See also: https://bathtrams.uk/discussion-on-buried-utilities-movement-diversions-and-tram-installations/ a later discussion.
The above images indicates how rapidly tram tracks can be diverted whilst services are maintained or moved.
Here is a video of temporary tram tracks in operation: https://www.youtube.com/watch?v=33FAA4pzRkA
“Kletterweiche” are a form of temporary tracks laid on the surface of the road to effect a diversion if large excavations for utility work is required. See images below from Wroclaw Poland 2015:
WORD VERSION OF ABOVE LETTER
Response to Peter Fox, Letter to the Bath Chronicle of 3 May 2018
Mr Fox, in his letter to the Chronicle of 3 May, is quite correct in drawing attention to the cost of diverting utilities’ apparatus as a heavy burden on tramway proposals. But this is not necessarily the sole reason why proposals to build tramways fail.
There have been two modern attempts to build a tramway serving Bristol. I was invited by the promoter of the first scheme, the Advanced Transport for Avon which obtained statutory powers in an Act of 1989, to use my experience in managing diversions, shortly before the scheme was abandoned. As a result I can be fairly sure that the cost of diversions was not the main factor in the decision to drop it, as it was unknown at that stage. It seems that the later proposal for the Bristol Supertram was abandoned in 2004 so that the money set aside for its development could be used to cover a projected council tax increase, which again implies that the cost of diversions was not a major factor.
In any project funded publicly, at least in part, the essential requirement is that the benefit deriving from it exceeds the cost of providing it by an acceptable margin. This means assigning a cost to all elements of the project, of which diversion of apparatus is only one. If the benefit to cost ratio can be demonstrated to be satisfactory, the individual cost of the various elements is of no real concern.
The Edinburgh Tramway is the subject of a Public Inquiry, which is now coming to an end. It is important to wait for the final report to be released, rather than simply assuming the cost and duration of the diversionary works could not have been reduced by better management.
What happens to apparatus below or close to a tramway is determined by the New Roads and Street Works Act 1991. The Act merely requires the tramway promoter and the owner of apparatus to “identify any measures needing to be taken” to allow the tramway construction to be undertaken. There is no obligation on the utility company to move the apparatus, nor will they necessarily do so. As an example, sewers are normally located well below the level at which they could be affected by the tramway operations. If the sewer is in a satisfactory condition and can be accessed via a conveniently placed manhole, it is normal to leave it beneath the tracks. Similarly much of BT’s network is several meters deep and under favourable circumstances will not be diverted.
Having managed or advised on diversion of apparatus for several UK tramways, including Manchester Metrolink, Midland Metro, Strathclyde, Leeds Supertram, Sheffield Supertram extensions and Nottingham Express, I have great confidence in the possibility of keeping diversion costs at a manageable level. Over the last 30 years of tramway development, many cost saving measures have been agreed between promoters and utility companies. But this requires close co-operation between both parties from a very early stage in the development of the tramway, and failure to ensure this happens is the most likely way to end up in the situation met by Edinburgh and some of the other tramways.
( David Rumney is a chartered engineer, and a (retired) member of the Institution of Civil Engineers, the Institution of Highways and Transportation and the Institute of Arbitrators. Involved in the planning of many UK successful tram systems such as the Manchester Metro-link, Birmingham, ( but not Edinburgh) and varying levels of involvement in Croydon, Liverpool and Nottingham, Leeds Supertram ( not built – Alistair Darling cancelled the scheme along with that of Liverpool.) . Expert in the issue of underground utilities diversions ( full expertise listed below in Advisory Group))
Above – track system in Den Haag, simply concrete pads on sand which permits easy access to buried services.
LETTER FROM BOB CHARD
My expertise in this is that as part of the design and costing work for the proposed Greenwich Waterfront Transit (GWT)project (tram technology option) I did a desk top cost evaluation of the costs of utilities relocations in Woolwich. It was agreed that for that project utilities costs would be significant and that was a reason why the alternative option of an electronically guided busway was eventually preferred; but subsequently also abandoned for different reasons. There are some important facts about utilities costs which are not mentioned in David Rumney’s letter which are :-
- There are about 20 different types of “utilities”; some types are very costly to relocate and some have virtually no cost to relocate.
- Not every type of utility is found in every street. We do not know yet what we have in Bath.
- In virtually all new highways constructed since about 1960 no utilities are located under the carriageway at shallow depth; and therefore no relocations are necessary or required.
- Therefore because of 1-3 above the % of a tram project’s cost which goes to utilities relocations is very variable on a range from 0% to more than 25%
- Therefore in a city such as Milton Keynes which is entirely built since 1960 a tram system would have no utilities relocation costs at all.
- Therefore in a city such as Edinburgh, which has an abundance of every type of ancient and dilapidated utilities it is inevitable that utilities reconstruction costs will be not just above average but exceptionally high.
- Therefore the part of the proposed GWT tram route in old Woolwich had exceptionally high utilities relocation cost estimates and the part in newer Thamesmead had almost zero relocation costs.
- Legislation pursuant to the New Roads and Street works Act defines how the costs of any agreed, or not agreed, utilities relocation costs will be negotiated and “shared” between the tram promoter and the highway owners. Parliament can and has in the past, changed the rules of engagement. This applies whether public money is involved or not.
- Obviously Edinburgh could have negotiated poorly, underestimated the risks and signed up to a very poor deal. Some commentators say that they did just that, and set a new UK and world record for incompetence and high utilities relocation costs.
- MOST IMPORTANT; technology improves all the time and allows tram projects all over the world to do everything better and at lower cost. Tram track technology is no exception. All the above historic costs are now irrelevant because in future about 90% of what used to be “necessary” relocations are no longer “necessary” if LR55 track is used; and it can be used almost everywhere, including in Bath.
- Unfortunately even as the Preston Tram line 1 is being built with LR55 track for ULR tramcars, to eliminate all utilities relocation costs from that tram system, the WS Atkins report to Bath Council has assumed that Bath will only have old style slab track with costs similar to Edinburgh. That assumption is not inevitable and is therefore wrong and unhelpful.
Bob Chard, Member of the ULR Group of UK Tram
LETTER FROM PROFESSOR LEWIS LESLEY DEVELOPER OF PRESTON TRAMS
Such utility works have to be done in reasonable co-operation with other
utilities, including tramways. The HMRI has provided a “possession
arrangement” for utility works under active tram tracks. This includes
diverting road traffic away.
Obviously for catastrophic utility failures, eg. gas main/water main
bursting, trams would have to stop, for about a week. Such failures are
however 1 in 40 year events. A economic exercise was undertaken for a
proposed tramway to Liverpool Airport. This showed that if the cost of
utility diversion was more than £160k per km, then it is better to leave
plant in place and lose a week’s tram revenue every 40 years.
Trampower includes a conservative figure of 9% of track costs for utility
accommodation works, with LR55 tracks, since as Bob Chard has pointed out,
there are no utilities in the top 300mm of a road, except for magnetic loop
detectors for traffic signals, which are being phased out in favour of radar
detection. And from many discussions with Utility Companies, not having to
move plant is their dream, provided access is available between rails. LR55
rails self support over 1m wide trenches.
Prof. Lewis Lesley BSc, AKC, PhD, CEng, MICE, FRSA, FCIT, MTPS
LETTER FROM DAVID RUMNEY TO BATH TRAMS MAIL GROUPS 20TH NOVEMBER 2018
I feel it is time to introduce some reality to the situation, as someone who has had practical experience in tramway planning, design and construction. There is a lot of waffle spoken, but the biggest concern is the attitude regarding utilities. You should understand that no-one is in a position to state that utilities do not need to be moved because a particular type of track construction is to be used, unless they are either the transport authority or the utility concerned. To do otherwise is a sure route to the same disaster as befell Edinburgh, as I shall explain.
I’ve been unable to discover the depth of the tracks of those claiming that their systems do not require diversions, but my guess is slightly in excess of 300mm. The original track depth for Manchester Metrolink was 450mm, not very different. What is being overlooked is that the total excavation depth for the track was around 900mm, to accommodate all the cables that are required for the running of a tramway, and this is not related to the track depth.
It appears to be assumed that the utilities place their apparatus at a constant and predictable depth. This overlooks the reality, which is that they are all over the place. As they have been added to over more than a century, they get moved around, lowered, raised and adjusted in various ways to accommodate more and more apparatus, while defunct apparatus is rarely if ever removed. In the 80s when telephone cable was being installed by the likes of NYNEX, it was mainly installed at a depth of around 250mm regardless of whether this was in the pavement or the carriageway. It was not unknown for pavement stones to stick out above their surroundings because the cable was so shallow.
There is an assumption that apparatus, if it fails beneath the tramway once it is in operation, can be easily replaced overnight without affecting the running of the tramway during the daytime. This is very far from the truth: some complex diversions can take months to repair. Repair of an underground extra high voltage electricity cable can take many weeks: these are present in both Leeds and Glasgow and would have been affected if their tramways had been built. Failed sewers or a failed large gas mains can likewise take a considerable time to repair or replace. It is essential that the promoter of a tramway knows what is underground before even making a final choice of route for the tramway.
The relevant law, which trumps ill-informed opinion any time, is the New Roads and Street Works Act 1991, specifically sections 84 and 85. In the normal way of things, if a utility wishes to install new apparatus in the street, it will probably have to persuade another utility to make way, and will have to pay the costs incurred by the obliging utility. If no room can be found, the apparatus can’t be accommodated. The tram promoter, although a statutory authority like all the utilities, is given special privileges by section 84 of the Act which ensures that the utilities must move their apparatus to accommodate the tramway. The transport authority and the undertaker (i.e. utility) are required (i.e. shall take such steps) “to identify any measures needing to be taken” to allow the tramway to be constructed without unnecessary delay. The principle underlying the identification of necessary measures is that the apparatus concerned will or may be affected by the tramway construction or operation, and apparatus is regarded as being affected if “the effect of the works is to prevent or restrict access to the apparatus”.
It is impossible to exaggerate the importance of starting discussions with the utility companies at an early stage in the process of planning the route of the tramway. In any case, the utilities will have to be involved once preparations are made for gaining statutory powers to build the tramway.
The Manchester tramway was the first of the second generation tramways to come into operation. More than thirty years ago we agreed that not only did we not know all the answers to tramway construction, but also that we did not know many of the questions. There are now many more people who have been involved in tramway schemes, who have asked the questions and found the answers. It is no longer necessary to make the same mistakes as were made in Edinburgh by effectively ignoring the issue of utilities until it was too late to avoid enormous additional costs.