degradation processes and wear of railway switches & crossings the

Willem-Jan Zwanenburg – Rail Tech Europe, Utrecht 27-29 March 2007Seminar 6: Switch Design & Maintenance

1ÉCOLE POLYTECHNIQUEFÉDÉRALE DE LAUSANNE

EPFL – LITEPÉcole Polytechnique Fédérale de Lausanne, Switzerland

Laboratory for Intermodality, Transport & Planning

Degradation Processes and Wear of Railway

Switches & CrossingsThe Swiss Experience

Willem-Jan Zwanenburg



SBB network



Problems with Switches & Crossings

- straight AND curve (with small radius)

- standard components AND specialcomponents

- moving parts

- high dynamic and concentrated loads

- component failure can lead to immediate accidents



Deterioration and degredation (wear)

Parameters causing deterioration/degradation:

1. Train loads (speed, axle loads, amount of trains)

2. Train type3. Amount of trains in diverting direction4. Amount of actuations5. Real speed (not design speed)6. Sub-soil state7. Accuracy of placement



Correlations

State of track geometry State of track material

Train loads on the

railway track

Maintenance and

renewal works

Restoration

Degradation



Model 1

Switches & Crossings

(component) description

Train loads

Switch utilisation

Measurement data+ +

+ SBB expert knowledge specific for Switzerland (30% of curved switches)

=attribution of degradation and deterioration



Model 2

= planning of - Optimisation of inspection and surveillance- Optimisation of maintenance and renewal

Works on S&C

+



Degradation profile 1

To determine degradation and wear rate

Quality

1988 2005

Trend ?

Qmin

2008

Linear Progressive

Regressive Instantaneous

Time



Degradation profile 2Quality

Qmin

Time?MGT?

Train speedV2>V1

V1V2



First steps, model 1

→ renewal age of complete S&C (1988-2005)To test following hypothesis:a) S&C incorporated in more important track types (more

and/or faster trains and/or heavier axle loads) will show higher deterioration rates than S&C in tracks with a lower density of trains or lighter trains;

b) Curved S&C have a shorter lifetime than S&C on plain track;

c) S&C with a smaller angle show less wear (i.e. a 1:15 switch will show less wear than a 1:9 switch).

SBB database “DfA”



Importance of track load on wear


4.018.2double diamond

crossingHG1

4.323.8simple turnoutHG3



Standard deviation (years)

Average replacement age (years)

S&C typeTrack category

Conclusion: Track load has an effect on the wear



Curved switches show more wear


3.013.8simple curved turnoutHG1

3.213.8simple straight turnoutHG1

Standard deviation (years)

Average replacement age (years)

S&C typeTrack category

Conclusion: The effect of curvature on switch degradation cannot be proven with this data set.



S&C with smaller angle show less wear


5.317.51:24

5.816.11:21.5

4.111.21:19

3.115.41:16

3.314.31:14

3.315.51:12

1.717.11:9

5.616.11:8

8.121.21:7

Standard deviation (years)Average replacement age (years)S&C angle

Nothing can be concluded



Average replacement age

+ safety reason (e.g. more wear -> derailment)

+ technical reason (e.g. not servicable anymore, no spare parts)

+ economical reasons (maintaining it perhaps more expensive than replacing it)

+ reliability issues

+ etc.

⇒ Discussion necessary



The next stepsMore in-depth analyses for:Train parameters- Number of trains- Axle loads- Train speed- Train type- Direction of push-pull

trains

Track parameters- Subsoil quality- Installation quality- Other S&C properties

Not only for complete S&C but also for different components:point rails, check rails, sleepers, ballast, crossings



PhD Study

Model testing possibility:

1. Use an „old“ database (e.g. of 1997) with sufficient history (track loads, previous renewals);

2. Use the models to calculate the potential need for switch maintenance and (partial or complete) renewal for the period to 2007 (10 years) based on a track load scenario (these track loads might be the real

loads for the period 1997-2007);

3. Compare the calculated results with the actually carried out maintenance and renewal.



Thank you for your attention

Willem-Jan Zwanenburg

EPFL - École Polytechnique Fédérale de LausanneENAC - Environnement Naturel, Architectural et Construit

LITEP - Laboratoire d'Intermodalité des Transports et de PlanificationStation 18, Bâtiment GC

CH - 1015 Lausanne, SwitzerlandPhone +41 21 693 63 01 Fax +41 21 693 50 60

[email protected]

degradation processes and wear of railway switches & crossings the

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