英语翻译Metro Signaling and Modern Railway Signaling Signaling used on high density metro (or subway) routes is based on the same principles as main line signaling.The line is divided into blocks and each block is protected by a signal but,for me

英语翻译Metro Signaling and Modern Railway Signaling Signaling used on high density metro (or subway) routes is based on the same principles as main line signaling.The line is divided into blocks and each block is protected by a signal but,for me
英语翻译
Metro Signaling and Modern Railway Signaling
Signaling used on high density metro (or subway) routes is based on the same principles as main line signaling.The line is divided into blocks and each block is protected by a signal but,for metro,the blocks are shorter so that the number of trains using the line can be increased.At first,metro signaling was based on the simple 2-aspect (red/green) system as shown in Diagram 8.Speeds are not high so three-aspect signals were not necessary and yellow signals were merely put in as repeaters where sighting was restricted.
Many metro routes are in tunnels and it has long been the practices of some operators to provide a form of enforcement of signal observation by installing additional equipment.This became known as automatic train protection (ATP).It can be either mechanical or electronic.
Electronic ATP includes tract to train transmission of signal aspects and (sometimes) their associated speed limits.On-board equipment will check the train’s actual speed against the allowed speed and will slow or stop the train if any section is entered at more than the allowed speed.
The Overlap
If a line is equipped with a simple ATP which automatically stops a train if it passes a red signal,it will not prevent a collision with a train in front if this train is standing right beyond the signal.There must be room for the train to break to a stop.This is known as a “safe braking distance” and space is provided beyond each signal to accommodate it.In fact,the signal is placed in rear of the entrance to the block and the distance between it and the block is called the “overlap”.Signal overlaps are calculated to allow for the safe braking distance of the trains using this route.Certainly lengths vary according to the site; gradient,maximum train speed and train brake capacity are all used in the calculation.
Diagram 2 shows the arrangement of signals on a metro where signals are equipped with trainstops (mechanical ATP) and each signal has an overlap whose length is calculated on the safe braking distance for that location.Signals are placed a safe braking distance before the entrances to blocks.

英语翻译Metro Signaling and Modern Railway Signaling Signaling used on high density metro (or subway) routes is based on the same principles as main line signaling.The line is divided into blocks and each block is protected by a signal but,for me
地铁信号和现代铁路信号
应用于高密度的地下铁道（或者说地铁）的信号是基于和主干道信号一样的理论的.线路被分成几块而每一块由一个信号保护.但是,对地铁来说,区块之间的距离更短以使得使用这条线路的列车数量得以增加.
最初,地铁信号是基于一个简单的双色（红和绿）系统的,正如在图表8上所展示的.因为速度并不高所以三色的系统并不是必须的.而黄色的信号仅仅是在那些视线不好的地方作为中继器使用.
许多的地铁轨道都是在隧道里的,而一些操作者已经花了很长时间实践来通过安装辅助装备提供一种信号观察的强制模式.这就是后来所说的“自动轮系保护”（ATP）.它既能是机械的也能是电子的.
电子的ATP包括一个向车发送信号标志的管道,有时也可以发送有关的速度限制.列车上的装备将检测列车的实际速度与限速要求并当车在超过限速是减慢或者停下它.
交迭
当一条装有简单的ATP系统的线路能够自动地在列车穿过红色信号时停下它时,它并不能防止列车与正停在信号的那一边的列车相撞.必须要有一段空间给列车来制动和停止.这就是所谓的“安全制动距离”.在信号的两边都留出了空间来满足这个要求.事实上,这个信号是放在一个区块的入口之后,而在它和区块之间的距离就被称为“交迭”.信号交迭被计算好来保证在这条线路中列车制动所需要的安全制动距离.当然,根据地点的不同长度也是不同的：倾斜度、列车的最大速度和列车的制动能力都被纳入计算当中.
图表2展示了一个装备机械ATP信号的线路中信号的安排.没一个信号都有一个根据地点计算的安全制动距离长度的交迭.信号被放在一个进入区块之前的安全制动距离上.