Rail Inspection Event draws record crowd

Report of the recent 9th Technical Seminar

IoRW events are always well supported, but the recent event in Derby on 'Developments in rail inspection' was something special with over 120 people attending.

Riverside conference centre

Fortunately the Riverside Conference Centre was big enough to cope and delegates were able to enjoy a full day of technical presentations in comfort, under the able chairmanship of Dr Jay Jaiswal of Corus Rail Technologies. Brian Whitney of Network Rail set the scene with a presentation on Network Rail's preventative track integrity initiatives. The aim is to reduce the number of rail breaks to a consistent low level. Steps to achieve this include:

  • Improving defect management.
  • Increasing frequency of vehicle based inspection and monitoring.
  • Introducing new inspection and non-destructive testing technology.
  • Improving rail management, including grinding.

This has involved considerable investment over the last five years and the results are extremely encouraging. Significant reductions in rail breaks have been achieved, with the number continuing to fall year on year to last year's total of 317.

With regard to the specific activity of weld inspection, Ian Davison gave an account of Network Rail's requirements in relation to aluminothermic welds. Inspection of completed welds is carried out firstly by the welder and subsequently (within 30 days) by a weld inspector. The acceptance criteria are detailed in specification NR/SP/TRK/032. Competence of inspectors is key and, in the near future, assurance of competence will be enhanced by the introduction of annual in-track assessments and two-yearly out-of-track re-certification.

The acceptance criteria have recently been revised to take account of the likelihood of failure from a particular defect type and the consequences of failure, related to line speed.

Inspection data are being gathered and analysed to help shape future working methods and welding process developments.

Mick Wainwright of Thermit Welding (GB) and Gerry Dineen of First Engineering presented the work they had done to develop harmonised training materials for rail welding inspectors. They tracked the improvements that have been made to weld inspection practices since the derailment due to a broken weld at Bushey in 1980. The current training package was a significant milestone in this process of evolution, and made use of the most up-to-date training media.

Fig.2. Weld inspection - equipment changes

a) Equipment circa 1980 b) Equipment 2006
Weld inspection Weld inspection

The welding inspector course is of three days' duration and covers: requirements for inspection; method of inspection; weld defects; verticality and geometric tolerances; final profile grinding and reporting. At least three hours is spent on practical weld inspection and the course concludes with theory and practical examinations.

Discussions on the implementation of the course are currently underway with Network Rail.

Non-destructive testing (NDT) is widely used on the rail infrastructure on plain rail, on rail refurbishment and occasionally on welded joints. Sam Broujeni of Balfour Beatty Rail Technologies outlined the various NDT methods that are used: magnetic particle testing (MT), liquid penetrant testing (PT), alternating current field measurement (ACFM) and ultrasonic testing (UT). The main method is UT and there are currently 12 approved procedures. The vast majority is still done manually although this is augmented by complex train-borne, road/rail or cart based UT systems. Particular mention was made of the 'U6' which is a tandem probe ultrasonic technique used for the testing of the fusion faces of aluminothermic welds. The technique is not new but appears to have come back into favour following a period of low usage.

Two special rail testing techniques were mentioned: ACFM testing for gauge corner cracking and head checking; and the testing of in-street grooved rails.

Fig.3. Special rail testing by ACFM
Special rail testing by ACFM

The NDT theme was continued by Archie Crawford of Network Rail. He focussed on operator training and certification aspects and on Network Rail's evolving requirements. For UT, specification NR/SP/TRK/1110 had been issued and for MT and PT the specifications were in final draft form. A specification was also being prepared for guided wave UT. MT and PT are used during defect removal, for testing of MMA weld repairs. MT can also applied to prepared rail ends and for final weld inspection of aluminothermic welds.

Training modules and associated examinations for grinders, welders and for Level 1 NDT operators (required for final inspection of defect removal or welding) have been developed.

High speed ultrasonic rail testing, using Sperry Rail International equipment, was the subject of Bob Crocker's presentation. After describing the various types of rail defects that can occur both in welds, joints and in plain rail, he went on to describe the equipment and techniques currently in use. The objective is to test frequently, find everything and operate a pro-active defect management strategy. The latter is facilitated by accurate GPS positioning and a web-based database of defects.

Fig.4. Sperry train mounted roller search unit (RSU)
Sperry train mounted roller search unit

Rail defect management was the topic of Gareth Evans from Corus Rail Technologies. Higher demands in terms of volume of rail traffic and safety were creating challenges for infrastructure management. Technology developments were required to meet the challenges and these included:

  • New inspection systems and procedures.
  • Improvements in the accuracy and consistency of defect reporting.
  • Improve understanding of root causes.
  • Robust, risk-based actions.

The Corus/UIC web-based rail defect management system was described. This allows comprehensive defect data to be entered locally via a hand-held device. This has the advantage of ensuring high quality data, saving time (single operation) and a configurable user interface. It uses an expert system which ensures accurate classification, and improved decision making by the inspector. The internet-based master database allows 'real time' management of faults and improved management-level decision making.

With regard to root causes, extensive work has been carried out to better understand the significance of defects by means of the Corus critical defect model. Applying this model gives a clearer understanding of risk and therefore more informed decisions about minimum actions for correction.

Throughout the day there were active discussion periods covering the topics presented from both the technical and economic points of view. There seemed to be a consensus that, despite all the significant and beneficial technology improvements, the need for competent people remained paramount.

Eur Ing Tim Jessop
IoRW Executive Officer