Non-destructive assessment of soft changes in the rail head of heavy duty glued insulated rail joints using Brinell hardness methods

A new design of Glued Insulated Rail Joint (GIRJ) is available to the rail industry from Thermit Australia Pty Ltd. It is a heavy-duty (HD) design over existing GIRJ steel joint bars and has an objective to improve upon and strengthen existing designs for heavy haul railway applications. The main structure of the steel joint bar has an increase of strengthened steel across the centre structure of the two fishplate bars. The new design of HD GIRJ is being trialled on Aurizon’s Blackwater system for singular performance attributes and against the commonly used thinner older design of GIRJ. This paper has focused on the testing and evaluation of the soft changes in the rail head, observing the hardness reactions of both different types of joint. The new HD joint bar design changes in Brinell Hardness has been compared against the existing older thinner type joint bar with the aim being to evaluate long term sustainability of HD GIRJs in a modern heavy haul railway. The methodology used to obtain the collated data during this study has been completed whilst the insulated rail joints have been working under live conditions in a heavy haul railway environment over an 18-month period at differing locations on the rail crown. The various joints were examined on a regular basis throughout approx. 18 months of evaluations using a portable Brinell hardness tester to record details of changes in the rail head. Measurements were recorded and imported into a Power Bi system that displayed readings of hardness changes of each test site over time and at 18 separate locations of the rail head. The results from the monitoring of Brinell hardness testing that have been completed are available from three separate locations where two different joint designs work on adjacent rails to ensure the continued safe running of revenue train services. The testing results have been obtained and evaluated from three sites including one which has two HD GIRJs installed (one on either rail) and two further sites which have an older and thinner design of GIRJ adjacent to a new strengthened HD GIRJ design. Data revealed that the field side of the rail crown increased in hardness at a faster rate than the locations on the rail head at the centre and running side. It was also observed that rails carrying heavier loaded coal trains produced harder Brinell readings at a faster rate than roads which were pre-dominantly carrying lighter unloaded train services. Post-processing of the data that has been obtained to date has allowed recommendations to be made for the improvement of track design reliability and track maintenance procedures at the locations of track that have had joints installed.