VEHICLE/UNDERLINE
BRIDGE COMPATIBILITY
ASSESSMENTS
Gauging & Loading Seminar, London
4 th November 2015

AGENDA
BACKGROUND PROJECT SCOPE
INTEROPERABILITY
BRIDGE COMPATIBILITY
ASSESSMENT PROCESS
PROJECT DELIVERABLES

INTRODUCTIONS
MATTHEW KYNOCH
Project Manager
DAVID GIBSON
Task Manager & Lead Author
BRIAN STEWART
Bridge Dynamics Specialist

BACKGROUND
 Studies have been conducted on the compatibility of passenger vehicles and railway bridges across the European Union
 Current and future train architectures obtained to future proof bridge design requirements
 Implication is that design requirements for infrastructure (particularly bridges) may need to be enhanced to accommodate faster and heavier vehicles
 Understand implications on potential revisions to GE/RT8006 & EN 1991-2

BACKGROUND
 Key requirements of vehicle/underline bridge compatibility assessments:
–
Structures to have sufficient load carrying capacity for the safe & serviceable passage of the proposed rolling stock formations
– The bridge structures are to have an appropriate dynamic response to ensure that the resultant vibrations are not excessive to avoid the risk of ballast instability

BACKGROUND
 What are the risks associated with ballast instability?
Cause
Excessive vibrations due to the operation of high speed trains
Effect
Loss of ballast interlock
Void formation
Loss of sleeper base
/ side friction & end restraint
Loss of sleeper base
/ end friction & side restraint
Consequence
Loss of vertical support
Loss of lateral support
Loss of longitudinal support
TRAIN
DERAILMENT

BACKGROUND
 Vehicle characteristics that dictate dynamic behaviour
– Variation of loading along length of train
– Axle loads
– Axle/bogie spacing & coach length
– Operational speed

BACKGROUND
 Bridge characteristics that dictate dynamic response
–
Structural form
– Span
– Natural frequencies
Material Key
Analysis: Analysis 1
Cross-beam Mild Steel Ungraded (N m kg C)
Main Girder Mild Steel Ungraded (N m kg C)
Rail - 60kg-m
Bar-to represent ballast
Steel Plate-Mild Steel Ungraded (N m kg C)-with ballast
Rail Bearer- Mild Steel Ungraded (N m kg C)
–
–
–
Mass
Stiffness
Damping
THY
THY
THY
THY
THY
THY
THY
THY
THY
THY
THY
THY
THY
Y
THY
Z
THY
X
THY
THY
THY
THY
THY
THY
THY
THY
THY
THY
Span
THY
THY
THY
THY
THY

PROJECT SCOPE
 Further understand compatibility of current and future rolling stock with real bridges to avoid the risk of ballast instability by:
–
Establishing current industry
‘state of the art’ knowledge on ballast stability
– Enhancing the understanding of GB bridge population and bridge types potentially sensitive to dynamic induced vibrations
–
Advancing the understanding of influence of bridge skew , torsion and floor vibration with respect to dynamically induced vibrations

PROJECT SCOPE
Understanding ballast behaviour
Historical
Design &
Assessment
Criteria
Today
Literature/ industry review
UIC, DB &
WCML Project
Development of
DEM as early research tool
Shake table tests
Dynamic triaxial tests
Limited advancements with shake table work
Site monitoring
Challenges to existing criteria limited

PROJECT SCOPE
 Establish representative GB bridge population

PROJECT SCOPE

PROJECT SCOPE
 Establish representative GB bridge population
 Parametric studies to simulate dynamic response of representative GB bridges

PROJECT SCOPE
Material Key
Analysis: Analysis 1
Cross-beam Mild Steel Ungraded (N m kg C)
Main Girder Mild Steel Ungraded (N m kg C)
Rail - 60kg-m
Bar-to represent ballast
Steel Plate-Mild Steel Ungraded (N m kg C)-with ballast
Rail Bearer- Mild Steel Ungraded (N m kg C)
THY
THY
THY
THY
THY
THY
THY
THY
THY
THY
THY
THY
THY
Y
THY
THY
Z
THY
X
THY
THY
THY
THY
THY
THY
THY
THY
THY
THY
THY
THY
THY
THY
05/08/2015
Main Girder Accelerations for Real Bridges - Filler Type
All Square and Skew Spans
Centre Girder Going Thru' Centre of Deck - 16.8m Span
Real Trains Envelope
0.6
0.57
0.54
0.51
0.48
0.45
0.42
0.39
0.36
0.33
0.3
0.27
0.24
0.21
0.18
0.15
0.12
0.09
0.06
0.03
0
0
16.8m Square
16.8m 45 Deg - Acute
16.8m 45 Deg - Obtuse
16.8m 20 Deg - Acute
16.8m 20 Deg - Obtuse
20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320
Speed (kph)
Material Key
Analysis: Analysis 1
Iso1 (Steel UK Network Rail)
Rail - 85kg-m
Steel - Massless
Manipulated Steel - 1/2 inch Floor Plate
Y
Z
X

PROJECT SCOPE
 Establish representative GB bridge population
 Parametric studies to simulate dynamic response of representative GB bridges
 Understand implications of current and future rolling stock architecture on GB bridge population
 Enhance existing bridge compatibility assessment process

BRIDGE COMPATIBILITY ASSESSMENT
SPEED
EXISTING
ROLLING
STOCK
FUTURE
ROLLING
STOCK
SAFE &
SERVICEABLE
PASSAGE
OVER
BRIDGE
BRIDGE
FORM
CRITERIA

BRIDGE COMPATIBILITY ASSESSMENT -
ROLLING STOCK
 Current and future rolling stock architecture considered
– Existing ‘comparator’ trains
– Reference Load Models (defined in T988) covering range of GB future train architectures
– Proposed high speed trains (e.g. IEP)
– High Speed Load Models (BS EN 1991-2) for new bridge design
– MU Classes (defined in EN 15528: 2015) for classifying multiple units

BRIDGE COMPATIBILITY ASSESSMENT -
BRIDGE FORM
 Established representative GB bridge population
 Reviewed bridge characteristics and identified parameters likely to influence dynamic performance
 Parametric modelling undertaken to understand influence of key characteristics
 Understand likely compatibility with rolling stock considered

BRIDGE COMPATIBILITY ASSESSMENT -
ACCEPTANCE CRITERIA
 Current acceptance criteria builds upon
European experience
 Extensive work undertaken by Network Rail to refine acceptance criteria:
–
Route clearance studies including dynamic modelling and bridge monitoring
– R&D including shake table tests at BAM University
 Potential to refine criteria further in the future (through further R&D)

COMPATIBILITY ASSESSMENT PROCESS
New rolling stock proposed operating at >90mph
Stage 1
Vehicle clearance
Parametric study considering generic bridge types
Compare to criteria and identify ‘at risk’ types & spans
Stage 2
Bridge specific clearance
Undertake simple analysis e.g. nonunique, low skew
Compare to criteria and identify need for detailed analysis
Stage 5
Mitigation measures
Stage 4
Bridge site monitoring
Stage 3
Bridge specific detailed analysis

COMPATIBILITY ASSESSMENT PROCESS
Stage 1
Vehicle clearance
Compare proposed rolling stock to RLM parameters
Parametric study considering generic bridge types
Compare to criteria and identify ‘at risk’ types & spans
Train architecture
Train signature
Potential to negate requirement for parametric study for proposed rolling stock

COMPATIBILITY ASSESSMENT PROCESS
Stage 2
Bridge specific clearance
Undertake simple analysis e.g. nonunique, low skew
Compare to criteria and identify need for detailed analysis
Development of guidance tools
Potential to negate requirement for bridge specific work

COMPATIBILITY ASSESSMENT PROCESS
Stage 3
Bridge specific detailed analysis
Rules for simple analysis for greater bridge type coverage
Bridges that do not pass simple analysis
Highly skewed bridges/unique novel bridges
Bridge form
Bridge characteristics e.g. aspect ratio
Potential to reduce requirement for detailed or complex
2D/3D modelling analysis

INTEROPERABILITY
 Infrastructure TSI defines target minimum bridge requirements for multiple units in terms of dynamic bridge loading characteristics of vehicles
 Opportunity in the future to define interface between the dynamic loading of vehicles, vehicle characteristics and bridge capacity
 Understand compatibility of train manufacturers v train architecture aspirations with existing bridge infrastructure
 Recommendations will be made for methodology to close out open points

PROJECT DELIVERABLES
 Recommendations on the compatibility of current and future rolling stock on the GB bridge network
 Enhanced knowledge of GB bridge infrastructure, characteristics and dynamic performance
 Enhancements to the existing vehicle/bridge compatibility assessment process

PROJECT DELIVERABLES
 Guidance Tools for assessment and design
(e.g. charts)
 Recommendations on the development of simple rules to negate requirement for complex bridge analysis during compatibility assessments
 Commentary regarding the appropriateness of current Load Models such as HSLM used for bridge design with the Eurocodes

PROJECT DELIVERABLES
 Recommendations for R&D to challenge and potentially refine acceptance criteria used within compatibility assessments
 Methodology for closing open points within
Infrastructure TSI

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