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Making LRT systems safe

Part Four — Past, Present, And Future

Making light rail systems safe for users and neighbours - Major C.B. ‘Kit’ Holden’s major review of the safety regime ends with his “wish-list” of safety issues that light rail promoters, developers, operators and regulators should better understand.

I am often asked what HMRI will want. The trite answer is that they don’t want anything in particular. They will say that it is up to the promoter or operator to put before them a piece of equipment, a method of operating, or a complete system for them to judge if it comes up to the required standard for public safety, taken in its widest sense. Looked at another way this could be expressed as “ Try looking at what you are showing us through our eyes”. This may sound unhelpful, but the intention is to give the widest possible choice for new developments within the spirit of RSPG (Rail Safety Principles & Guidance) and that is perhaps the key. Both the old Blue Book and the old tramways legislation appeared to give cut and dried answers with their apparently prescriptive language. Nevertheless that was not precisely the case or we would never have moved forward. There was, in practice, considerable scope within the Requirements for innovation. It was, however, equally a trap for the unwary; not infrequently an item had to be rejected despite meeting the precise letter of the Requirements because it did not fit safely into the system in which it was to operate. In other words, too narrow a view of the Requirements had been taken. The whole thrust of RSPG is to make the industry think for itself, helped by listing the factors which have to be considered. I must admit that, personally, I was a great admirer of the Blue Book and feel that we have lost something of the directness of its language. On the other hand I am equally in favour of the outcome of RSPG as it now makes plain that the responsibility for producing a safe system rests solely with the operator. It always did, as I explained in my first article, but it was not always apparent. Now that we have lost, with the partial exception of level crossings (RSPG 2E), some aspects of physical and electrical clearances, and some aspects of tramways (RSPG 2G), the setting of precise dimensions what will satisfy HMRI? We are back at the beginning of this article, in which as usual the views expressed are my own.

Another topic of misunderstanding which has become all too apparent recently is that of proof of safety; alternatively known as a safety case. Since the latter is often confused with the document required under the Railways (Safety Case) Regulations and proof seems to me to be the wrong word because it can never achieve true mathematical proof, I prefer to use the terminology of Demonstration of Safety. Now we are all, I hope, on common ground. As I said, recent examples have been far from convincing. The problem is not just one of format, important though that is in conveying clearly and succinctly the message that the system for which approval is required is safe, but of lack of understanding as to what is acceptable. It shows that insufficient forethought has been given to the question. The only guidance which I can perhaps give is that the process needs to be addressed in the way in which a lawyer might set out to convince a jury of the guilt or perhaps the innocence of a defendant or a mathematician might tackle the construction of a proof of a theorem. It requires firstly a clear statement of the object of the document, followed by an outline of how it is proposed to demonstrate that the system is safe; e.g. the various means and techniques which it was planned to use in that demonstration. Somewhere there may need to be some background information necessary for the better understanding by those who have not lived with the project for the last x years. This could be slotted in at the beginning or at this point. It also needs some indication as to whether or not those techniques were successful or were followed explicitly. Next comes the important part, the evidence. This must be in enough detail but without unnecessary padding to show why and how the submitter of the document has convinced him or herself that the system is safe. If there are conditions attached to the argument e.g. that there needs to be some operational procedure, then let them be stated here. Then and only then can a final conclusion be safely reached that the system is safe to be used. The foregoing may seem obvious to many but I believe that fewer and fewer people outside certain professions are taught how to produce the kind of document that I have been discussing or any other document for that matter. Not only is there a lack of instruction but also there seems to be a lack of insistence by senior people in an organisation that their juniors produce concise, well-directed, and objective paperwork. Badly produced submissions should always be returned to the sender with an injunction to do better.

Whilst the Guide to the Railways and Other Transport Systems (Approval of Works, Plant and Equipment) Regulations 1994 gives an indication of the process of obtaining approval to take a work into use and also provides a long list of documents or subjects which a request for approval should include, it was written from an entirely theoretical viewpoint before the Regulations themselves came into force. It was based, naturally, on the practice which had sufficed under the old legislation but perhaps it underestimated the real impact of some very subtle changes which were brought in by the new. I think that there is a very strong case for its revision in the light of four years use and it needs to address the points I have made earlier.

I was invited in writing this last article in the series to indulge in some crystal-ball gazing. However, I have decided, rather than attempt to guess what the future may hold, to consider what my wish-list might contain. High on that list must come lateral thinking both on the part of promoters of schemes but also the regulatory authorities. I have not met a scheme which did not, at some time or other, run into one or more problems. Hence my wish is that those involved should have the courage to look beyond the current conventional solution to find one which really does the job; if necessary looking back to earlier times where the problem may have been solved in a more fundamental way.

My next wish is also outside the strict boundaries of safety but could bring about a marked improvement in the way in which safety is provided. I have written earlier about the clear benefits of one partner in a Joint Venture being able to solve the problems encountered by another and instanced the interplay between the clearances required of the structural engineer and the vehicle dynamics of the rolling stock engineer. The wish therefore is a simple one; that all participants in a joint venture (JV) or consortium not only bind themselves to act as a single contractor but also do so in practice and not indulge in sub-optimisation by each pursuing their own partial interest. The financial arrangements, and I suppose the length of franchise can be included in this, must be such that proper value can be attached to the benefits of providing better quality assets at the beginning and thus reducing the maintenance costs in the long term. Hence there must be clear and obvious penalties for construction contractors who leave others to pick up a high maintenance bill; because I believe that the need for heavy maintenance can adversely affect safety if it is inadequately provided and certainly will affect the reliability of service given to the ultimate customer, the passenger. It is too early to see whether the Public/Private Partnership (PPP) method of financing which replaced the Private Finance Initiative (PFI) will be any better at encouraging JVs to consider whole life costs and Government Departments to frame the rules to make it attractive.

Space in my previous article did not allow me to expand on the need for adequate control rooms, properly equipped to discharge their function. The operator has a crucial role in defining such requirements and in planning how the service will operate to meet the promoter’s performance requirements. Hence my next wish is that the first ‘expert’ to be hired by a successful bidder is an operator rather than an engineer; that is unless he already has one in his bid team. If you can find that rara avis, an operator who is by basic qualifications an engineer, grab him or her at once. This will at least ensure that you get the control room staffing levels correct with proper allowances for time necessarily spent on crew rostering, booking traffic staff on and off duty, coping with permits to work and the odd moments to visit the washroom or canteen. One person on a shift cannot cope, I can assure you. It will also ensure that you are not tempted into reducing the numbers of vehicles and crews needed to run the service by shaving the odd seconds off a 30 minute run-time, except on those rare occasions where you are planning an automatic railway on segregated tracks and even that is risky. This philosophy of not cutting resources to the bone and not allowing sufficient contingency for emergencies must also be inculcated into all financiers, both in the private and in the public sectors.

I echo the now almost universal cry of ‘we must cut the cost of vehicles’ and of other aspects as well, but more of that later. I also agree with Harry Hondius that there are too many ‘one-offs’ but on the other hand I cannot now see us returning to the days of the PCC car and the ‘one tram fits all’ concept; our cities have each developed in their own individual ways both demographically and geographically. If we cannot afford ‘badge-engineering’, as I am certain we cannot, then how are these two opposites to be reconciled. I believe, as have some manufacturers, that the solution lies in using a ‘kit-of-parts’ design concept (the modular tram) and I wish therefore that the desire for individuality to be expressed only in the livery and a few bolt-on finials. There are two other relevant aspirations; one is that somehow the overall weight of the tram must be reduced and the other is that it is necessary to do something about the design of the bogies and in particular the traction motors. We have not yet really capitalised on the advances in electric traction technology. It is not possible here to enter into a long debate on a 100 % low-floor tram. Certainly if we are not to have obtrusive platforms in the streets the lower the floor the better, but this is yet another facet of the interplay between the civil and the mechanical engineer because there is not yet, and maybe never will be, a 100 % low-floor vehicle suitable for all applications, particularly those which involve a high proportion of high-speed, off-street running.

One effect of reducing the weight and especially the axle-load of a vehicle is that the permanent way can be made much lighter or shallower in cross-section or both and this is directly related to my next wish; do we really have to move the ‘stats’. Lewis Lesley has had one go at providing a solution to the problem with the LR55, but I am not convinced that this is the only or even the best solution. We need to consider the whole track-form, including the problem of carriage-way surfacing, and therefore we need to think about and set down precisely what everyone’s requirements are. In outline what has to be provided is a system which will allow the track to be ‘undermined’ to give access to the buried services. If the track remained able to support the passage of a tram, albeit at low speed, and a safe system of work instituted, then it would be unnecessary to stop the tramway operating during emergency or other works in the highway. A conceptual idea might be to liken the support to each rail to a viaduct where a continuous span is supported on piers which, in this case, would be short, bored piles joined by a cross-beam. An alternative for avoiding highway works which would be more easily used were the weights of tram and track to be lower would be to use a form of applique track as John Parry did when demonstrating his Parry Peoplemover at various exhibitions. This ‘tin-plate’ temporary track would be laid directly on the road surface along a diversionary alignment and afterwards removed.

This whole series of articles was supposed to examine how, why and what the safety regime for tramways in the UK has become what it is. It has, of necessity, been only possible to give a flavour of some very complex issues but I hope that in doing so I have been able to cast some light on why we are at the point at which we are now. However I thought that by way of a summary I might merely set out a few of the aphorisms which have been associated with or been coined by HMRI during the course of its work as I think that they serve as well as anything to illustrate a little of the philosophy behind their judgements. They are not in any particular order and I have made no attempt to join them together. Here they are.

And finally, in the words of a distinguished lawyer well known in the tramway world, “Since when has lack of powers ever stopped the Inspectorate from doing what they consider to be right and in the public interest.”. Long may this state of affairs continue.

Oops! A couple of gremlins crept into earlier parts in this series: in Part Two ‘prescribe’ managed to lose an ‘e’ and gain an ‘o’, becoming ‘proscribe’ and thereby practically reversing the intended meaning. This has now been corrected.

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