ISO INTERNATIONAL STANDARD 20138-2 First edition 2019-11 Railway applications Calculation of braking performance (stopping, slowing and stationary braking) Part 2: General algorithms utilizing step by step calculation Applications ferroviaires-Calcul desperformancesdefreinage (freinage d'arret, de ralentissement et d'immobilisation) Partie 2: Algorithmesgeneraux utilisant le calcul pas d pas Reference number IS0 20138-2:2019(E) ISO @ ISO 2019 IS020138-2:2019(E) COPYRIGHTPROTECTEDDOCUMENT IS02019 All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either IsO at the address below or IsO's member body in the country of the requester: ISO copyright office CP 40i : Ch. de Blandonnet 8 CH-1214 Vernier, Geneva Phone: +4122.749 0111 Fax: +41 22 749 09 47 Email:[email protected] Website: www.iso.org Published in Switzerland ii IS02019-Allrights reserved IS020138-2:2019(E) Contents Page Foreword iv Introduction. V 1 Scope .1 2 Normativereferences .1 3 Terms and definitions .1 4 Symbols. .2 5 General explanation of step-by-step calculation .3 5.1 Method 3 5.2 Retarding force models 3 5.3 Algorithm 4 5.3.1 General description 4 5.3.2 Time integration. 4 5.3.3 Determination oftimestep/relativedistancedeviation .6 5.3.4 Equivalent system response time te 67 5.4 Supplementary dynamic calculations 5.4.1 Energy dissipated by each brake equipmenttype. 7 5.4.2 Value ofthe instantaneous adhesionrequired between wheel andrail for the braked wheelset (tax) 7 5.4.3 Maximumbrakingpower of eachbrakeequipmenttype .8 6 Considerationsforstopping/slowingdistancesand decelerationcalculations .8 6.1 Accuracyofinputvalues 8 6.2 Distance calculations.. 8 6.3 Generalcharacteristics 8 6.4 Brake equipment type characteristics. 9 6.4.1 General. 9 6.4.2 Input data 9 6.5 Initial and operating characteristics 9 6.5.1 Nominal conditions 9 6.5.2 Wheeldiameter. 9 6.5.3 Initial speed. 9 6.5.4 Gradient 9 6.5.5 Level of the brake demand 9 6.5.6 Degraded mode 9 6.5.7 Degraded condition 10 6.5.8 Available coefficient of wheel and rail adhesion 10 6.6 Other deceleration calculations. .10 6.6.1 General. 10 6.6.2 Decelerations resulting from the force generatedby each brake equipmenttype (ain) .10 6.6.3 Equivalent (mean)'deceleration (a) based on distance .10 7 Immobilization brakecalculation .11 AnnexA (normative)Workflowofkineticcalculations. .12 .13 AnnexB(informative)Calculationofretardingforces(non-stationary) AnnexC (informative)Examplesforbrakecalculation .18 Bibliography .33 @ IS0 2019 - All rights reserved iii