Track irregularities and vehicle responseTomas Karis, Mats Berg & Sebastian StichelKTH Railway Group

Agenda• Introduction• Theory and method• Preliminary results• Conclusions and next steps

2KTH RAILWAY GROUP

Introduction

3KTH RAILWAY GROUP

Track irregularities and vehicle response• How closely correlated are

track irregularities and vehicle response?

• Important for • vehicle dynamics certification

(e.g. EN 14363)• track maintenance

(e.g. EN 13848)• With standard evaluation methods

the irregularity-response correlation varies a lot

• Alternative evaluation methods?

4KTH RAILWAY GROUP

Longitudinal level (vertical)

Cant irregularity

Alignment (lateral)

Track gauge

Track centre line

Longitudinal direction

Wheel-rail forces

Track irregularities and vehicle response

Carbody accelerations

Bogie-carbodymovements

Axle box accelerations

Bogie frame accelerations

5KTH RAILWAY GROUP

On-track measurementsGreen TrainSwedish research programme using a modified Regina EMU as a test bench.

DynoTrainEU project aiming at resolving openpoints in EN 14363

6KTH RAILWAY GROUP

Theory and evaluation methods

7KTH RAILWAY GROUP

Track evaluation methodsParameter Common data Gröna Tåget Dynotrain

Longitudinal level zt

Tangent track, both rails

Wavelength D1: 3 – 25 m,Dx: range corresponding to Q-forces 0.4 – 20 Hz

STRIX 1-140 m Raillab 1-70 m

Assessment 99.85 % or standard deviation

Sections Length 100 – 250 m 7 (165 km/h) 33 (165 km/h)

Correlation coefficient 𝑅"# =

𝐶𝑜𝑣(𝑥, 𝑦)𝑉𝑎𝑟 𝑥 𝑉𝑎𝑟(𝑦)

8KTH RAILWAY GROUP

Vehicle dataVehicle Dynotrain vehicle 1 Dynotrain vehicle 2 Gröna Tåget

Type Locomotive Passenger coach Two-car EMU

Model BR120 501-2 Bim 547.5 Regina X52

Permissible speed 200 km/h 200 km/h 250 km/h

Bogie Stiff Fairly stiff Fairly soft

Axles Four Four Eight

Driven axles Four - Eight

Mass 84 t 35 – 40 t 2 x 70 t

9KTH RAILWAY GROUP

Vehicle evaluation methodsParameter Common data Gröna Tåget Dynotrain

Q-force Tangent track, BP 0.4 – 20 Hz,99.85 % or standard deviation

Vertical axle box acceleration

Tangent track, LP 20 Hz

Speed [km/h] 165 250 – 300 110, 200

Speed variation ±5 %

Vehicle type EMU Loco+coach

Correlation coefficient 𝑅"# =

𝐶𝑜𝑣(𝑥, 𝑦)𝑉𝑎𝑟 𝑥 𝑉𝑎𝑟(𝑦)

10KTH RAILWAY GROUP

z(t)m

k cv

mw zw(t)

zt(s)

s

A Fk,d Fc

Qd

Theory for irregularity–response pairs𝑄1#2 = 𝑚�� + 𝑚7��7 = 𝑚�� + 𝑚7𝑧𝑡′′𝑣:

11KTH RAILWAY GROUP

𝑄𝑑𝑦𝑛 vs 𝑧𝑡 → 𝑄𝑑𝑦𝑛vs 𝑚𝑤��𝑤 &��𝑤 vs 𝑧𝑡

→ A7B: vs 𝑧𝑡′′ &𝑧𝑡′′ vs 𝑧𝑡��𝑤 vs 𝑧𝑡

Preliminary results

12KTH RAILWAY GROUP

Preliminary results, Bim 547.5

13KTH RAILWAY GROUP

Preliminary results, Bim 547.5: 𝑄𝑑𝑦𝑛vs𝑧𝑡

14KTH RAILWAY GROUP

Always D1, unlessotherwise stated

Preliminary results: 𝑄𝑑𝑦𝑛vs𝑧𝑡

15KTH RAILWAY GROUP

Preliminary results, Regina 250: 𝑄𝑑𝑦𝑛vs𝑧𝑡

16KTH RAILWAY GROUP

Preliminary results: 𝑄𝑑𝑦𝑛vs𝑚𝑤��𝑤

17KTH RAILWAY GROUP

Preliminary results, Bim 547.5: 𝑄𝑑𝑦𝑛vs𝑚𝑤��𝑤

18KTH RAILWAY GROUP

Preliminary results: ��𝑤vs𝑧𝑡

19KTH RAILWAY GROUP

Preliminary results: A7B:vs𝑧𝑡′′

20KTH RAILWAY GROUP

Preliminary results: 𝑧𝑡′′vs𝑧𝑡

21KTH RAILWAY GROUP

Discussion

22KTH RAILWAY GROUP

𝑄𝑑𝑦𝑛 vs 𝑧𝑡

𝑄𝑑𝑦𝑛vs 𝑚𝑤��𝑤

A7B: vs 𝑧𝑡′′

𝑧𝑡′′ vs 𝑧𝑡

Conclusions and next steps

23KTH RAILWAY GROUP

Conclusions• 𝑄𝑑𝑦𝑛vs𝑧𝑡 gives often poor results• 𝑄𝑑𝑦𝑛vs𝑚𝑤��𝑤 resp. 𝑧𝑡′′vs𝑧𝑡 strongly related

• Weak link is A7B: vs𝑧𝑡EE

• More samples needed• Wavelength range Dx not generally better than D1

24KTH RAILWAY GROUP

Next steps• Increase number of samples• Identify disturbances (e.g. switches)• Effect of other irregularities than zt• Effect of track flexibility• Simulations with different models

25KTH RAILWAY GROUP

Thank you for your attention!

26KTH RAILWAY GROUP