Stds Of Interlocking

Standards of Interlocking As per old manual (of 1955)

Standards of Interlocking • Old SEM (para 170 for 2 aspect & para 174 for multiple aspect) lays down the following Standards of Signalling and interlocking: – Standard I – Standard II – Standard III

Permits speeds upto 50 kmph Permits speeds upto 75 kmph Permits unrestricted speed

for run through trains

Standard I • SEM para 171 lays down the requirements for Std I for 2 aspect Signalling. – (a) Isolation: Not compulsory. – (b) Signals : Outer and Bracketted Home Starter is optional Warner only on MG, if trains run through. All signals to be operated from a Lever frame under SM’s control. – (c) Points : As per para 142 – (d) Interlocking: (i) Between facing points and signals by key locks shall be so arranged that a signal cannot be taken off unless the facing points are correctly set and locked.

Standard I (contd.) (d) Interlocking (cotd.) : (ii) If warner is provided, interlocking between warner and points must extend to trailing points. (iii) If points keys are electrically transmitted, insulation standard shall be same as for Block wires. (iv) Interlocking between points and signals must ensure that no signal can be taken off for a line fitted with trap points unless the trap point has been closed.

Standard II • SEM para 172 lays down the requirements of interlocking for Std II for 2 aspect signalling. – (a) Isolation : Main line must be isolated. – (b) Signals : Outer, Warner and bracketted Home Starters are optional Where Starter is not provided, warner shall prove receipt of Line Clear on the BI – (c) Points : As per para 143 – (d) Interlocking : (i) Interlocking between points and signals may be direct or indirect. All signals must be operated from a lever frame controlled by SM.

Standard II (d) Interlocking (contd.) : (ii) Interlocking between points and signals same as for std I and must ensure correct setting of all trailing points for movement over them. (iii) If points and signals are operated from either end of station, interlocking between them must be direct. (iv) SM should have control over Home and LSS.

Standard III • SEM para 173 lays down the requirements of interlocking for Std III for 2 aspect signalling. – (a) Isolation : Main line must be isolated. – (b) Signals : Outer, Warner, Bracketted Home and Starter. Adv str as necessary. – (c) Points : As per para 144 – (d) Interlocking : Between points and signals must be direct and comply with requirements in section A - J. • Note 1: A passenger warning board at 1 km and Goods warning board at 1.4 km in rear of Outer should be provided if warner is not separated. • Note 2: Unrestricted speed over indirectly interlocked siding points may be permitted if point equipment is as per para 144

Standards of Interlocking for multiple aspect signalling • Para 174 (ii) lays down the requirements of isolation, • Para 174 (iii) lays down the requirements of signals, and • Para 174 (iv) lays down the requirements of points equipment and interlocking

Standards of Interlocking for multiple aspect signalling • • • •

Isolation requirements : No difference Equipment of Points : No difference Interlocking requirements : No difference Signals : – Std I : Distant and Home – Std II : Distant, Home and Starter – Std III : Distant, Home and Starter

Equipment of Points • Para 141: For speeds upto 15 kmph over facing points • Para 142: For speeds upto 50 kmph over facing points • Para 143: For speeds upto 75 kmph over facing points • Para 144: For speeds in excess of 75 kmph over facing points

Equipment of Points • Para 141: – (i) A bolt and cotter individually fitted to each switch rail and padlock or a clamp and a padlock for locking the switch rail to the stock rail. – (ii) A gauge tie plate where steel sleepers are not provided.

Equipment of Points • Para 142: – (i) A key lock of approved type. – (ii) A means for locking each switch independently. – (iii) A means for preventing the points from being unlocked during the passage of the train, unless the arrangement is such that a key is used to release the signals and cannot be brought back to the points until such signals have been put to the ‘on’ position. – (iv) A means for detecting each switch independently by the relative signals. – (v) A gauge tie plate where steel sleepers are not provided.

Equipment of Points • Para 143 : – (i) A plunger type facing point lock. If the plunger is hand operated or is of the economical lock type, its full travel should be detected by the relative signals. – (ii) to (v) : Same as for Para 142 (ii) - (v) – –

– –

(ii) A means for locking each switch independently. (iii) A means for preventing the points from being unlocked during the passage of the train, unless the arrangement is such that a key is used to release the signals and cannot be brought back to the points until such signals have been put to the ‘on’ position. (iv) A means for detecting each switch independently by the relative signals. (v) A gauge tie plate where steel sleepers are not provided.

Equipment of Points • Para 144 : – (i) A plunger type facing point lock. – (ii) A means for detecting the full travel of the lock plunger by relative signals when the lock and switches are operated by the same lever.(It is desirable that plunger detection is also provided for independently operated FPLs. – (iii) A means for preventing the points from being unlocked during the passage of train. – (iv) to (vi) : Same as Para 142 (ii), (iv) & (v)

Comparison 1. Isolation Item Main line isolation

Isolation of passenger lines from goods lines & sidings

NI

Std I

Std II

Not required

R

E

Q

Std III

Required

U

I

R

E

D

Comparison 2. Signals Item Two aspect: A class Two aspect: B class Two aspect: C class

NI

Std I

Std II

Not usually adopted Outer & Common home

Outer & Bracketted home Warner in MG, if reqd.

Outer & Bracketted home. Warner should interlock with B.I., if strs not provided

Not usually adopted

Std III Warner, Home, Starters Outer, Bracketted home, Warner & starters Warner, Home

Comparison 2. Signals Item Multi aspect: B class

Multi aspect: C class

NI

Std I

Std II

Std III

Distant, home

Distant, home

Distant, home, Starter

Distant, home, Starter

Not usually adopted

Distant & home

Comparison 3. Points Item Operation

Locking

Switch Detection Lock Detection Route Holding

NI

Std I

Locally

operated

Bolt & cotter Key lock of approved type Not required

Not d NA

Std II

Std III From a lever frame where points & signals are grouped

Plunger type FPL, Plunger type which may be FPL operated hand operated from LF

A means for detecting each switch independently should be provided

r e q u ir e

Reqd if Hand operated Key used to release signals cannot be brought back till signal is replaced to ON

Desirable Lockbar or TC

Comparison 4. Interlocking Item Interlocking

NI Not required

Std I Indirect by key locks. Warner should interlock trailing points. Direct locking bet signals

Std II

Std III

Indirect by key locks extends to trailing points. Direct locking bet signals

Direct interlocking bet signals and points.

Important points: • The major difference between Std I and Std II is that of isolation. • Std I and Std II are generally used on low density routes (mostly single line sections). • In Std I, the points are individually operated by spring loaded levers whereas in Std II, they are grouped and operated from a small ground frame. • In Std I, Home need not be interlocked with trailing points whereas Std II requires this interlocking. • Std III does not permit indirect locking between points and signals.