Uk railway signalling

  3)What is Approach locking & Back locking with conditions ? Ans) * ROUTE HOLDING IS DONE BY APPROACH AND BACK LOCKING. Approach locking: It is an electrical locking which doesn’t allow us to alter the route when train entering into the station. For providing approach locking , a track circuit for a length of 1.2kms. Need to be provided. Provision of such a long track circuit for the purpose of approach locking is a costly proposition. Therefore, the approach locking is provided without the approach locking becoming effective the moment the signal is cleared irrespective of the position of the train in the approach.Such an approach locking is known as “Dead approach locking”. In other words, once the signal is „OFF it gets approach locked and the route can be released B ack/Route locking: It is an electrical locking ,whenever train passes the signal and it effective until the train occupies & clear the all tracks in route including last point section.The route...

4)Explain Route control chart /table of control /Selection table with each column? ANS) As it will be cumbersome to prepare the signaling circuits directly from the signal interlocking plan (SIP). The various safety aspects such as interlocking of conflicting routes, requirements of points for each route, the track circuit controls for the points, the route holding requirements such as approach locking and back or route locking and other controls such as crank handle controls, gate controls, block control and overlap release, etc. are first put in a table called “control table.” Or “selection table” and this table is used in the preparation of circuits. It specifies the routes on which the train can be travel without any collisions/derailments . An interlocking system implements this control table making sure that the running of trains in safe.   Control table for interlocking system in Indian Railways is done by a private companies like Siemens, kyosan,hitachi,medha servo etc....

The first railway semaphore signal was erected in 1841 at New Cross Gate by Charles H Gregory, Engineer of the London & Croydon Railway. During daylight hours, a semaphore signal conveys its indications by a pivoted 'arm'. The arm projects to the left of the post when viewed in the applicable direction of travel, and its angle determines the indication. The first semaphores were three-position signals, used in conjunction with the time interval system. The 'danger' indication was given by the arm being in the horizontal position  [2.1] . When in this position, a red light was shown at night. For the 'caution' indication, the arm was lowered through 45°, and a green light was displayed at night  [2.2] . In the 'clear' position, the arm dropped down vertically to be hidden inside a slot in the post, and a white light was shown at night  [2.3] . By the 1860s, semaphore signals were in widespread use, apart from on the Great Western Railway and the Londo...