强者来翻译,看看你水平（勿用网络翻译工具等）On most modern railways, detection of the train’s position on the line and signal changing are done automatically and colored-light signals have largely taken the place of mechanical o

强者来翻译,看看你水平（勿用网络翻译工具等）On most modern railways, detection of the train’s position on the line and signal changing are done automatically and colored-light signals have largely taken the place of mechanical o
强者来翻译,看看你水平（勿用网络翻译工具等）
On most modern railways, detection of the train’s position on the line and signal changing are done automatically and colored-light signals have largely taken the place of mechanical ones.
The light signals usually mean:
Green: proceed at line speed.
Yellow: warning-the next signal is at red.
RRailway signaling differs from the traffic lights used on roads in that trains cannot stop quickly; for example, a train traveling at 160 km/h (100 mile/h) would need several kilometers to stop. Therefore on a railway, train need to be given advanced warning of a red stop signal so that they can slow down to a speed where they can stop quickly (a yellow signal). Put another way, yellow signals usually do not indicate an impending change to a red signal at the same location. Rather, a yellow signal gives a train advance warning that the following signal will be red.
To achieve this, the railway is divided into “blocks”, where blocks are stretches of track between two signals. Trains are automatically detected when they enter a block, which is done by what is known as a “track circuit”.
When calculating the size of the blocks and hence the spacing between the signals, the following has to be considered: line speed (the maximum speed the train is allowed to travel); gradient (to compensate for the assistance or otherwise afforded to deceleration); sighting (the ability of the driver to see the signal); reaction time (of the driver).
The track at either end of the block is electrically insulated, and within the block a small electrical current passes though the track. When a train passes a signal and enters a block, the metal wheels and axle of the train short-circuit the current, which causes a relay association with the track circuit to itself become de-energized.
When the relay is de-energized, the signal which the train has just passed automatically turns from green to red, the signal behind that one automatically turns yellow, and the signals behind that one can remain green.
ed: stop.

强者来翻译,看看你水平（勿用网络翻译工具等）On most modern railways, detection of the train’s position on the line and signal changing are done automatically and colored-light signals have largely taken the place of mechanical o
手工翻译,如下,仅供参考：
多数现代铁路系统都采用自动方式和有色灯信号检测火车在线位置及信号改变,以取代传统的机械方式.
一般,信号灯的含义如下：
绿色: 继续保持线速
黄色:提示可能出现红色警告信号
铁路信号不同于马路上的红绿灯,因为火车无法快速停下：如, 一辆行驶速度在160 km/h (100 mile/h)的火车需要滑行数公里才能停止.因此在铁道上,需要有红色信号灯警告信号提醒火车必须减速到适合快速停止的速度（黄色信号等）.再如, 在同一处,黄灯未必一定表示紧接着就是红灯.而是警告火车不要招红灯.为此, 铁路被分为多个连续的“区”,每段就是以两个信号灯之间的铁轨的拓展.火车进入某个区时,将自动受到检测,进行检测的是一个所谓的“轨道电路”.
当计算区大小和信号间“阶速”时,需考虑到些列情况: 线速(所允许的最大火车速度); 倾斜度 (补偿协助或可以减速); 可视性 (火车司机能看到信号的能力); 反应时间(司机).
在区任何一端的轨道都是电绝缘的,在区内有微电流通轨道. 当火车通过信号灯后进入某区时, 金属轮和火车车轴将微电流短路, 从而将轨道电路中的继电器电流切断.当继电器电流被切断后, 火车刚通过的信号立即自动由绿色变为红色,继而变成黄色,继而又回到绿色 .
最后,火车停下.