上许多城市使用传统的电车系统，同时也使用新型
31、轻轨系统，因为它们通常可以承载比任何以公共汽车为基础的公共交通系统更多的人。它们也更清洁，更安静，更舒适，在很多情况下也比公共汽车更快。在紧急情况下，轻轨列车比单轨电车或高架快速列车更容易疏散群众。Many modern light rail projects re-use parts of old rail networks, such as abandoned industrial rail lines.许多现代轻轨项目重新使用部分旧轨道网络，如废弃的工业轨道线。4. Disadvantages of light rail Like all modes of rail transport,
32、 light rail tends to be safest when operating in dedicated right-of-way with complete grade separations. Nevertheless, grade separations are not always financially or physically feasible.像所有的轨道交通模式，随着轻轨路权的分级，最安全的是在专有通行线中运行的电车。然而，路权等级分离在经济上或物质上并不总是可行的。In California, the development of light rail syst
33、ems in Los Angeles and San Jose caused a high rate of collisions between automobiles and trolleys during the 1990s. The most common cause was that many senior citizens were unfamiliar with light rail trolleys and often mistook the trolley “T” signal lights for left-turn signal lights. They would the
34、n make a left turn, right into the path of a trolley. The same high crash rate problem existed when the METRO Rail was first set up in Houston, Texas.20 世纪 90 年代，在加利福尼亚的洛杉矶和圣何塞，轻轨系统的发展造成了汽车和电车之间的碰撞率很高。最常见的原因是，许多老年人不熟悉轻轨电车，经常把电车“T”信号灯当做左转信号灯。 然后左转弯，正好进入电车轨道。当德克萨斯州休斯顿的城市轨道交通成立之初，也存在同样的高事故率。To reduce s
35、uch collisions, brighter lights and louder warning klaxons have been added to many at-grade crossings. However, consequently, many people do not like to live next to light rail crossings because the noise makes them impossible to sleep. A more effective means of reducing or preventing automobile-lig
36、ht rail collisions has been the installation of quad crossing gates at gate crossings. Theses gates block both lanes of a street when the gate closes. These prevent those driving automobiles from driving around the gates when they are lowered.为了减少这些碰撞，许多路面交叉口添加了明亮的灯光和响亮的警告警笛。然而，因此，很多人不喜欢住在轻轨交叉口附近，因为
37、噪音使他们无法入睡。一个更有效减少或防止汽车和轻轨发生碰撞的方式是在闸门通道安装方形闸门。当闸门关闭时，能够阻止街道两边车道通行。这样可以防止闸门较低时，汽车会驶过闸门。Monorail supporters like to point out that light rail trolleys are heavier per pound of cargo carried than heavy rail cars or monorail cars, because they must be designed to avoid collisions with automobiles.单轨铁路的支持者指出，必须设计轻轨电车承载每磅负荷的轨重比重轨车或单轨列车要重，才能避免与汽车相撞。
