DTS: What is the Dynamic Track Stabiliser?

DTS: What is the Dynamic Track Stabiliser?

• In use since the 1980s on the UK infrastructure

• Self propelled on track machine

• Applies vibration to the track to ‘fluidise’ ballast

• When combined with a vertical load, enables better

ballast interlocking and reduced voiding.

• Research suggests consolidation achieved by DTS

is similar to 100,000 tonnes of ordinary line traffic.

DTS: Why do we use it?

• Better ballast consolidation > better lateral and vertical track support.

• Opportunity for higher speed hand-back

• Ineffective track support > Emergency Speed Restrictions (ESRs)

• Increased track stability through increased ballast consolidation

DTS: NR/L2/TRK/018 – The DTS Standard

August 1997

Major Changes:

➢ Re-write of Standard in its entirety.

➢ Full consideration of both Plain Line (inc. High Output) and S&C

➢ Provision for use in maintenance as well as refurbs and renewals

➢ Using on-site testing to validate data models to more accurately predict the

Zone of Influence of DTS

➢ Introduction of new TEF forms to identify structures and determine suitability for

DTS

(RT/CE/P/018)

S&C 90 Asset damage HP fracture switch

Visible failure of switch during

works

Loss or reduced function and potential

reduction in safety protection DTS

Passengers,

Workforce,

MOP 1 4 5 COP Form B Systems Component Certificate TEF 3203 (Issue 5)

S&C Refurb

WG 1 4 5

A condition assessment of all components and assets must be carried out prior to specifying

the use of the DTS. The assets must meet a minimum condition requirement as specified in

Appendix A. (DTS - CONSTRUCTION) 1 2 3

S&C 91 Loss of support train guidance DTS run out into unscoped site

DTS works outside scope

mileage and damages track or

structures

Potential for Train Derailment with

potential harm to train occupants and

those adjacent to the railway DTS

Passengers,

Workforce,

MOP 5 4 9

Compliance with:

NR/GN/TRK/7001/TWIT020 - How to plan a Dynamic Track Stabiliser S&C Refurb

WG 5 4 9

The mileages over which the DTS should operate should be clearly specified and assessed

for suitability for use of DTS, including the lengths of track where the DTS will be ramping

in/out. (DTS SCOPING) 5 1 6

S&C 92 Loss of support train guidance Bullhead keys vibrate loose

Potential for Train Derailment with

potential harm to train occupants and

those adjacent to the railway DTS

Passengers,

Workforce,


S&C Refurb

WG 5 4 9Certain layouts and track components are not suitable for use of DTS: Bullhead rail

(SCOPING DTS) 5 1 6

S&C 93 Asset damage E&P equipment damage



Passengers,

Workforce,

MOP 1 4 5 COP

Form E Electrification Certificate TEF 3203 (Issue 5)

NR/L1/NI/CP1010 Policy on working safely in the vicinity of buried services S&C Refurb

WG 1 4 5

Surface and buried cables are to be clearly marked up and removed, where possible, for the

duration of the excavation and re-ballasting works.

Points heating equipment should be removed.

1 2 3

S&C 94 Asset damage Switches that have been weld repaired



Passengers,

Workforce,


S&C Refurb

WG 1 4 5

A condition assessment of all components and assets must be carried out prior to specifying

the use of the DTS. The assets must meet a minimum condition requirement as specified in

Appendix A. (DTS - CONSTRUCTION) 1 2 3

S&C 95 Asset damage Damage to handpoints



Passengers,

Workforce,


S&C Refurb

WG 1 3 4Certain layouts, track and S&T components are not suitable for use of DTS:

• Hand points (DTS - SCOPING) 1 1 2

Track 96 Asset damage Damage to Plain Line components Force applied by DTS Fatigue/Equipment failure



Passengers,

Workforce,

MOP 3 4 7 COP

Existing RT/CE/P/018 Standard - Limited mention of specific components to be

controlled, also correspondance received from Pandrol and Vosslah that they

do not have any concerns surrounding the use of DTS and the effect that it

would have on their fastening systems.NR56/NR60 rail sections - evidence DTS WG 3 3 6

NR/L2/TRK/018/mod02 - Working Group discussed and approved -

Concrete sleepers (Cast-in housings, Converted F10 sleepers, with PR401A or e clips,

Converted F16 sleepers, with PR401A or e clips)

Wood sleepers (Screw-fastened Pandrol baseplates with approved pads and clips (e-clips

may be used in SG iron baseplates)) 3 1 4

Track 97 Asset damage Damage to asset by DTS working DTS zone not properly assessed

Damage to infrastructure (poor

track quality)



Passengers,

Workforce,

MOP 4 5 9 COP

Current limitations in RT/CE/P/018 set at 20m. To attempt to reduce numbers of

TSRs and improve handback speeds/ track quality, DTS scope is proposed

within closer parameters than 20m DTS WG 4 3 7

NR/L2/TRK/018/mod02 - Significant research done as part of DTS Standard to understand

the limit of zone of influence of DTS. Safety factor of 1.5 applied on top of existing limits in the

Standard. TEF 3274 to cover recording of where assets have/ have not been DTS'd, and

records category of asset being DTS'd. 4 2 6

Track 98 Asset damage

Asset deteriorates after initial

assessment but before DTS application Inspections out of date


track quality)



Passengers,

Workforce,

MOP 4 4 8 COP

Existing RT/CE/P/018 Standard - Requires review prior to DTS use, but with no

specific time periods assigned. DTS WG 4 3 7

NR/L2/TRK/018/mod02 - In discussion with the WG, new DTS TEFs shall be signed off at

nominally 3 years and 12 months out from the date work is due to commence.

If the work has not been completed within 12 months of final sign off, re-approval shall be

required. 4 1 5

Track 99 Asset damage Failure of obsolete componentry

DTS used on obsolete

components


track quality)



Passengers,

Workforce,

MOP 4 3 7 COP Not curently controlled in existing 018 Standard DTS WG 4 3 7

NR/L2/TRK/018 Standard - DTS shall not be used on track layouts with obsolete components.

Presence of obsolete fastenings should be recorded during scoping and plans to update

fastenings should be made. (SCOPE) 4 1 5

Track 100 Asset damage DTS used on asset which is unsuitable

Misunderstanding of 'Category'

in Standard Damage to infrastructure



Passengers,

Workforce,

MOP 4 4 8 COP

Existing RT/CE/P/018 Standard - Covers a broad understanding of the categories

and what to do in each case DTS WG 4 2 6

NR/L2/TRK/018 Standard - Further demonstrates the categories, plus the impact of TEF form

to accompany for proof of choise and recorded decision making. Structural assessment

reports Detailed structural examination reports shall be reviewed to confirm the

categorisation of each structure with respect to the operation of the DTS taking into account

the type of structure and defects present. 4 1 5

Structures 101 Asset damage Damage to asset by DTS working

DTS use on bridge/ culverts/

viaducts at natural frequencies Damage to infrastructure



Passengers,

Workforce,

MOP 3 4 7 COP DTS Standard (RTCE/018) prevents use at frequencies below 25Hz DTS WG 3 2 5New NR/L2/TRK/018 Standard includes this, plus guidance on standard working to use

frequencies above 33Hz 3 1 4

Track 102 Asset damage Damage to asset by DTS working

DTS causes baseplate shuffle in

S&C layout Damage to infrastructure



Passengers,

Workforce,

MOP 4 3 7 SRS

Currently best practise docuses on tamping standard and explores mitigation

by assessment of fastenings in line with TRK/001 but is not explicit with

requirement for DTS DTS WG 4 2 6

New NR/L2/TRK/018 Standard will require 'all track components are complete and in good

condition (including all bolted connections checked for security).

For guidance on condition, see NR/L2/TRK/001/mod05).

For specific guidance on condition of bearer ties, see (TRK/3406)' 4 1 5

DTS: NR/L2/TRK/018 – The DTS Standard

• HAZID Log connected to the Standard (over 85 hazards tracked to date,

still working through these…)

• Communication with existing DTS suppliers to ensure no duplication of

effort

• Discussion with key stakeholders to capture previous ‘Lessons Learned’

• Working Group sessions still ongoing to date

DTS: NR/L2/TRK/018 – Filling in the blanks

• Previous investigation has been done to understand the Zone of Influence

without the required conclusions.

• SETAN40 (Earthworks) – Focusses on the vertical effects (not lateral).

• High Marnham – Report considered inconclusive

• DTS of S&C – Purely S&C – Not ground effects.

• As a result, the Working Group agreed to conduct further testing of DTS,

with the intention to validate and calibrate a model with real-world testing,

which could then be used to simulate our requirements.

Work Scope

Literature review to understand the DTS

principles

Carry out site trials with using DTS and

measurement instrumentations

Develop and calibrate a 3D dynamic FEM to

using the trials data

Using the developed model, carry out a parametric study to understand the

effect of subgrade condition on the DTS influence zone

DTS: Testing (Site Selection)

• Predominantly driven by availability for both DTS machine and sidings.

• Grange Sidings, Stoke-on-Trent selected

• Previous DTS testing conducted here

• Well consolidated track (simulates ‘worst-case’

transmission path)

• Both F27 (MTCE) and G44 (REN) sleepers available

• DTS availability on site (thanks to Colas Rail)

• Good choice of roads in siding to choose from

DTS: Testing (Testing Protocol)

Vertical

Longitudinal

Lateral

DTS: Testing (Site Walkout)

• Identification of good testing locations

• Not near existing structures (to avoid interference)

• Preferable 1 x G44 and 1 x F27 (spot discrepancies)

• Good overall track condition, good ballast depth, good condition track

fastenings (replaced if poor/worn/missing)

DTS: Testing (Testing Protocol)

DTS: Testing

DTS: Modelling

DTS modelling

DTS inputs

Track Bed inputs

Compare vibration results with field data

DTS: Modelling

DTS: Modelling – model design



DTS: Modelling – simulation scope

DTS: Modelling – simulation runs

Simulation video

DTS: Modelling – results interpretation

n

m

DTS Unite

Stress

influence zone

m: Longitudinal distance

from the DTS centreline

to the position at which

the stress level equal to

the threshold

n: Lateral distance from

the DTS centreline to the

position at which the

stress level equal to the

threshold

DTS: Modelling – results vertical stress

-6

-4

-2

0

2

4

6

-10 -8 -6 -4 -2 0 2 4 6 8 10n(m

)

m (m)

DTS 5-soft DTS 5-stiff DTS 4-soft DTS 4-stiff DTS 3-soft

DTS 3-stiff DTS 2-soft DTS 2-stiff DTS 1-soft DTS 1-stiff

Vertical stress

DTS mode DTS loading Subgrade modulus (MPa) m (m) n (m) Area of influence zone (m2)

DTS 5Vertical load = 70bar

Frequency = 38Hz

6 8.5 4.6124

50 4.6 4.769


Frequency = 38Hz

6 5.3 4.066

50 4.2 4.458


Frequency = 33Hz

6 6.5 5.4111

50 4.7 4.363


Frequency = 28Hz

6 6.4 4.795

50 4.7 4.770


Frequency = 28Hz

6 5.2 3.964

50 3.9 4.252

DTS: Modelling – results vertical stress

DTS: Modelling – results vertical stress - soft soil

-20

-15

-10

-5

0

5

10

15

20

-20 -15 -10 -5 0 5 10 15 20n (

m)

m (m)

Max DTS vertical Light train vertical Heavy train vertical

DTS: Modelling – results vertical stress – stiff soil

-20

-15

-10

-5

0

5

10

15

20

-20 -15 -10 -5 0 5 10 15 20n (

m)

m (m)

Max DTS verticle Light train vertical Heavy train vertical

DTS: Modelling – results lateral stress - soft soil

-25

-20

-15

-10

-5

0

5

10

15

20

25

-20 -15 -10 -5 0 5 10 15 20n (

m)

m (m)

Max DTS lateral light train lateral Heavy train lateral

DTS: Modelling – results lateral stress - stiff soil

-25

-20

-15

-10

-5

0

5

10

15

20

25

-20 -15 -10 -5 0 5 10 15 20n (

m)

m (m)

Max DTS lateral light train lateral Heavy train lateral

DTS: Interpretation of the results

• Every DTS mode generates a different zone of influence

• The vertical stress influence can reach of up to 9m longitudinally and 5m

laterally (based on ‘worst case’ + 0.5kPa boundary conditions).

• The lateral stress influence can reach of up to 8m longitudinally and 19m

laterally (based on ‘worst case’ + 0.5kPa boundary conditions).

• In the longitudinal direction, the DTS stress influence is very similar to the

influence of running trains. However, this is not the case in the lateral

direction.

• The maximum influence is governed by the lateral stress from the DTS

DTS: Lessons learned

• The DTS ‘Zone of Influence’ appears larger than we originally anticipated

when referenced against the current limiting requirements from Structures

(STE).

• The research has given us useful information on stress vs. distance for the

DTS which we have never previously had.

• Structures may be more easily reviewed using these modelled stress

tables which will be found in the Standard. This should decrease

assessment time on required structures if DTS is planned.

• This research will be used to inform the requirements of the Standard (to

be published in 2020).

DTS: Next Steps

• Consultation with technical asset leads to further identify risk to structures

inside the ‘Zone of Influence’ currently defined.

• Micro-study - Management of low vs. high risk assets when using DTS

• Validation at DTS Working Group (early 2020)

• Standard publication using this modelling and feedback from the above

(NR/L2/TRK/018).

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DTS: What is the Dynamic Track Stabiliser?

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