Office of the Rail Regulator
Broken rail report commissioned by Regulator & HSE shows way forward
keywords: click to search
Office of the Rail Regulator
Phrases in [single square brackets] are hyperlinks in the original document
Phrases in [[double square brackets]] are editorial additions or corrections
Phrases in [[[triple square brackets]]] indicate embedded images or graphics in the original document. (These are not usually archived unless they contain significant additional information.)
Broken rail report commissioned by Regulator & HSE shows way forward
type Press release
The publication today of an independent report commissioned by the Rail Regulator and the Health & Safety Executive (HSE) in August 2000, highlights the way forward for Railtrack's safe management of broken and defective rails. The report remarks on the traditional tolerance in Britain of relatively high levels of broken rails compared with other countries and urges Railtrack to put into place a more robust and thorough system for improvement.
Rail Regulator, Tom Winsor today said:
"This is a balanced and constructive report that should be welcomed by all parties. We will be studying it carefully. Railtrack has been taking many of the actions necessary to reduce the number of broken rails and already has in hand a number of the recommendations made in this report. The report does however demonstrate that there are other methods, actions and processes available to Railtrack that could contribute to greater reductions in broken rails than the company is currently forecasting."
The Rail Regulator and HSE consider that Railtrack must urgently examine and develop improvements, particularly in respect of:
how rails are inspected and tested for defects, and in particular the extent, frequency and methods of ultrasonic testing;
how rail defects can be better identified and recorded;
how identified rail defects can be better managed; and
its own guidelines and standards for dealing with defects that are identified within rails. Total numbers of defects in track should be reduced.
The report has been made available to the team investigating the derailment at Hatfield.
Vic Coleman, Chief Inspector of Railways said:
"HSE welcomes this report as it provides useful and comprehensive information on broken rails. We will carry on working closely with the Rail Regulator in continuing to develop a strategy for reducing and managing broken rails on the network. HSE will also monitor carefully Railtrack's proposals against their duties as infrastructure controller under health and safety legislation."
The Rail Regulator and the HSE will be writing to Railtrack asking it to respond to the TTCI report and to take the necessary action. It should also explain how this interacts with the national track recovery plan.
Mr Winsor concluded:
"Safety is our chief concern and I believe firmly that the network can be maintained and improved at the same time as delivering a high quality, high performance service."
ORR Press enquiries: Sue Daniels/David Davies 020 7282 2130/2007 Out of hours pager: 07659 127303 HSE Press enquiries (journalists only): Scott McLean 020 7717 6918 HSE out of hours: 020 7928 8382 HSE website: www.hse.gov.uk.
TTCI Rail Failure Assessment in the UK - Acrobat PDF.
The Joint Statement and Executive Summary follow the Notes to Editors.
NOTES TO EDITORS
1. ORR and HSE commissioned a report in August 2000 from Transportation Technology Center Inc of Pueblo, Colorado following the Regulator's long-standing concern over the number of broken rails.
2. TTCI is a subsidiary of the American Association of Railroads and has internationally acknowledged technical expertise in the area of broken rails. Their final report was received by the Rail Regulator on 2 November 2000 and copies were sent to Railtrack on the same day.
3. The executive summary of the TTCI findings is attached along with a joint ORR and HSE statement.
4. The TTCI report: Rail Failure Assessment for the Office of the Rail Regulator will be available on the ORR Website: www. email@example.com. Hard copies are available on request from the ORR Librarian, Sue MacSwan, 1 Waterhouse Square, 138-142 Holborn, London EC1N 2TQ.
Joint statement by the Rail Regulator and the HSE about TTCI's report on managing broken and defective rails
1. The TTCI final report was received by the Rail Regulator and HSE on 2 November 2000, and copies were sent to Railtrack on the same day. Evaluation of the report is continuing, but the Rail Regulator and the HSE have already identified the following main points from the report.
(a) the mix of traffic and the permissible axle loadings on Britain's railways has led to a traditional acceptance of relatively high numbers of broken rails compared with other countries, and Railtrack has until recently continued this practice;
(b) however, there has been a rising trend in the number of broken rails through the 1990s, with a particularly sharp increase in 1998-99 being followed by only a small reduction in 1999-2000. The trend is attributed to several possible factors. A slowing down of the rate of rail replacement by British Rail and Railtrack in the early to mid 1990s has been followed by significant traffic growth since 1994/95. Railtrack believes that rolling stock design and maintenance standards may be important factors, whilst TTCI has also concluded that deterioration in track geometry and Railtrack's current rail inspection methods have also contributed to the recent trend;
(c) Railtrack has been taking many of the actions necessary to reduce the numbers of broken rails, and has told the Rail Regulator and the HSE that it already has in hand a number of the recommendations made by TTCI. The report acknowledges that in the early part of 2000-01 there was a significant reduction in the number of broken rails. However evidence within the report suggests that there are other methods, actions and processes available to Railtrack which could contribute to greater reductions than the company is currently forecasting;
(d) Railtrack has continued the previous British Rail practice of accepting large numbers of rail defects within the rail network. The safe management of this situation requires a robust and thorough system for inspecting, identifying, reporting, monitoring and auditing the actions being taken by Railtrack and its contractors. The report is critical of the systems and processes currently in place, and the Rail Regulator and the HSE consider that Railtrack must urgently examine and propose improvements, particularly in respect of
(i) how rails are inspected and tested for defects, and in particular the extent, frequency and methods of ultrasonic testing;
(ii) how rail defects can be better identified and recorded;
(iii) how identified rail defects can be better managed.
(e) Railtrack told TTCI that it had recognised the importance of these issues, and the Rail Regulator and the HSE consider that the TTCI report confirms the urgent need for improvement;
(f) Railtrack must also urgently examine its own guidelines and standards for dealing with defects that are identified within rail, particularly in the context of recent traffic growth. The TTCI report recommends that Railtrack should maintain a central record of all defects left in track, and that since large numbers in this category are likely to increase the risk of broken rails, total numbers of defects in track should be reduced;
(g) TTCI suggests that the average age of the rail on the Railtrack network is increasing, a trend that is bound to increase the risks of fatigue failure. Railtrack's assumptions about rail life may have led it to plan for relatively low levels of replacement over the next few years, although it has always acknowledged that a substantial peak of rail renewal would be required in future. Given the apparently very high number of rail defects currently believed to exist within the network, we believe that Railtrack should re-examine its assumptions about rail life;
(h) In doing so, Railtrack must also consider TTCI's finding that rail installed within the last 10 years appears to suffer a higher rate of breakage than older rail. We are seeking Railtrack's analysis and explanation for this;
(i) the tragic accident at Hatfield occurred whilst the report was in preparation, and it inevitably raises many issues that are likely to be of relevance to the inquiries into the circumstances of the accident. The preliminary conclusions indicate a particular type of rail fatigue known as gauge corner cracking to be its primary cause. It is acknowledged that this phenomenon is also increasing on other rail networks around the world, and that a great deal of international research is going into understanding its causes;
(j) such rolling contact fatigue defects require thorough investigation of all aspects of the wheel-rail interface. Railtrack believes that vehicle design and maintenance standards may be a contributory factor to the emergence of gauge corner cracking. The industry must collectively examine all possible factors, with Railtrack taking a leading role; this must include participation in international studies;
(k) the report makes reference to the industry processes by which infrastructure work is planned. Railtrack, with its customers and its contractors must ensure a proper balance between undertaking essential maintenance and renewal work on the network, and doing so in a timely manner, whilst it also ensures that the work is properly planned to meet the needs of passengers and freight customers;
(l) in conjunction with each of these considerations, Railtrack must also urgently review the resourcing of its rail management processes, to ensure that the necessary level of specialist technical expertise is available.
3. The Rail Regulator and the HSE will be writing to Railtrack asking it to respond to the TTCI report and to take the necessary action. It should also explain how this interacts with the national track recovery plan.
Railtrack, a public limited company that owns and operates the mainline railway network in Great Britain, had a significant number of broken rails along its network during 1998/1999 and 1999/2000. These increases, together with continued restatements by Railtrack of future broken rail predictions, has caused the Office of the Rail Regulator to question whether Railtrack is meeting its network license obligations to manage the rail infrastructure. Her Majesty's Railway Inspectorate (HMRI) is also concerned about the number of broken rails, which are believed to represent a risk to safety. Accordingly, Transportation Technology Center, Inc. (TTCI), Pueblo, Colorado, USA, was asked by the Rail Regulator to undertake a study to determine whether:
* Railtrack's activities in this area are consistent with its license obligations; and
* These activities are reducing the safety risks arising from broken rails to the lowest reasonably practicable level.
To fulfil this study, TTCI has met with staff from the Rail Regulator and HMRI to better understand their concerns. TTCI has met with Railtrack to gain a fuller understanding of the historic numbers of broken and defective rails, the types of defects causing problems, current rail inspection procedures used by Railtrack, and the actions that Railtrack is taking to reduce the numbers of broken rails. TTCI has also approached other railways to determine inspection procedures and broken and defective rail numbers with which to compare Railtrack's performance. Key points that have emerged from this study are given below.
Historic Numbers of Broken Rails
For over 30 years - 1969 to 1999/2000 - the number of broken rails on Railtrack (British Rail before 1994) has stayed almost constant at an average of 767 per year and a standard deviation of 128. The 1998/1999 figure of 952 breaks and the 1999/2000 figure of 918 breaks represent increases of 1.46 and 1.19 standard deviations, respectively, over the 30 year average. It cannot be discounted, therefore, that the high figures for these two years are statistical fluctuations rather than symptoms of a genuine worsening of rail condition.
Historic Numbers of Defective Rails
Over the same 30-year period, the numbers of defective rails removed per year has increased almost linearly from about 1,250 in 1969 to about 8,700 in 1999/2000, approximately a 600 percent increase.
Recent Numbers of Broken and Defective Rails
There has been a general rising trend of broken and defective rails removed through the 1990s, culminating in high levels of broken rails in the last two years. It is therefore assumed that the recent high levels of broken rails are not simply a statistical fluctuation.
Broken and Defective Rail Comparisons with Other Railways
In terms of the number of defective rails removed per year per track mile, Railtrack removes about the same numbers of defects as most of the comparison railways. In terms of broken rails removed per year per track mile, Railtrack appears to perform significantly worse than the comparison passenger railways, and at a similar level to typical North American freight railways that carry much higher axle loads.
Rail Inspection Comparisons with Other Railways
The rail inspection intervals used by Railtrack are broadly in line with those used by other railways. However, while almost all of the comparison railways are committed to rail inspection using sophisticated ultrasonic test vehicles, Railtrack has been committed to manual ultrasonic inspection techniques. TTCI believes this has inhibited the adoption of ultrasonic probes that can search for defects to the side of the railhead centre, and the implementation of modern digital ultrasonic signal processing techniques for better defect identification. Railtrack is now re-adopting test vehicles for ultrasonic inspection. This report gives details of emerging technologies that may eventually offer improved rail inspection.
Reasons for Recent High Numbers of Broken Rails
This report puts forward possible reasons why the number of broken rails rose through the 1990s. These include:
o Falling levels of rail renewals over the last 30 years.
o The recent increased reliance on manual ultrasonic rail inspection.
o A worsening of track quality and a possible increase in wheel irregularities, both of which lead to higher dynamic forces.
o Increasing levels of traffic, which may not have been followed by increased inspections, and have not been accompanied by revised minimum action criteria for defect removal.
o The possible acceleration of rolling contact fatigue as a result of the introduction of bogies with higher wheelset yaw stiffness.
Actions Taken by Railtrack to Reduce Broken Rail Numbers
Railtrack has taken many initiatives to reduce broken rail numbers. These include:
o Better reporting of the causes of broken rails.
o Management processes to focus on reducing broken rail numbers.
o The production of defect and break maps to identify cluster locations.
o The re-introduction of improved test vehicles for ultrasonic rail inspection.
o The development of Zone and maintenance contractor plans to decrease broken rail numbers.
o The adoption of remedial techniques (such as rail grinding and cold bolt-hole expansion) to reduce defect levels.
The numbers of broken rails in the first seven periods of 2000/2001 are approximately 25 percent down on the 1998/1999 and 1999/2000 averages for the same periods. This may indicate that Railtrack's actions are beginning to bear fruit.
1. Railtrack should consider moving to a risk-based approach to the management of broken rails. This should include an assessment of the cost/benefits of early removal of defective rails and whether current levels of rail renewal are adequate.
2. Railtrack should maintain a central database of defects judged suitable to be left in track and should assess the safety risk from these defects. Total numbers of defects in track should be reduced.
3. Railtrack should re-assess the minimum action criteria specified when defective rails are found and consider moving from current time-based criteria to tonnage-based criteria, and whether current inspection intervals are suitable for the increased traffic.
4. Railtrack should pursue the introduction of automatic ultrasonic inspection methods using digital signal processing techniques and increased probe arrays to look for defects away from the centre of the railhead.
5. Given the growth in numbers of rolling contact fatigue defects (such as squats and gage corner cracks), which pose a special safety risk, Railtrack should actively pursue research to gain better understanding of the way in which the defects form in order to prepare mitigation techniques.
6. For lines that carry heavier axle load freight traffic, Railtrack should consider incorporating lateral wheel load measurement into their vertical load systems.
Railhub Archive ::: 2000-11-09 ORR-001