- To investigate the reason(s) for the problem, and to recommend possible solutions.
- To participate in the working party and to provide ongoing comment on the appropriateness of actions proposed to allow the fleet to operate safely.
- This article by Michael Neale and Sandy Polak was first published in the Winter 1999 edition expert witness supplement of Solicitors Journal.
Experiencing the new - Single Joint Experts
Using a single joint expert from the start rather than waiting for the onset of legal proceedings may resolve a potential dispute. T A Polak and MJ Neale provide a case study.
Very few experts and members of the legal profession will yet have had experience of operating the single joint expert system. However, there have been occasions in recent years where a number of companies, with a potential dispute, have decided to use a joint expert to give them an independent and impartial opinion on the facts of their case in order to arrive at a solution.
A group of experts in a consulting engineering practice have had considerable experience of providing these joint expert services and a typical example of their experience in doing this may be of beneficial interest to readers. This is relevant to the similar activity in the new single joint expert procedure under Lord Woolf's new rules. The differences are that the lawyers are not yet involved, although they are generally on stand-by, and the procedure starts almost immediately after the particular incident occurs, rather than waiting for the onset of legal proceedings. This means that the cause of the incident has not usually been determined, let alone the possible responsibility for it. The single joint expert is therefore in a clear position to start, while all the evidence is still hot, and able to develop a professional and independent view of the case. It is therefore perhaps an idealised example of how a single joint expert will be required to work under the new rules.
Case Study: Train Coupler Failure
A good example is available from a case which started almost four years ago in which the couplings between a new class of passenger railway coaches started to fail after only a few months in service. The potential "ownership" of the problem was complicated by the railway organisation, in which the trains were owned by one company, leased to an operator with the maintenance carried out by a part of the operators organisation. Also the trains were of a recent design, and the coupling components were from separate suppliers to the company who designed and manufactured the train. A further complication was that the coupling design had been modified at a relatively late stage to meet a performance requirement of the train operating system. In the circumstances the various parties decided that the situation could be investigated more fairly and rapidly by the use of an independent consulting engineer acting effectively as a single joint expert.While this particular problem did not escalate into a court action, it had the potential to do so, as there were considerable sums of money involved in rectification actions, and differing opinions among the various parties regarding the causes and responsibilities.
Independent role benefits all parties
At the point where we became involved, the problem had only just been discovered. A coupler component between two carriages had fractured while a train was being shunted in the maintenance yard, resulting in half the train being left behind. Urgent action was required to ascertain whether other couplers were similarly affected, and whether it was safe to resume operation of the sizeable fleet of other identical trains, which had been withdrawn from service because of this failure. A working party had just been set up, including representatives from all the parties involved, to direct and manage the emergency.The brief given to the consultant was two-fold:
Ensuring Passenger Safety
The first and most important task of the working party was to ensure the safety of passengers, while at the same time keeping as many trains as possible in service to avoid major disruption. It was quickly established by examination that the fractured component had failed by fatigue, a process whereby a crack propagates progressively under repeated loadings. Computer modelling was used to predict the crack growth rate, and based on this it was determined that units with cracks below a certain size would be safe to operate for a period.An ultrasonic inspection regime was set up to detect cracks, and this was used to inspect all of the several hundred units in the fleet. Those with no cracks, or with very small cracks, were put back into service, and re-examined on an approximately weekly basis, dependent upon mileage covered. In due course, when the theoretical crack growth rate had been verified by means of this weekly examination, it was deemed safe to extend the examination interval.
At the same time, in-service measurements of stresses were carried out, and also various test rigs were set up to simulate the loads and movements experienced by the couplers in service.
Investigation Of Actual Performance In Service
Investigation of the design details and the history revealed that while this basic type of coupler had operated perfectly satisfactorily in the past on other trains, there were various differences in this case, some initiated by the manufacturers, some resulting from specifications set by the purchasers. These differences related to operational and safety requirements, the physical nature of the rail system on which these particular trains ran, maintenance procedures, and design details. All these factors appeared to have combined to cause more frequent high stresses in the component than had occurred in previous applications, and the result had been an unexpected fatigue failure.It is interesting to note that this became clear in principle fairly early in the investigation, although it was not possible initially to determine the relative sizes of the various contributing factors. The various measurements and experimental work on test rigs were largely directed at adding more detail and accuracy to the findings, as well as being used to verify various possible changes and solutions.
The recommendations included minor design changes and material changes aimed at reducing friction effects in the mechanism, which contributed to high stresses when going round curves. Also lubrication practices were improved. However, it was concluded that fundamentally the design in its current form required more substantial modifications for this particular application. The regular inspection procedures were therefore continued until a major vehicle overhaul was due, at which point a modified design of unit would be fitted.
Improved Technical Understanding
Apart from dealing with the problem, the investigation had another benefit, namely that all parties ended up with a better understanding and characterisation of the forces and duties imposed on a coupler system, which had probably never before been measured in such detail. This undoubtedly will feed back into improved purchase specifications and designs.A side-effect of bringing an independent expert in at an early stage was to promote better co-operation between the various parties. Without the presence of this informal "arbitrator", it is possible that each would have held back on certain information, fearing that it would be used against them in the anticipated dispute. This could have prolonged the investigation, certainly adding to the overall costs and disruption to the service.
Willingness To Share Information
In the conventional expert witness role, it is common that the expert only has full access to information from the side which has appointed him, particularly at the start of the investigation. In the investigation described above, having been appointed jointly by all parties, and also effectively participating in the management of the situation, information was much more forthcoming. In fact, each party appeared anxious to share as much information as possible.This type of co-operation and free flow of information makes it possible to form a balanced view based on a full understanding not only of the facts, but also of much of the underlying historical background. In technological matters, this historical background can be very important. Although many non-technical people may imagine that engineering is a precise science with every detail being researched and understood in depth, in practice this is not so. Many designs evolve from earlier designs, and these earlier designs may have been based on experience and testing, rather than on a deep understanding of every theoretical detail. This is not a criticism, and it applies to some extent in nearly all industries, from sewage to aerospace! This evolution of designs means that occasionally, new unanticipated failure modes arise, and to investigate these thoroughly requires access to the background history.
Conclusions - Avoiding Court Action
Based on our experiences in this and various other cases where we have acted as a "joint independent expert", we feel that the concept has much to recommend it, providing an atmosphere of trust and co-operation can be established. To date, experience has only been gained in this joint expert role when the opposing parties are trying to avoid court action, and are therefore trying to make the process work. If two parties are set on a court action, it may be much more difficult to create the right atmosphere.One thing is clear - the expert must not pre-judge anything, and must not voice any strong opinions prior to producing his report. Providing the expert has a genuine impartiality, it should be possible to get the necessary co-operation from both sides.
Experts Differing Views
As a final comment, we have noted that in many legal cases, the experts appointed by the two sides have substantially different expertise, a typical example being a mechanical engineer on one side, and a metallurgist on the other side. This is quite natural, as each side will have their own view on the nature of the problem, and will appoint the expert most appropriate to that view. The single joint expert will require broad knowledge covering a number of disciplines, in order to fairly consider all aspects in the dispute.
T A Polak MA CEng MIMechE
M J Neale OBE BSc(Eng) DIC FCGI WhSch FEng FIMechE FRSA FIDGTE Chairman - Neale Consulting Engineers