自动控制文献翻译——列车不允许在相同的时间占用同一轨道区段，这样就不会彼此相撞，所以铁路线被分割成几段称为闭塞分区。在正常情况下，同一时间内在同一个闭塞分区里只允许一列火车运行，这个规则是铁路安全制度的基础。

1闭塞信号的发展史

在双线铁路上，列车在线路上朝一个方向运行时，必须确保列车能保持足够远的距离而不相撞。早期的铁路，被雇佣的人们站在铁路线旁边的间隔处（闭塞）使用一块秒表和手信号通知驾驶员前方列车超过这列火车多长时间，这称为时间间隔法。如果前面的列车刚通过，为了留出更大的空间运行，那么下一列火车就被通知减速运行。

值班员没有办法知道列车是否出清了前面的区段，因此要是前面的列车由于非正常原因停下来，那后面列车的驾驶员除了很清楚的看到，而没有办法知道前面的列车已经停车。所以，早期的铁路经常发生意外行车事故。随着电子电报的发明，值班员可能在车站或信号楼里通过发送信息（通常是鸣响电铃）来确认列车已通过或出清特定的闭塞区段，这被称为闭塞系统。

2闭塞

下面介绍几种不同的闭塞系统。

2.1进入和离去人工控制的闭塞区段

在允许列车进入一个区段之前，信号人员必须确定该区段没有列车占用。当火车离开一个区段时，它必须通知信号人员控制其进入下一区段。即使信号人员收到前一列车已离开区段的通知，他通常需要联系下一信号楼来确定下一列车的到来。当列车到达闭塞区段的末端时，列车一般先于信号人员传送的信息到达，所以，信号人员必须要在最后一节车厢的后面看见列车的尾部标志，这样就保证了......

Trains cannot collide with each other if they are not permitted to occupy the same section of track at the same time, so railway lines are divided into sections known as blocks. In normal circumstances, only one train is permitted in each block at a time. This principle forms the basis of most railway safety systems.

1 History of block signalling

On double-tracked railway lines, which enabled trains to travel in one direction on each track, it was necessary to space trains far enough apart to ensure that they could not collide. In the very early days of railways, men were employed to stand at intervals ("blocks") along the line with a stopwatch and use hand signals to inform train drivers that a train had passed more or less than a certain number of minutes previously. This was called "time interval working". If a train had passed very recently, the following train was expected to slow down to allow more space to develop.

The watchmen had no way of knowing whether a train had cleared the line ahead, so if a preceding train stopped for any reason, the crew of a following train would have no way of knowing unless it was clearly visible. As a result, accidents were common in the early days of railways. With the invention of the electrical telegraph, it became possible for staff at a station or signal box to send a message (usually a ring on a bell) to confirm that a train had passed and that a specific block was clear. This was called the "block system".

2Block

There are three kinds of block system.

2.1 Entering and leaving a manually-controlled block

Before allowing a train to enter a block, a signalman must be certain that it is not already occupied. When a train leaves a block, he must inform the signalman controlling entry to the block. Even if the signalman receives advice that the previous train has left a block, he is usually required to seek permission from the next signal box to admit the next train. When a train arrives at the end of a block section, before the signalman sends the message that the train has arrived, he must be able to see the end-of-train......