The electrical detector is an electromechanical device to check the position for correct setting and locking of points through making an electrical contact, which closes a circuit. It has two sets of fixed contacts. In centre, bridging contact assembly on a roller cam shaft, which works in conjunction with the points and lock slides, makes the fixed contact as per the point setting.

Point operating member (i.e., lever position) in the circuit ensures correspondence between lever position and point detection.. Normal shunt and reverse shunt contacts in the circuit ensure the conflicting relay is not energized from false or cross feed to ensure safety.

Shunt & Detection contact position during & after point operation.

Supply to different functions vary according to the type of signaling and type of equipments used .

For example, signal heads may be fed at 110/12 V  AC, 12 V DC, or maybe of LED type.

Normally, the input to signaling installations will be of 650Volts which is stepped down and distributed as per requirements. Standard equipment like 650/110V transformer of different ratings, 110/24V T/Js, 110/12V T/Js

etc are to be installed in the R/Rooms and field locations for signaling purposes. Besides, there may be items like Location lamps, heaters etc which are to be fed from the power source available in the location.

Where the production of designs for a new installation is involved, the total power requirement may be calculated by taking the maximum possible load of each function into consideration. For example,    the maximum load of a four aspect signal is taken as two lamps lit at a time (double yellow).

The capacity of the feeding source (transformer, T/J etc) is arrived at by taking the load of all the equipment proposed to be connected to it.

Power calculation of existing installation undergoing alterations needs to be done in two steps:

Calculation of the existing load

Calculation of the additional load

Arrive at the final figure of load by adding items 1 & 2  and check if the existing Transformer / T/J can meet the additional requirement. If the total final load does not exceed 90% of the capacity, the feeding equipment can be retained, and if not it stands for replacement.

A typical Power Calculation sheet of EY1 R/R is provided for reference.

Load Calculations, Railways Signalling Equipment Power Calculations, Calculation of the existing load, Calculation of the additional load

General – (1) All running tracks shall be inspected as per the schedule defined in Special Instructions.
(2) All Metro Railway employees whose duties require them to go on the tracks shall be properly trained and certified as Authorised Employee for the purpose of sub rule (1).

(3) All Metro Railway employees who go on the tracks shall wear appropriate high visibility clothing, helmet and boots.

Track work and trackside work in nontraffic hours – (1) No maintenance staff shall enter onto the track of any running line without the permission of the Traffic Controller.

(2) Non-traffic hours are defined as the hours between the passage of the last train, including any work train, and a published time before start of traffic again in the morning and the normal time shall be published in the relevant handbooks which may be varied from time to time by the Metro Railway.

(3) The maintenance staff requiring to carry out inspection or repair of equipment which does not affect the integrity of the track nor require the use of ladders or scaffolding and not involving danger to trains or traffic, may enter on the track under the following conditions, namely:-

(a) the Traffic Controller shall give permission, specifying the location and are a for which permission is given and the time by which staff shall have to leave the track;

(b) the Traffic Controller shall log the time, location and the name of the person to whom permission under clause (a) has been given.

(c) on completion of the work, the person to whom permission has been given under clause (a) shall report to the Traffic Controller, identify him self and affirm that he and his equipment are clear of the track and that it is safe for service to resume.

(d) if the work cannot be completed within the allotted time, the person to whom permission has been given under clause (a) shall inform the Traffic Controller before the expiry of the time he has been allotted and agree with the Traffic Controller for an extension of time and the institution of an Engineer’s Possession; and

(e) the Traffic Controller shall not permit the start of normal service until all permissions to work have been properly given up and rescinded.

(4) All other works carried on in non traffic hours shall be protected by an Engineer’s Possession. 

Track work and track side work which extends into traffic hours – (1) All works which are planned to extend beyond non traffic hours into the hours when train services normally operate shall be notified at least a fortnight in advance.

(2) All such works shall take place within an Engineer’s Possession.

(3) Works which are planned to be carried out within non traffic hours without an Engineer’s Possession but which are delayed by unforeseen circumstances shall be protected by an Engineer’s Possession.

(4) The train services on adjacent sections of the line shall be operated with appropriate caution order or other precautions as prescribed in special instructions.

DEFINITIONS

• PERMISSIBLE SPEED – The authorized maximum speed over a section of line.

• TEMPORARY SPEED RESTRICTION – A speed, less than the permissible speed, applied for a pre-planned period not normally exceeding 6 months.

• EMERGENCY SPEED RESTRICTION – A speed restriction not shown in the Weekly operating Notice (WON), or which is more restrictive than shown, or which applies at a time other than that shown in the WON.

• WEEKLY OPERATING NOTICE– The official printed notice advising drivers of alterations to permissible speeds.

AUTHORISATION

• The value of all permissible speed and temporary speed restrictions shall be authorized by the Infrastructure Controller.

• On lines which are used in both directions, it is possible to authorize different speeds for each direction of travel.

CLARITY OF SIGNING

Signing of speeds and restrictions should give clear and unambiguous information to  the driver.

All boards and indicators should generally be placed to the left of the track. In cases where it is not possible to do so they should be placed on the right hand side after due verification that they would not cause any confusion to the driver and/or be misread as applying to another line.

Positioning should be considered in relation to all other signs/indicators so that the information conveyed to the driver is clear.

Permissible speed Indicator

* Speed indicators for standard speeds shall comprise a single indicator displaying  the speed.

Differential speeds

Differential (Speed Restriction) : A speed restriction having two varying restrictions, each of which is applicable to different types of train.

Speed indicators for standard differential speeds shall comprise a single indicator displaying  the lower speed above the higher.

Permissible speed Indicator- Converging junction.

* Where permissible speed beyond a junction is the same as that on the higher speed route through the junction and is higher than the speed on the converging route, a speed indicator is not required for trains approaching from the converging route.

* It is permissible to provide a miniature speed indicator as a repeat sign immediately after a converging junction where the permissible speed beyond the junction is higher than that on the converging route.

Permissible speed Indicator- Diverging junction : 

* A speed indicator with an arrow indicating the direction of the diverging route shall be provided immediately before any diverging junction over which there is a reduction in speed.

*  Where a lower permissible speed applies equally to both the routes a single permissible speed indicator shall be provided without directional arrows.

* Where differential speeds commence for each route at a diverging junction, two indicators shall be positioned side by side. Arrows shall be provided to indicate any divergence.

Temporary Speed Restrictions – Procedures

* The infrastructure controller shall devise and apply procedures for the administration, implementation, alteration and withdrawal of temporary speed restrictions. The procedures shall be documented and responsibilities shall be clearly defined.

* Any temporary alterations required are fully documented and approved by the infrastructure controller, and the implementation of the alterations is co-ordinated with the introduction and withdrawal of the temporary speed restriction.

* Equipment is provided and removed at the correct time, is correctly positioned.

*  Implementation of temporary speed restriction shall only commence after notification to the drivers has been given through WON. Where this is not possible ,it shall be treated as a emergency speed restriction.

*  Temporary speed restrictions are generally for less than six months period.

Emergency Speed Restriction

The infrastructure controller shall have a documented procedure for advising emergency speed restrictions to drivers.

PERMANENT SPEED RESTRICTIONS

TPWS will be provided to protect Permanent Speed Restrictions on passenger lines where the approach speed is 60mph or more, and the speed reduction is one third or more.

PSR INITIAL SELECTION

Initial selection for fitment of TPWS on a PSR is done as per flowchart in Appendix C of RT/E/S/10137 Issue 3.

Additionally TSRs that are planned to be in place for greater than six months but not exceeding 12months  shall be considered for fitment subject to risk assessment in accordance with flowcharts in Appendices D & E of RT/E/S/10137 Issue 3.

PSRS REQUIRING FITMENT

PSRS REQUIRING FITMENT:

A  Plain Line on curve

D  Approach to converging junction

Ei  Approach to vehicular level crossing

G  Approach to Terminal Platforms

I  Provided for Reduced Signal Spacing / Overlap

Jii  Provided for Asset protection safety

Ni  Diverging Junction – Signal not Approach Released

Niii  Diverging Junction with splitting distant (No Approach Control Signalling)

PSRS NOT REQUIRING FITMENT – EXCLUSION CODES

B  Diverging Junction – Approach Released from Red

C  Diverging Junction – Approach Released from Y/YY

Eii  Approach to footpath or bridleway crossing

EXI  No protection provided to passenger trains due to freight   train timer issue

F  No longer used (was PSRs on RETB Lines)

H  Approach to Emergency crossovers

Ji  Provided for Asset Protection (Commercial)

K  Provided for Gauging or Aerodynamic Purposes

Mi  Attainable Speed less than 60MPH

Mii  Attainable speed less than agreed Excessive Speed

Nii  Diverging Junction indicated by Flashing Aspects

Q  Trackworker protection

PERMANENT SPEED RESTRICTIONS

Figure below shows the general positioning layout of the OSS on the approach to a speed restriction.

Following the initial selection, final selection shall be carried out in accordance with Appendix E of RT/E/S/10137 Issue 3, using Excel spread sheet TI-14_6.xls

Due to the complexity of determining loop positions and the iterative process of determining fitment criteria based on issues involving train performance, these calculations shall only be made by using the design tool developed and validated specifically for this purpose by AEA Technology Rail – “TPWS at Speed Restrictions: Loop Positioning Spreadsheet – June 2003 Issue 6.0” (TI-014_6.xls). The input page for general application is shown in the next slide.

Metro Rail Emergency track side work traffic hours – (1) No routine maintenance shall be undertaken during the hours in which train services normally run except as provided for in sub-rule (2).

(2) If emergency repair work is required to be carried out to prevent accidents or to maintain or restore train services, such emergency work shall be done under the Engineer’s Possession which shall be granted by the Traffic Controller without delay taking the exigencies of trains services into account and making adjustments in train schedules.

Engineer’s Possession – (1) Engineer’s Possession on running lines is granted by the traffic controller who has final responsibility on whether or not the Engineers may take possession.

(2) All works on tracks in depot shall be undertaken within an Engineer’s Possession which shall be granted by the Depot Controller but in other matters the rovisions hereinafter provided shall apply.

(3) An area under the Engineer’s Possession is the sole responsibility of engineering official in charge and all issues of safe working within that area including the movement of trains is his responsibility.

(4) The person in charge of Engineer’s Possession shall be trained in the duties and responsibility of the role and certified so by the Authorised Official or institution of metro railway.

(5) If more than one maintenance unit is working within the same possession, one person shall be nominated by the Traffic Controller as the person responsible for the coordination for the work of all the units, as per special instructions.

(6) When possession is granted under sub rules (1) and (2), the engineering official in charges shall protect the area of the possession from access by trains in one of the following ways, namely:-
(a) securing a vehicle at the limit of the possessing;

(b) securing points for a route which diverts trains away from the area of possession;
(c) using visual warning means for protection; and
(d) any other means as per special instructions.

(7) For running line signalled for operation in either direction, protection shall be implemented at all points of potential access and different methods may be used at each location in accordance with the sub-rule(6) .

(8) If a work train or self propelled maintenance vehicle is to be used within the possession area, it shall arrive at site before possession is taken and lamps displaying red aspects restricting movement towards the possession area shall be placed at the limits of the possession or on the secured vehicles where these are used to protect the possession
area.

(9) Where work on one track is likely to affect the passage of trains on an adjacent track, possession shall be taken of all tracks likely to be affected.

(10) If trains are required to pass on an adjacent track, the person in charges of the possession shall be responsible for ensuring that the track is safe to use before giving permission by hand signal.

(11) Unless essential for the movement of trains, traction power shall be switched off from the area of the possession by the Traction Power Controller and shall only be re-energised on receipt of clearance.

(12) All switching ON or switching OFF operations of traction power required for maintenance work or Engineer’s Possession or for any other purpose shall be approved by Traction Power Controller.

(13) The person in charge shall be responsible for confirming to the Traffic Controller on completion of the work that the track is safe for traction power to be switched on, all protection measures have been removed and the track is safe for trains to run.

(14) All Engineer’s Possession shall normally be authorised only under staff protection keys, where provided.

Types of Signals :- Signal is a medium to convey a particular pre-determined meaning in non-verbal form.

Multiple Aspect Color Light Signal (MACLS): Multiple means more than 2 indications .They may have 3 or 4 different aspects or indications to be given to the driver. These signals have longer range of visibility and Improved reliability.

Classification of CLS:

Manual Stop Signal :

Each aspect of the signal is represented by a circle. A horizontal line inside the circle indicates Red aspect, an inclined line the yellow aspect and vertical line the Green aspect. The normal aspect of the signal is shown by double line.

Permissive Signal (Distant Signal):

Shall be located at an adequate distance in rear of the stop signal, the aspect of which it pre- warns. The normal aspect of permissive signal is „Single Yellow„ where 2 distant signals are provided to pre- warn the stop signal, the outer most signal, to be located at an adequate distance from the first stop signal, shall be called the distant signal and the other called the inner distant signal, with the distant capable of displaying „ attention „ or „ proceed‟ aspect only .

To distinguish between stop signal and permissive signal „ P „marker board (letter in black on white board) is fixed to the permissive signal.

Automatic Stop Signal :

The normal aspect of an automatic signal is green and is indicated by the double vertical line, unlike the manual signal where the normal aspect is red and indicated by double horizontal lines. An automatic signal has an „A‟ marker plate fixed to the signal post to distinguish it as an automatic signal. Letter „A‟ in black on white circular disc.

Semi-automatic Stop Signal :

An illuminated „A‟ marker distinguishes a semi – automatic signal from a fully automatic signal. Letter „A‟ against black back ground is illuminated when working as an automatic stop signal and letter „A‟ extinguished when working as a manual stop signal.