This IRS contains recommendations regarding the use of Under Ballast Mats.
The IRS covers the field of application for Under Ballast Mats (UBM), defines the technical and physical parameters to consider for UBM acceptance and a guide to good practices when installing the UBM as well as the limitations for their use.
The IRS completes the European standard EN 17282:2020 "Railway applications - Infrastructure - Under ballast mats" in order to recommend acceptance criteria for the different test of this standard.
The IRS also includes a discussion of the insertion of other elastic components in the track, such as soft rail pads and Under Sleeper Pads (USP).
It integrates in full or in part the following UIC leaflets:
- UIC Leaflet 719-1
It aims to complement the following standards:
- EN 17282:2020: Railway applications - Infrastructure - Under ballast mats, 2020

An International Railway Solution (IRS) is a document drawn up by consensus and applied on a voluntary basis which aims to facilitate and harmonise railway operation.
IRSs are gradually replacing UIC leaflets.
Members of the International Union of Railways (UIC) participate in the creation of IRSs, of which they benefit in full. Furthermore, marketing to railway stakeholders contributes to the sharing and harmonisation of good practices, in accordance with UIC's primary goal.
While IRSs do not have the force of law, they are created and published in a professional manner and with technical approval on the basis of UIC procedures, and have full technical legitimacy in the railway sector.
The "General application" section constitutes the heart of the IRS and contains the working group's expertise applicable in the broadest manner. The addition of a "Specific application" aims to cover factors specific to a region, a type of service, etc.
Some provisions shall be implemented in all cases to ensure correct application and maintain the system's cohesiveness. Certain operational circumstances require that specific provisions be systematically applied by all users of the document.
For the purposes of understanding, the user acknowledges that the expression of:
- obligation indicates requirements to be respected in order to comply with the expertise expressed in the document (usually "shall");
- recommendation indicates options that are favourable but not essential （usually "should"）；
- permission indicates options that are recognised but without consequence (usually "may");
- capacity indicates possibilities from a technical standpoint and not permissions or probabilities (usually "can").
Obligation, recommendation and capacity can be expressed in the negative to indicate prohibiting, non-recommendation and incapacity.
If applicable, notably for the purposes of compliance with a UIC approval, passages that are recommended or mandatory for the cohesiveness of the system will be accompanied by the letters "R" and "MCS" respectively.
This IRS reflects the following UIC working group expertise:
Ad-hoc working group for the update of UIC Leaflet 719-1, directed by the TEG (Track Expert Group).
It integrates in full or in part the following UIC leaflets:
- UIC Leaflet 719-1: "Recommendation for the use of Under Ballast Mats, UBM", Ed. no. 1, June 2011
It complements the following standards:
- none
The following IRSs constitute a complementary series:
- none

Foreword 1

Executive summary 3

Field of application 4

Reference documents 5

Abbreviations and Symbols 8

1 - Introduction 11

2 - Purpose of laying UBM 13

2.1 - UBM for vibration reduction and ground-borne noise 15

2.2 - UBM for ballast protection and substructure protection 18

2.3 - UBM on existing structures with reduced ballast thickness 18

2.4 - UBM for transition zones 19

2.5 - Limitations 20

      2.5.1 - UBM and ballast destabilisation 20

      2.5.2 - Possibility of combining UBM with USP 20

      2.5.3 - Possibility of combining UBM with XPS plates 21

      2.5.4 - UBM in small-radius curves 21

      2.5.5 - UBMs and braking forces 22

      2.5.6 - UBMs and stabilisation 22

3- Requirements for qualification and routine tests - General 23

4 - Mechanical and physical properties 26

4.1 - Generality about bedding modulus 26

      4.1.1 - Static bedding modulus 26

      4.1.2 - Dynamic bedding modulus 29

4.2 - Static horizontal bedding modulus (Shear bedding modulus) 38

4.3 - Fatigue (Fatigue test with ballast and Fatigue test with GBP) 39

      4.3.1 - Recommendations for Fatigue test of UBM in ballast box 39

      4.3.2 - Recommendations for Fatigue test of UBM with GBP (long term variation of bedding modulus) 40

4.4 - Compression set test (Long term deformation) 40

4.5 - Ageing 41

      4.5.1 - Recommendations for Water resistance and Freeze-thaw resistance test 42

      4.5.2 - Recommendations for Ageing test with high temperatures 43

      4.5.3 - Recommendations for Water absorption capacity according to DIN 45673-5 43

      4.5.4 - Test recommendations for Resistance to chemical agents 44

      4.5.5 - Test recommendations for resistance to fire 45

      4.5.6 - Test recommendations for resistance to Hydrocarbons 46

      4.5.7 - Test Recommendations for resistance to Ozone 46

4.6 - Dimensions and masses of UBM 46

4.7 - Environment and end of life 47

4.8 - Tensile and tear strength 47

4.9 - Test in track (service test & installation test) 47

4.10 - Vertical Track Stiffness and Lateral Track Resistance in the Laboratory 50

4.11 - Recommendations for Routine tests 51

5 - Installation conditions and storage 52

Appendix A: Noise and vibration caused by the passage of trains 53

A.1 - General 53

A.2 - Characteristics 53

A.3 - Calculation of transmitted force and resonance frequency of track with UBM 55

Regulatory listing 57

Bibliography 60

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