Railway Control Systems 0713627247

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Railway Signalling

Editorial Committee *0. S. NOCK, A.C.G.l., B.Sc., D.l.C., C.Eng., F.l.C.E., F.I.Mech.E., F.I.R.S.E. Chairman J. H. FEws, C.Eng., F.I.R.S.E., F.I.E.E. R. A. P OPE, M.A., C.Eng., F.l.R.S.E., M.l.E.E. *L. H. F. TUFF, C.Eng., F.I.R.S.E., F.I.E.E. • J. F. H. TYLER, B.Sc., C.Eng., F.I.R.S.E., F.l.E.E., F.C.I.T. *D. C. WEBB, C.Eng., F.I.R.S.E., F.I.E.E. •Past-Presidents of the I.R.S.E. The Committee must express their appreciation of the contributions made by the following: Messrs B. G. Buckler, A. D. Fleet, D. J. Glyde, J. V. Goldsbrough, B. H. Grose, D. A. Hotchkiss, R. T. Hutt, P. C. James, C. Law, C. A. Porter, A. J. R. Rowbotham, G. C. Smith, D. H. Stratton and R. B. Woodhead. The circuit diagrams and signalling plans were prepared by D. A. Wood.

First published 1980 Paperback edition 1985 Reprinted 1988, 1989 A & C Black (Publishers) Limited 35 Bedford Row, London WCI R 4JH

© 1980 Institution of Railway Signal Engineers All rights reserved . No part of this puhlication may be

reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, photocopying, recording or otherwise, without the prior permission in writing of A & C Black (Publishers) Limited

British Library Catllloguing in Publication Data Railway signaUiug: a treatise on the recent practice of British Railways. I. Railroads-Great Britain-Signal I. Institution of Railway Signal Engineers II. Nock, Oswald Stevens

625.1 ' 65' 0941

TF615

ISBN 0- 7136-2724- 7

Typeset by Santype I nternational Limited, Salisbury, Wilts. Printed in Great Britain by Antony Rowe Limited, Chippenham

Railway Signalling A treatise on the recent practice of British Railways Prepared under the direction of a Committee of the Institution of Railway Signal Engineers under the general editorship of

0. S. NOCK Honorary Fellow and Past President of the Institution

A & C Black · London

Contents and Illustrations Foreword Preface

The Philosophy of RaiJway Signalling 1:1 British Railways' multiple-aspect signalling system 2

Layout of Signals and Track Circuits 2:1 2-aspect signalling : (A) Rapid Transit (B) British Ra ilways 2:2 3- and 4-aspect signalling 2:3 2-Yellow headway in 4-aspect area 2:4 British Railways' standard braking ·w· curve 2:5 British R ailways' standard composite brak ing curve 2:6 Optimum headway and line capacity and effect of running at a speed less than that for which the line is signalled 2:7 Theoreti cal and practical oraking technique 2:8 Stopping headway at an intermediate station 2:9 3-aspect stopping headway calcula tions for an inte rmed iate station 2: 10 4-aspect stopping headway calculations for an intermediate station 2: 11 Effect of trai n speed on headway 2: 12 Signalling at an intermediate station with loop platform 2: 13 Layo ut of signals at a converging junction 2: 14 Layout of signals at a double junctio n 2: 15 Layout of signals at a left-hand double running junction 2:16 Double running junctions o n high speed lines 2: 17 Track circuiting at a divergence of two tracks 2: 18 Track circuiting at a crossover between parallel runn ing lin es 2: 19· Track circuiting at a left-hand double junction 2:20 Track circuiting at a left-hand do uble running junction 2:2 1 Su bsidiary signal at entrance to siding or yard 2:22 Subsidiary signal at entrance to occupied platfo rm (simple case) 2:23 Subsidiary signal as draw-ahead for setting back into siding 2:24 Shunting signals and associated track circuiting 2:25 Signalling and track circuiting at a terminal station 2:26 3-aspect ju nction signalling 2:27 4-aspect junctio n signalling

3 The Principles of Interlocking and Cont rolu m ':JL.l ooC( r< >(\I -'w

QC

y 4%AT R

0

Q. Q.

0

VJ.

508 8·2

~0::




508

c

757 * 1

*1 Fig. 3: 14

7- SECOND TIME DELAY ON DETECTION DURING MOVEMENT OF POINTS WHEN 508 C OPERATED .

Example of signa l a nd ro ute control table 75

CONDITIONAL

REQUIRES TRACKS

SETTING

0

0

z V'l .... z

0 Cl..

SET AND LOCKED NORMAL BY Roures

76$

z0

i= (/l

0

Cl.

SOSA . 5058.

7b4

SET AND LOCKED REVERSE BY ROUTES

.... w

1/) 1/)

V'l

w

WI-

w 1- 01. U.l/)

z

6

~

0

Cl. 01-

Vl

w 1- .J

u

01.

~

Q{

:ll

oct

1-

5088-1.

S06A. SOSA .

::l

0 0

RToN

N TOR

REMA!ii!KS

4SI(M)D 5038 .

SOSB .

sosc.

5068.

5088-2 .

CJl

oct

.... z

0

Cl.

~ 01.

0

z UK w 765N OR 766R .

UJ. VH.

764

5088-2 .

481(M)C . 503A.

:z

TN. UK .

.

765

Fig. 3:15 Example of point control table maintained and to prevent the signal returning to Red the detection is bridged out during a 7-second time lag to avoid a disconnection during the operation of the point machine. The signals in rear of 508 are automatic and will clear in sequence after the passage of a train. Hence there is no need for approach locking track circuits VM and VL to be conditional on 520 and 516 being OFF. The approach locking is released by VK clear after VK and VJ have been occupied; in effect this amounts to a ' last-wheel' release as the train clears VK. This combination of occupied and clear track circuits prevents a false release of the approach locking by a 'bobbing' track circuit or an insulated block joint failure (which would cause two track circuits to fail). Other points to note are the absence of separate overlap track

76

circuits at the automatic signals 5 16, 520 and 526 and similarly at the controlled signals 498 and 500. At the last two signals, the speeds are low and the overlaps are so short that separa te track circuits would not be warranted for flank protection alone. In Fig. 3:16 there is an example of short track locking distance. Points 757 are situated only a short distance from signal 496 and in consequence .must be locked by TM with a time release. This is shown in the point route locking table as TM clear or TM occupied with a I 0-second release. A further point to note concerns the signal route locking. All track circuits which effect this route locking are situated between the end of the overlap at signal 498 (that is, at the joint between UH and UG) and the platform starting signals. They are not shown in the diagram (except for UG). The purpose

POINT ROUTE LOCK ING

SIGNAL ROUTE LOCKING

0

z

TRACKS

(/)

z 0

t-

z

z0

AFTER SIGNAL OPERATED

T M OR TM OCCUPIED .

764

VJ .

10

0

5088 - 2.0

(/)

T J . UB. UC . UF. UG.

sosc .

491C.

508 UB. UC . UF. UG. B-1 UE . UF". UG.

493C. 495. '

497. 499.

VB. VE . UF. UG .

sosc.

AFTER SIGNAL OPERATED

u w

0 0!

SOSA . 5086-1 .

VJ . UL.

z

::J

(/)

757

0

1-

w

0..

1/)

TRACKS

w

u

0

766

(/}

0

VE. VC. UF. UG.

APPROACH LOCKING

:z ...J

TRACKS