Railway Signal Engineering

  Repeating Signal - (GR 3.16) A Signal placed in rear of a fixed Signal for the purpose of repeating the aspect of fixed Signal in advance to the Loco Pilot of an approaching train  is called a Repeating signal      A Repeating shall be provided with an R marker and shall be of-  a) banner type b) a square ended semaphore arm,or c) A colour light Signal  Repeating Signal is on different post from Main Signal. Repeating Signal has two aspects, Yellow and Green.It shows Yellow when main signal is ON and  Green when main Signal is OFF. Exact location of Repeating Signal is decided by Signal Sighting Committee. Co acting Signal  - No of Aspect of Main Signal = No of Aspect of Co acting. No marker on Co acting Signal  Co acting Signal is on same post on Main Signal

  SEM 7.1.19  & GR 3.14 Shunt signal are two types - Dependent  and Independent  Shunting can be done only in jurdiction of Staion Master in Station Section . Speed during shunting should be maximum 15 kmph. For shunt Signal,  tracks,points and LC gates in the route are taken but points in the isolation and overlap are not taken.Birthing track is also not proved.Lowering of Shunt Signal will block conflicting movements of Main and Subsidiary Signal. Shunt Signal will always come with arrow. White arrow with red background. Route of the Shunt Signal is from foot of the Signal to Last point zone before birthing. Implantation   (Rail level -1050 mm) - 2135 mm Above 1050 mm - 2360 mm Pilot on independent Shunt will always lit ( both in ON and Off ) If main signal is ON,  then only Subsidiary Signal below it, can be lowered. No Shunt on Home Signal.Shunt on LSS can be placed with permission of CRS. Shunt movements as far as possible ,be controlled by Shunt Signal. Outer, Home and LSS sh

 Codal life of IPS is 20 years. LMLA battery - 05 years VRLA Battery - 04 years Track relay- 12 years  Quad cable - 25 years

 1)The line on which speed is higher than 50 kmph should be isolated from all other running lines. 2) Passenger lines should be isolated from all other goods line and siding, irrespective of  speed. In any other case Isolation may be desirable but not compulsory. 3) If speed is less than 50 kmph, Passenger line is not required to be isolated from passenger line 4) Catch and Slip Sidings and sidings provided for isolation purpose only. Means of Isolation   1) Sand humps, trap points or other approved means of Isolation shall be provided on all goods lines and sidings at the junctions with passenger lines, the normal setting being such as to prevent the passenger lines from being fouled. 2) At Interlocked layouts, means of Isolation shall be Interlocked with the relevant signals. 3)  No trap point in Main line /Through line.Trap point can be placed in main line with permission of CRS ( under approved special instructions) 4) Sand hump is must after every four station.  If Sufficient dist

  Factors affecting breaking distance:-(priority wise) 1. Train speed 2. Train Load 3. Gradient  4. Brake power 5. Types of brakes 6. Condition of Rail 7. Rail/wheel adhesan   Service Breaking Distance (SBD) The drivers are normally supposed to apply brakes gradually, so that breaking may not cause discomfort to passengers. The breaking distance obtained with gradual application of brakes is called SBD or Normal Breaking Distance (NBD). Emergency Breaking Distance (EBD) When brakes are applied suddenly, the breaking distance required would be less but the rate of declaration may cause discomfort to passengers and in case of freight trains,may damage the consignments.The breaking distance with sudden appliance of brake is called EBD. SBD is 1.2 times EBD The inter signal distance is always based on Emergency Breaking Distance (EBD) Reaction time  When driver approaches and observes a signal, he can not be expected to instantaneously react to the aspect of signal, but after some time. Th

  Speed in Station Section STD 1-  up to 50 kmph  STD  II - up to  110 kmph  STD III - up to  140 kmph  STD IV - up to 160 kmph In STD IV, MACLS Signalling or Movement Authority anyone can be used .For others only MACLS. In STD IV, MTRC ( Mobile Train Radio Communication) and TPWS  both are mandatory  and desired for STD II and STD III. CTC ( Centralized Traffic Control) is  not required for any one .D esirable for STD II,STD III and STD IV.  For STD III and STD IV, Double Distant is Mandatory. On STD II,it is required in section where EBD is more than 1 Km.  Token working is permitted only in STD I. There is no connection of S&T department with speed in block section. Aspects of  Signal - 2 Aspect - Red, Green 3 Aspect- Red, yellow,  Green  4 Aspect- Red,Yellow,  Green,  Double Yellow Aspect Sequence Chart is mentioned in SIP Distant Signal  - If distant signal is no light, driver will stop and then move cautiously. Normal Aspect of Double distant- YY Normal Aspect of Inner Dista

  Shunt Key in UFSBI Shunt key can be extracted only when Block panel is in TGT or LINE CLOSED however shunting in TGT is not permitted. For shunting in block section, shunting key to be removed in Line closed position and give to loco pilot as authority to enter in block section. Before entering train into block section  , SM will exchange private no with next block station . Electromagnetic Impulse Counter -It is a six digit, 10 impulses per second minimum, 24 V DC non resetable type counter. Buzzers -  Cedicom or Piezo make buzzers ( continuous and intermittent) working at 24 volts (+20%-10%) DC for audio alarm is provided to register the BELL CODE sent by other end SM & to register the occupation and clearance of each Block Section. Block Telephone  - This is provided for speech communication with SM at other end of Block Section. Separate block telephone is provided for Separate block section. Block panel has provision for hanging block telephone as Drg no RDSO/S 32019.

  Single line -  Distance between outer most point and Advanced Starter is minimum 120 m and Distance between Advanced Starter and Home Signal is minimum 180 m.In this way Home Signal is 300m behind first facing point Double line -   D istance between Starter and Advanced Starter is minimum 120 m. No fixed distance between Advanced Starter and opposite Home Signal .Home Signal must be placed 180 m behind outer most point. In Double line if first point is trailing then BSLB board is required. If first point is facing then no board is required. Home Signal -  Distance between Home signal and first facing point must be more than  180 m in both Single and Double line .When there is continuous steeper down gradient more than 1 in 260 towards station  between Distant and Home Signal in Single Distant terroritary and between inner Distant and Home in Double distant terroritary  Starter Signal  -Location of Starter is just beyond birthing track.  All Starter signals will be released by Advance

  Block overlap   SEM .7.1.8-.  180 meter - Adequate distance ahead home signal only ( used for line clear)                      Signal overlap SEM 7.1.9. -120 meter- Adequate Distance ahead starter signals only if we are lowering Home Signal to receive a train. IB signal overlap -400 meter No Block overlap in  Automatic Block system.Only signal overlap  Automatic signalling possible in singal line but it is rare. Adequate distance - distance to ensure safety  Block overlap and signal overlap are two types of Adequate distance  Fouling mark  - Fouling means the marks at which the infringement of two fixed standard Dimensions Fouling Block  occurs,where two lines crosses or join each other.  It shall be placed at a location,where centre to centre distance :- Minimum 4265 mm ( for existing line) Minimum 5300 mm ( for New construction) Glued joint should be placed more than 3m distance from Fouling mark to avoid side collision because in guard compartment the distance between wheel and

  Validity of CST sanction   is six months .Required when we are doing any changes in existing interlocking.e.g commissioning of BPAC Validity of CRS and PCE sanction are same (01 year). PCE sanction is required only for closing the LC gate.Earlier it was with CRS, now delegated to PCE. ESP,SIP,SWRD,PD and SWR required to be attached with PCE sanction.  CRS sanction is must when do any change in interlocking,e.g.any new line is opened. Validity of CRS sanction is 01 year. CRS permission is required in following cases. a) Additions/extensions or alterations to the existing block, Signalling and interlocking installations b) Change in Block, Signalling and Interlocking installations. c) New stations temporary or permanent. d) Interlocking of level crossings, catch siding and slip sidings etc. CST Sanction   CST Sanction required in following works 1) Provision of Telephone at already Manned level crossings. 2) Provision of electrical & mechanical lifting barrier including emergency

Approved special instructions - Special instructions Approved or prescribed by CRS. There are total 9 CRS in railway  1. Mumbai - CR and WCR 2. Mumbai - WR and NWR 3. Kolkata - ER and ECR 4. Kolkata  - NFR and Metro 5. Kolkata- SER, ECOR,SECR 6. New Delhi - NR 7. Lucknow- NER and NCR 8. Banglore- SR and SWR 9. Secunderabad- SCR CCRS is head of all CRS and his HQ is Lucknow.CCRS acts as principal technical advisor to central government. Special instructions - Instructions issued by the Authorized officer in respect to particular cases or special circumstances. Generally PCOM is Authorized officer  nominated by GM Block back - used for Double line and single line Block forward - used for Double line . Safety Integrity Test To be done once in 05 years ( As per new SEM).