Ballast Migration – Progress 7 March 2013

Presentation by Louis Le Pen

Researchers: Louis Le Pen and Geoff Watson

• Summary of 10th January meeting• First site monitored• Initial results• Summary

Ballast migration at Weedon November 2006

Presentation overview

Meeting 10th January

Present: Gareth Evans (Senior Technology Engineer (Rail)) – project champion, Paul Parcell (WCML), Kevin Thurlow (WCML), Louis Le Pen (UoS), Geoff Watson (UoS)

Key points:•Where this is known to occur Paul applies a tamp twice policy “has helped”•Stoneblowing is also used at locations of rapid deterioration (e.g. Hodge Lane)•On straight sections of track voiding can occur without migration•Paul’s view is that the subgrade is the cause•Could use GPR data to evaluate further (8 week surveys)•During the speed upgrade “this was a major problem”

To London

Site one: Hodge lane access near tamworth WCML

• 4 tracks, inner tracks are fast outer tracks are freight

Site one: Hodge lane access near tamworth WCML

• LEC2 108m to 109m, fast trains to London (second track in photo)• Stoneblown Dec 2012 because “deteriorating fast”• For January 2013 monitoring no visual evidence of migration

Site one: geophone arrangement

Site one: Weld

1346789

High sleeper end

Site one: Geophone Arrangement

25

Vertical

Vertical

Horizontal

1110

Weld

Migration feature

How geophone data is interpreted

Dominant axle and bogie frequencies can be obtained

Geophone produces a voltage proportional to velocity of the sensor

Knowing the response characteristics of the geophone the velocity can be computed

Integration of data leads to calculated displacement

• Note that we generally ignore the first and last axle movements in the displacement trace (start up transients)

Pendolino, next to feature

Estimate of at rest sleeper position

• Unusually high movement on inside of bend (V11) – possibly poor support conditions

Range of movement

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25

1110

Pendolino, At feature

• Some erratic movements, particularly for V6 and V5 which are the two geophones after the weld and the nearest to it

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25

1110

Pendolino, After feature

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25

1110

• Some variation in deflections but this is not uncommon and has been seen on other sites we have monitored (0.6 mm to 2 mm)

Pendolino, sleeper movements below Axle 15

Summary

• The Hodge Lane site shows some unusual features and it is possible that the nearby rail weld contributes to unusually complicated behaviour.

• However, at previous sites investigated (Weedon 2006) no rail welds were present within the migration features, so it would seem that migration cannot solely be associated with nearby rail welds.

• Further sites are needed for monitoring, ideally these would include sites where migration occurs but welds are not nearby

• Further monitoring at Hodge Lane planned• More sites needed

Thank-you and any questions?

Geophone references:

• Monitoring the dynamic displacements of railway track. D Bowness, W Powrie, A C Lock, J A Priest and D J Richards. Proceedings of the Institution of Mechanical Engineers Part F, Journal of Rail and Rapid Transit 221 (F1), 13-22, March 2007. ISSN 0954 4097. doi: 10.1243/0954409JRRT51. Awarded the IMechE John F Alcock Memorial Prize and the IMechE Thomas Hawksley Medal, 2008

• Determination of dynamic track modulus from measurement of track velocity during train passage. J A Priest and W Powrie. American Society of Civil Engineers Journal of Geotechnical and Geoenvironmental Engineering 135(11), 1732-1740, November 2009, ISSN 1090-0241. doi: 10.1061/_ASCE_GT.1943-5606.0000130