教材1 Microsoft Word 文档
98 Lesson 19 Railway Signling（铁道信号）
Railway signaling is a safety system used on railways to prevent trains from colliding. Trains are uniquely susceptible to collision because of running on fixed rails. They are not capable of avoiding a collision by steering away, and as can a road vehicle; ~ furthermore, trains cannot decelerate rapidly, and are frequently operating at speeds where by the time the driver can see an obstacle, the train cannot stop in time to avoid colliding with it.
Most forms of train control involve messages being passed from those in charge of the raft network or portions of it to the train crew; these are known as " signals" and from this the topic of train control is known as "signaling"
Timetable and train order operation has some significant flaws, such as an over-reliance on the ability of the crew of a stranded train to let other trains know of the problem, and a general intolerance for human error. When everything goes perfectly, it works well, but mistakes are easy and deadly.
Timetable or train order is only suitable for railway lines which carry relatively little traffic, and is unworkable on busy rail lines, because it requires great separation between trains. Where this is the case, physical signals need to be used to show the train crew whether the line ahead is occupied and to ensure that sufficient space is kept between trains to allow them to stop.2
If two trains can't be running on the same section of track at the same time, then they cannot collide. This notion forms the basis of most signaling systems.
The rail network is divided into sections, known as blocks. Two trains are not allowed to be in the same block at the same time. A train cannot enter a block until it is permitted, generally by a signal that the block ahead is empty.
On high-speed railways, block signaling has disadvantages.Because the required block length to safely stop a train would severely decrease the line's capacity. Also, signals become increasingly hard to spot and recognize at higher speeds. Several cab signaling systems have been developed to overcome those disadvantages. The European Train Control System will feature moving blocks that allow trains to follow each other at exact braking distance. Historically, some lines operated rules, where certain large high speed trains were signaled under different rules and only given the right of way if two blocks in front of the train were clear.3
There are two distinct forms of block signaling. Absolute block signaling is operated in a manner designed to ensure two trains may not occupy the same block at once. Telegraph codes are used to communicate between signal boxes, each of which controls a block. The signalman only allows entry to a given block, when no train occupies the block. When the train traverses the block, the signalman signals ahead to the next block who will accept the train if they have space or delay it otherwise. As
an additional safety check all trains have a tail lamp.4 If no tail lamp is seen, the signalman assumes his block is not empty, after the train has passed. As the lack of a tail lamp may indicate the train has come apart. Instead the block remains occupied and the signalman telegraphs the next signal box to halt the train and investigate.
In a permissive block system, trains are permitted to pass signals indicating the line ahead is occupied, but only to do so in a manner where they can stop safely driving by sight.5 This allows improved efficiency in some situations and is mostly used in the USA.
An absolute block system is itself not entirely absolute. Multiple trains may enter a block, given specific authorization. This is necessary in order to join trains together, split trains, rescue failed trains and the like. The signalman in giving authorization also ensures the driver knows precisely what to expect ahead, and the driver must operate the train in a safe manner considering this information.
NewWordSand EXpressions
Collide 碰撞
susceptible 易受感动的，敏感的
avoid 避免，消除
steer 指导，驾驶
decelerate 减速
in charge of 负责
timetable 时间表
over-reliance 过度信赖·
flaw 缺点，缺陷
stranded 束手无策的，进退两难的
intolerance n．不容忍
error n．误差，过失，错误
deadly adj．致命的，极度的，必定的
relatively adv．相关地
unworkable adj 难运转的，不能实行的
separation n．分离，分开
occupy vt 占用，占领，占据
section n．区
notion n．概念，观念，想法，主张·
divide v 划分，分开，隔开
ensure vt 保证，担保
spot n．认出，发现
block n 区间，闭塞
disadvantage n．不利，劣势
severely adv．严格地，激烈地
decrease vi vt 减少
overcome vt 战胜，克服，征服
distinct adj 清楚的，明显的，独特的
telegraph v发电报，打电报说
code n．代码，代号，编码
communicate v 沟通，通信，传达
indicate vt指出，显示，象征，预示
halt vt 使停止，使立定
permissive adj 许可的
entirely adc．完全地，全然地，一概地
multiple adj 多样的，多重的，倍数，若干，成倍增加authorization n．授权，认可
traverse v 横过
be capable of 能够
NoteS to the TeKt
1．Trains areuniquely susceptible to collisiOn because，running on fixed rails；they aren not capable of Avoiding a collision by steering away，and as can a road vehicle．
译文列车运行在固定铁轨上，对碰撞特别敏感。它们不能像路上的车辆那样避开碰撞。2．Where this is the case，physical signals need to be used to show the train crew whether the line
Ahead is occupied and to ensure出atsumcientspaceiskeptbetweentrainstOaUOWthemtOstop．
囤日国在此情况下，需用物理信号来显示前方线路是否有车占用，并确保列车间有足够间BE
以允许停车。
3．HistoricatlV，someUnesoperatedmles，wherecertainlargehighspeedtrainsweresignaledunder differentmlesandOnlygiven出edghtOfway证twOblOcksinfrontOfthetrainwereclear．
圉日日历史上，某些线路按规章运行，在这些线路上，某些大型高速列车在不同的规章下发
信号，并且，如果列车运行前方的两个区间开通，列车就会让出右车道。4．AsanadditiOnalsafetycheckall仕8inshavea曲1lamp．
该句为一倒装句。正确顺序为：A11trainshaveatdllampasanadditionalsafetycheck．
5．In a permissive block system，仕ains are permitted tO pass signals血dicating the Une ahead is
OCC即ied，butOnlytOdOSOinamannerwhere01eycallStOpsafelydrivingbysi2hL
田日田在一个容许闭塞系统中，允许列车传送信号以显示前方线路有车占用，但仅当通过视
觉能够判断列车能安全停靠时才采用这一方式。
EXerCiSeStOtheTeKt
I TranslatethefOUowingtermsintoChinese．
(1)railwaysisnaling (2) raUnetwork (3) busyrailUne
(4)physicalsignal (5)b10cksi吕naling (6)cabSi吕nalingsystems
(7)movingblOck (8)b1-akingdistance (9)abs01utebhcksignaling
(10)Signalboxes
ⅡDeddewhethereachOfthefOUOWingstatementsistrueOrfalsellccordingtOthetexL
(1)丁ralnSareC叩ableOfavoidingaCOUiSiOnbysteeringaway．( )
(2)Atraincan'tenterablOckundl让ispei-mitted．( )
(3)Thereare出teedisdncrfOFillsOfblOcksignaling．( )
(4) EachsignalbOxcontr01sablOck．( ) ·
(5)Anabs01uteblOcksystemisentirelyabs01ute．( )
ⅢAnswerthefOUOWingquesUOIlSaccordingtO中etext．
(1)HowtOdehneblOck?
(2) WhatdisadvantageShaSblOckSignalingOnhigh·speedrallways?
(3)Whatis出eba蛆sOfmostSignaling?
(4) WhenaretrainspernliUedtOpasssiZn日1inapermissiVeblOckSystem‘：
(5)WhatSiZninCantnawsdOtimetableOrtrainOrderoperatiOnhave?
reading material
The Development of Railway Signal
In the very early days of railways, on double-tracked railway lines, where trains traveled in one direction on the same stretch of track, a means was needed to space out the trains to ensure that they did not collide, In the very early days of railways, men were employed to stand next to the line at certain intervals with a stop watch, these men used hand signals to signal to train drivers that a preceding train had passed more or less than a certain number of minutes ago, this was called "time interval working' . If a train had passed the man only a short while ago, the following train was expected to slow down or stop to allow sufficient space to develop between the trains, to prevent a collision.
This system was flawed, however, as the watchman had no way of knowing whether the preceding train had cleared the tracks ahead. And so if the preceding train broke down or stopped for some reason, the following train would have no way of knowing, and collide with it rear-on. Accidents of this type were common in the early days of railways. However, with the invention of
the electrical telegraph, it became possible for the station or signal box ahead to send message
back to confirm that a train had passed and that the line ahead was clear~ this was called the "block system" .
Mechanical semaphore signals replaced hand signals in the early 1840s. When the all-clear message was received, a signalman in a signal box would pull a lever which would move the signal into the all-clear position. This required the placing of signal boxes at regular intervals along the line.
The block system came into use gradually during the 1850s and 1860s but became mandatory in the United Kingdom after parliament passed legislation in 1889 as a response to numerous railway accidents. This required block signaling for passenger railways, along with interlocking and most of the practices still required and used today. Similar legislation was passed by the United States around the .same period.
New Words and Expressions
double-tracked 双轨的
stretch．一段时间，一段路程，伸展
spaceout 留间隔，把……拉开距离
interval 间隔，距离，幕间休息，时间间隔
precedingtrain先行列车
thefollowingtrain 后行列车
semaphoresignals 臂板信号
Exercises to the Material
Answer the following questions according to the material.
( 1 ) How to space out the trains to ensure that they did not collide in the very early day of railways ?
2) Why did it become possible for the station or signal box ahead to send a message back to
confirm that a tram had passed and that the line ahead was clear?
(3) When did mechanical semaphore signals replace hand signals ?
(4) When did the block system come into use gradually?
(5) Where did the block system become mandatory ?
Lesson20 C1aSSmCaUOnYard(铁路编组场)
Classification yard or marshalling yard (including hump yards) is a railroad yard found at some freight train stations, used to separate railroad cars on to one of several tracks.~ First the cars are taken to a track, sometimes called a lead or a drill. From there the cars are sent through a series of switches called a ladder onto the classification tracks. Larger yards tend to put the lead on an artificially built hill called a hump to use the force of gravity to propel the cars through the ladder.
Freight trains which consist of isolated cars must be made into trains and divided according to their destinations. Thus the cars must be shunted several times along their route in contrast to a unit ~ train, which carries, for example, automobiles from the plant to a port, or coal from a mine to the power plant.2 This shunting is done partly at the starting and final destinations and partly (for
long-distance-hauling) in classification yards.
There are three types of classification yards: fiat-shunted yards, hump yards and gravity yards.
Flat-shunted yards
Here, the tracks lead into a flat shunting neck at one or both ends of the yard where the cars are pushed to sort them into the right track. There are many medium-sized flat yards in the USA and also some which are quite large.
In Europe several major classification yards in Italy have never had a hump; other large European flat yards are an incompleted yard with 32 tracks which was planned to be a hump yard but has no hump.3 In Argentina all classification yards with the exception of Villa Mafia are flat yards, though some of them have approx. 30 or more tracks.
Hump yards
These are the largest and most effective classification yards with the largest shunting capacity -- often several thousand cars a day. The heart of these yards is the hump: a lead track on a hill (hump) over which the cars are pushed by the engine. Single cars, or some coupled cars in a block, are uncoupled just before or at the crest of the hump and roll by gravity into their destination tracks in the classification bowl (the tracks where the cars are sorted) .
The speed of the cars rolling down from the hump into the classification bowl must be regulated because of the different natural speed of the wagons (full or empty' heavy or light freight, number of axles) , the different filling of the tracks (whether there are presently few or many cars on it) and different weather conditions ( temperature, wind speed and direction) .4 As concerns speed regulation
there are two types of hump yards.- without or with mechanisation by retarders. In the old non-retarder yards braking was usually done in Europe by railroaders who lay skates onto the tracks, or in the USA by riders on the cars. In the modem retarder yards this work is done by mechanized "rail brakes" called retarders. They are operated either pneumatically or hydraulically.
Classification bowls consist of in average 20 to 40 tracks divided into several fans or balloons of tracks, in Europe usually with eight classification tracks following a retarder in each one, often 32 tracks altogether. In the USA also many classification bowls have more than 40 tracks up to 72 which there are often divided into six to ten tracks in each balloon loop, compared with eight in Europe.
The world's largest classification yard is a hump yard, all important classification yards are hmnp yards. Most hump yards are single yards with one classification bowl but some, mostly very large, hump yards have two of them, one for each direction, thus are double yards.
However, due to the transfer of freight transport from rail to road and the containerization of rail freight transport for economical reasons, hump yards are generally in decline. In Great Britain, Denmark, Norway, Japan and Australia, for example, all hump yards have already been closed.
Gravity yards
These are operated similarly to hump yards but in contrast to the latter, the whole yard is setup on a continuous falling gradient and there is less use of shunting engines. Typical locations of gravity yards are places where it was difficult to build a hump yard due to the topographyfi Most gravity yards were built in Germany and Great Britain, sometimes also in some other European countries. Ia the USA there were only very few old gravity yards: none seem to be in operation today. The largest active gravity yard is Nuremberg classification yard, Germany. Gravity yards also have a very large capacity but they need more staff than hump yards and thus they are thc most uneconomical classification yards.
New Words and Expressions
classificationyard铁路编组场
marshallingyard铁路货运编组站’
humpyard驼峰调车场
shunt 逃避
flat-shuntedyard平面调车场‘
gravityyard重力调车场
shuntingcapacity调车容量
retarder．阻滞剂，缓凝剂，减速器
Skate n．冰鞋
Balloon n．气球
fallinggradient下坡道’
shuntingengine调车机车
Notes to the Text
1．A classification yard Or a marshalling yard(including hump yards)is a railroad yard f ound at some Freight train stations，used tO separate railroad cars onto one Of several tracks．
译文：铁路编组场或铁路货运编组站(包括驼峰调车场)设置在一些铁路货运站的铁路站场，
用于解体火车车厢至几条轨道中的某一条。
、2．Thus the Cars must be shunted several times along their route in contrast tO a unit train，which cames，forexample，automobilesfromtheplanttOaport，OrcoalfromaminetOthepowerplant．译文：因而，与从工厂运送汽车至码头或从矿区运送煤炭至发电厂的单元列车相比，车厢必须沿途进行好几次调车进路。
3．Other large European flat yard are an incompleted yard with 32 tracks which was planned tO be a Hump yard but has no hump．
译文：其他欧洲大型平面调车场是不完善的调车场，拥有32条轨道，设计了驼峰调车场但
并无驼峰。
4．The speed Ofthe cars rolling downf rom the hump into the classification bowl must be regulated Because Of the different natural speed Of the wagons (full Or empty，heavy Or light freight，number Of axles)，the different filling Of the tracks (whether there are presently few Or many Cars On it) And different weather conditions (temperature，wind speed and direction)．
译文：根据货车不同的正常速度(空载或满载的，重型或轻型货物以及轮轴数量)、不同的
轨道填充物(不论目前是否有车辆在上面)及不同的天气情况(温度、风速及方向)，列车
从驼峰至编组场底部的溜放速度必须调节。
5．Typical locations Of gravity yards are places where it was difficult tO build a hump yard due tO the topography．
译文：典型的重力调车场通常设置在那些由于地形很难修建驼峰调车场的地方。
Exercises to the Text
'I Decide whether each of the following statements is true or false according to the text.
( 1 ) Larger yards have a hump to use the force of gravity to propel the cars through the ladder.
( )
(2) There are 32 tracks in some large European flat yards. ( )
(3) All important classification yards are gravity yards. ( )
(4) Some of hump yard have two classification bowls. ( )
(5) Shunting engines are used in gravity yards. ( )
II Answer the following questions according to the text.
( 1 ) What is a classification yard?
(2) What types of classification yards are there ?
(3) What is the heart of hump yards?
(4) The speed of the cars rolling down from the hump into the classification bowl must be
regulated, Why ?
(5) What is the world's largest classification yard ?
Reading material
Marshalling Yards
Marshalling yards were functionally the junctions in the railway goods services. It was in the marshaling yard that a train arriving from one route would be broken up and the stock added to rakes being put together for the final destination. They were located at railway junctions and on the periphery of large 'industrial areas and smaller yards were provided where several branch lines converged onto a main line route.
Each of the railway companies operated their own marshaling yards and all of these were inherited by the nationalised system. As recently as 1963, there were some six hundred marshalling yards still in use, with capacities ranging from a few hundred wagons to a few thousand. By 1982 there were only fifty nine marshaling yards in operation on the whole of the British Railways system.
Operating a hump yard involved three men at the crest of the hump, one man keeping track of the wagons, a shunter who uncoupled the wagons at the top of the hump and a man who applied the hand brake so the wagon would not roll too quickly down the sidings. The points were controlled from a central signal box, but this system still required men to mn alongside the wagons and apply the hand brakes in the sidings with the consequent risk of injury. One way to reduce the risk to staff was to supply chocks that could be placed on the track to stop a wagon but these sometimes derailed the wagons.
New Words and Expressions
Rake n. 粑子，斜度，向船尾的倾斜，放荡者
Periphery n. 外围，边缘
Converge vi. 会于一点，向一点会合，（趋于）或相同
Inherit vt. 继承，遗传而得
Crest n. 扳道员，能干的组织者
Uncouple vt. 解开，分开
Siding n. 铁路的侧线，旁轨
Exercise to the Material
Answer the following questions according to the material.
( 1 ) Where would a train arriving from one route be broken up?
(2) Where were marshalling yards located ?
(3) How many marshalling yards in use are there, as recently as 19637
(4) How many people did operating a hump yard involve ?
(5) How to reduce the risk to staff?