STABLETRACK

Project description

The use of the CWR- “Continuous Welded Rail” Track has increased consistently worldwide thanks to its many advantages, over the conventional jointed rail track in terms of, for example, the reduction of maintenance costs or the increase of life cycle of track components.

Although the restriction of “free” movement of the CWR induces high thermal stresses (compressive forces) which, in combination with dynamic effects of the vehicles can affect the track stability and cause the buckling of the railroad track structure.

CWR track stability has been a subject in previous research activities and specific tools have been developed for evaluating the likelihood of track buckling. Nevertheless,

• The parameters and limit values affecting track stability are not described in detail,
• Difficulties are found in the use of the models developed, due to the unknown input parameters needed or because they are not opened to the potential users, the Infrastructure Managers,
• Monitoring techniques to ensure track stability are out of date,
• Related outcomes for maintenance practices (in track, S&Cs, bridges, tunnels…) are rarely defined,
• When safety assessment approaches are defined, at the end the IMs area left to fate; each IM must determine its own acceptable level of risk, which the consequent heterogeneity of criteria.

The project aims at analysing the key parameters affecting the CWR track stability, harmonizing the monitoring techniques and defining their “allowable” range of values. The calculation method for the prevention of track buckling will be updated and specific guidelines and recommendations (including design and maintenance requirements) intended to ensure the track stability and prevent the buckling of the track will be drafted based on the current track components and maintenance practices.

Additionally, the project will contribute to the reduction of incidents (and the consequent maintenance cost saving) due to track buckling.

Project objectives

The project aims at analysing existing thermal track buckling models and linear temperature rise techniques and identification of parameters for future models and protocols.

Project structure

• WP1 – Analysis of existing thermal buckling models, pro/cons, and identification of key parameters
• WP2 – Sleeper-Ballast Lateral Resistance evaluation techniques and related effects on the buckling temperatures calculation
• WP3 – Case studies for buckling temperatures evaluation of ballasted railway tracks

Project members

Administrator de Infraestructuras Ferroviarias

Bane NOR SF

Finnish Transport Infrastructure Agency

Infrabel S.A.

Österreichische Bundesbahnen

Prorail

Société Nationale des Chemins de fer Français

BAV (Swiss Administrator)

RFI

University of Napoles Federico II

UIC contact

For further information, please contact:

• Marcos Conceição

Deliverables

Analysis of Existing Thermal Track Buckling Models and LTR Experimental Techniques - Case studies for buckling temperatures evaluated of ballasted railway tracks

July 2023

View on shop.uic.org

Description

In this report, a sensitivity analysis carried out with some thermal track buckling models currently used by the members of the UIC technical group StableTrack and described in the framework of WP1 is presented. In detail, the buckling models considered for the comparative study are:

1. Meier +,

2. CWERRI + CW Safe – reference calculation program for UIC Leaflet 720 [1],

3. GP Pucillo – RFI,

4. Prud’homme, Janin.

The input parameters are summarized in Section ‎1, and for concrete sleepers they coincide with the data set included in the ÖBB regulation (Stabilitätsberechnung von Gleisen), see Table 5.

For wooden sleepers, instead, a different value from that reported in the ÖBB document was considered in terms of lateral resistance per meter of track of the sleeper-ballast system, namely 8.8 N/mm in place of 7.0 N/mm, as the CWERRI software does not allow to perform calculations with sleeper-ballast lateral resistance values below a certain threshold.

For the other models, the set of input parameters were calculated consistently (see Table 1,Table 4, Table 6 and Table 7).

It is important to specify that, to carry out the calculations under the same conditions with all the models, the possible presence of the peak lateral resistance was not considered, i.e. no compaction effect on the sleeper-ballast lateral resistance curve (see Figure 1), as this characteristic is an input parameter only in the GP Pucillo-RFI model and in CWERRI software.

Finally, the results of the calculations are exposed in tabular and graphical format in Section ‎2.

Author UIC
ISBN 978-2-7461-3299-3
Pages 18

Benchmark for UIC Stabletrack Group - Information of European IMs

July 2023

View on shop.uic.org

Description

The information given in the following tables, is only supplementary information to the current track design standards and regulations, operational temperature ranges and buckling statistics related to CWR track and gives a vision of the variety existing concerning that. It is important to remember that the weather conditions as well as the maintenance strategies are very different from any country to another and sometimes are also different along the same country, from the north to the south.

Auteur UIC
ISBN 978-2-7461-3272-6
Pages 18