Buried underground cables pipes utilities movement diversions and tram light rail installations

David Walmsley

Mon, 18 Feb, 22:29

to me, , , BoardBathTramGroup
I am not at all certain that running trams over excavations would be acceptable in the UK. It goes against the NRSWA safety code.
David Walmesly

David Holt

Tue, 19 Feb, 11:08

to , , BoardBathTramGroupDavidme
I wonder in what particular respect(s) it goes against the NRSWA safety code.  There are two obvious possibilities – the risks to Utilities workers from trams running above them while they work or obtain access/egress, or the risks of trams falling off temporarily-supported track, or an obvious combination of both, or the risks of the temporary supports collapsing, or of gas being ignited by tram sparking, or of some sort of clash between the two activities, or whatever else could be imagined.  Mitigations might be possible – such as doing the under-track work only when the trams aren’t running, at night for example.
I’m now going to try to put together a letter at very short notice to the Chronicle.  I’ll have to be careful not to fall foul of the constraints or to be seen to contradict other “pro tram” contributors.
David Holt

Robert Manders

Attachments19 Feb 2019, 11:47

to me

Dear Dave,

Please find attached hereto pictures of “Bump-over” points (there are other names) which can be used on either side of temporary single track in the street to allow roadworks under the other track, i.e. without stopping the tram,s running during the work.  They were taken last autumn in Wroclaw (Poland) by me.  I give you permission to use them.
Best wishes,
Robert Manders, BSc, AMA


20 Feb 2019, 10:23

to DavidDavid, , , BoardBathTramGroupme
Although too late for the publication date of the Bath Chronicle, I would like to make a few general points about the governing principles for tramway works in streets.
I believe David Holt is right to question David Walmsley’s statement that the NRSWA safety code prohibits work over excavations.  Surely the NRSWA governs the long term relationship between utilities, trams, and works in streets in general, including the all important matter of who pays for what.
I believe that the actual carrying out of work in streets, for whatever reason, comes under the auspices of the Health and Safety at Work Act (HASAWA) and its associated statutory instruments issued under its cover.  The general HASAWA principle is the elimination, or if that is not possible, the reduction of risk to all parties involved to ‘as low as reasonably practicable’ (ALARP.)  So, if you wish to construct a new, enhance, renew, or maintain an existing tramway you must do the necessary risk assessments, and then put in place the requisite precautions and mitigations.
In the UK, HASAWA etc is often seen as a prohibition of what some perceive as normal practice in Europe.  That broad brush ignores the very substantial differences in practice within Europe which pertain for numerous localised reasons.  Trams are sometimes permitted to pass through repair and renewals sites, at suitably reduced speed, and with other safety features, such as barriers and gates, in place.  Not all European renewals etc. can be so performed, and total closure of the relevant part of the tramway is sometimes necessary.  In some cities trams can be diverted to alternative routes where they exist, or, as in the UK, substitute buses are provided.  Has anyone any personal experience of performing a risk assessment for the use of Kleterwich (my spelling is probably incorrect) switches for single line operation around maintenance work in the UK? – I do not have such experience.
I hope this provides some clarity regarding the safety of tramway works in streets.  I would be pleased to read other correspondents views and insights.
Alan Wilkins

David Rumney

20 Feb 2019, 12:36
to DavidDavidmebathtramreintroductionBoardBathTramGroup

David W is quite right, but it doesn’t stop there. The relevant section of the code, issued under s.65 of NRSWA, is contained in pages 74 to 77 of the October 2013 revision of the Safety at Street Works and Road Works Code of Practice. The section starts off with the following:

“Warning: Before carrying out works in a street with a tramway, the tramway operator and highway authority must be consulted. The tramway operator will set out safety requirements to ensure safe working and to minimise the impact of works on operation of the tramway. These requirements must be followed.”

This goes along with s.93 of NRSWA on which this part of the Code is based. Subsection 93(3) says:

“An undertaker executing works to which this section applies shall comply with any reasonable requirements made by the relevant transport authority—

(a) for securing the safety of persons employed in connection with the works, or

(b) for securing that interference with traffic on the railway or tramway caused by the execution of the works is reduced so far as is practicable;

and, except where submission of a plan and section is required, he shall defer beginning the works for such further period as the relevant transport authority may reasonably request as needed for formulating their requirements under this subsection or making their traffic arrangements.”

A tramway operator needs to have its own code of practice relating to work near to the tramway so that it can readily provide the requirements for safe working close to the tramway. The first of these was developed for Manchester Metrolink in conjunction with Kit Holden and Steven Firth. This was also used as the basis for the Midland Metro and Sheffield tramways, and I imagine will also have been used with whatever modifications were necessary by all the other tramway operators.

A further consideration is s.82 of NRSWA. This says that a utility will have to compensate a relevant authority for any damage or loss resulting from work carried out by the utility. This applies regardless of whether the damage results from work carried out due to a failure of the apparatus or is straightforward repair work. Consequently the utility would be naïve to agree to leave apparatus in close proximity to a tramway unless it receives a waiver from this section (as was done in Birmingham for Severn Trent Water). Similarly the tramway operator would not sensibly agree to work being carried out in such a way as to mean that he was unable to recover costs and loss of profit if appropriate.

In my 30 years of involvement with tramway works I have frequently been embarrassed by peoples’ ideas about utility apparatus and how simply it can be dealt with by doing nothing. I’m sure that it will transpire that this was the approach adopted by TIE in Edinburgh. Please don’t get sucked into the same illusion: apparatus comes in many shapes and sizes, and lies at many depths below the road. It is vital that you know what is there long before work starts on building the tramway to understand just what will be required and when diversion work will need to be carried out. As David W has pointed out elsewhere, the utilities are extremely powerful, for good reason – they are what allow us to live in houses rather than caves –  and if you mess with them they will roll you into the ground.

David Rumney


22 Feb 2019, 11:54

to , Davidme
Further consideration is necessary.  I am grateful that David Rumney’s 30 years of experience has corrected my ignorance of the NRSWA Code of Practice.  It seems to me that it lays down principles on consultation with affected parties and statutory authorities, but does specifically prohibit or mandate any particular physical course of action.  Similarly, the HASAWA, and its associated sub-legislation, rarely prohibits or mandates any specific action, but lays down principles of consultation and risk minimisation.
The overarching principle of all UK law is one of reasonableness.  Of course, we will all have our own ideas as to what is reasonable!  With a tramway some buried services will be too close to the surface to avoid relocation.  For deeper services, what happens when maintenance access is necessary? – a promoter could run a very great risk of so many disruptions as to render the ‘service’ practically useless for any community to depend on it.  It may rapidly become a very sick joke.
There is a library of practical experience for tramway promoters, utility companies and highway authorities to draw on.  That can of course be challenged in the light of technical developments.  Changes need to be encouraged where all-round benefits are available, but do not ‘throw the baby out with the bathwater.’
I hope this helps.
Regards,  Alan.
PS.  Has anyone any experience of an attempted risk assessment in the UK for the use of the Kleterwitch (someone please correct my spelling) switches often used in Europe to facilitate single line working of tramways around maintenance sites.


David Rumney

15 Mar 2019, 16:43 (2 days ago)
to ALANDavidmeUK

I apologise for the delay in responding on the subject of the NRSWA codes and the diversion of apparatus, but I was busy having a holiday and doing other things.


Alan Wilkins’ second paragraph points the right direction for considering the issue. The law sets out what is required to be achieved, but not how. The starting point is s.84(1) of NRSWA, which requires utilities and the transport authority to identify what needs to be done with apparatus that will be affected by the tramway construction or operation, and to carry out the necessary work efficiently so as to avoid unnecessary delay to the transport authority’s work (I paraphrase but hopefully have interpreted as it is intended). You can always read it for yourself, of course.

So far, so good. The first problem comes along with the definition of the transport authority. S.91(1) defines the transport authority as “the authority, body or person having the control or management of a transport undertaking”. The tramways set up so far have arranged things in different ways, meaning in some cases that the promoter starts out as the transport authority, and this status later changes to the tramway operator. You then face the problem that the promoter and the operator may have different ideas about the criteria for the movement of apparatus: one of them adopting the risk that apparatus should remain where it is (unless it unequivocally would physically interfere with the tramway construction), while the other believes that all affected apparatus should be moved to avoid any risk of interference with tramway operations in the future. Affected is defined in s.105(4) in the following terms: “For the purposes of this Part apparatus shall be regarded as affected by works if the effect of the works is to prevent or restrict access to the apparatus (for example, by laying other apparatus above or adjacent to it)”. As a starting point, utilities have a right to require apparatus to be moved if it is affected as defined, although this has often been amended by agreement.

In deciding what action to take, in conjunction with the utility companies, my aim was always to give best value for money to my client, but this did not necessarily mean adopting the cheapest initial option. It is necessary to take into account the long term costs, though assessing these can be very difficult.

A few examples:


There was a proposal for a tram route in Glasgow from Maryhill (of Taggart fame) through the city centre to Easterhouse. In 1995 this failed to obtain the necessary powers, so never got built. Leeds Supertram, although it was granted the necessary powers, couldn’t raise the money.

Both schemes ran above or close by underground extra high voltage electricity cables. There could have been a discussion about whether to move them elsewhere, but there were good reasons to opt for removal. In Glasgow an excavator working on a different job came within a gnat’s whisker of breaching the protective cover to the cable. I was told by the electricity company concerned that because of the type of cable, breach could have resulted in the need to replace a couple of hundred metres of cable.

In regard to the Leeds cable, Yorkshire electricity gave evidence to the House of Lords committee stage of the Leeds Supertram Bill that the excavation required for repair of an extra high voltage cable would be 2.5 to 3 metres wide and around 30 metres long.

A photo of the excavation for an extra high voltage cable repair in South London, which is rather wider than the Leeds estimate, is included here.


Water can do very considerable damage to a tramway, or anything else for that matter. Around 40 years ago in Manchester a double decker bus dropped into a hole in the road. I’m not certain of the whole story as it happened before my time (David H will probably know). However my understanding is that a water main leaked over a lengthy period, gradually softening the ground beneath, which in turn led to the collapse of a sewer. The softening widened and widened until finally the weight of vehicles passing above resulted in the collapse of a very large hole (it is possible that the sewer was in fact the culverted river which ran beneath the road). Leaving water pipes beneath the tramway can be a risky business. However there is one good thing about this: not having to worry about having to dismantle the track to get at the leak: the water will do the job all by itself (see photo below).


As a rule, it should not be necessary to do much with sewers, unless they happen to be running directly beneath the track along its length. In Birmingham this was the case on Corporation Street. The first job in these circumstances is to assess the remaining life of the pipes. This is measured from 1 to 5, where 1 is top quality and 5 means don’t go within 10 metres. By agreeing to bring anything less that 2 up to standard (and to be fair there wasn’t much of that), it was agreed with Severn Trent that the pipes and manholes, with a few small alterations, could remain where they were. The quid pro quo was that STW received a waiver against the use of s.82 in the event of the need to dig up the tramway to repair a sewer. I have known a sewer repair to take 12 weeks.


In Salford there is a long-distance cast iron 36” gas main, close to but not overlapping the tram route. It was considered to be too close if a repair was needed, so that trams would have to be halted to allow the repair to be carried out. Cast iron pipes are very long lasting, and the weakness is in the old style lead jointing. The simple money-saving solution was to redo the relevant joints using modern longer lasting materials, avoiding the need to replace all the piping.

In Broad Street Birmingham there were two main gas pipes, 22” and 18” respectively. These were going to clash with the tramway alignment. Investigation of the history of the area showed that there had been something in excess of 50 industrial businesses in the area absorbing gas at the time the pipes were first laid. By negotiation, and due to the significant decrease in the quantity of gas now taken, it was agreed that the two pipes could be replaced by a single 625mm pipe.

Medium pressure pipes in Oldham and Droylsden, towns on Manchester Metrolink routes, were moved clear of the track by the gas distributer at their own expense. This was a classic example of  the benefits of maintaining amicable relationships with the utility companies (note: don’t annoy them unnecessarily).


There is a variety of communications providers. The equipment includes ancient copper cables and newer fibre optic cables. In general the copper cables are likely to be well below any possible interference with tramway construction or operation, though this isn’t always the case, while fibre cables, particularly those installed during the 1990s, can be very shallow.

Copper cables are jointed in manholes which can be very large, perhaps 6 metres in length (I expect to get a correction from David H on the subject of BT equipment!). So long as the manhole accesses are sufficiently clear of the tracks, there should be no need to do anything with them. Even where the manhole is beneath the tracks, it may be possible to alter the manhole to make it accessible even when trams are running. This was done satisfactorily in Birmingham and Oldham, saving the much higher cost of diverting cables

Fibre cables can present more of a problem. One approach used successfully is to encase the cable in the track form when it is, or can be made to be, at a suitable level.

General observations

Sheffield was taken for a ride by the sewerage authority, who managed to get an unjustifiable amount of their sewers replaced at the expense of the tram promoter. Birmingham were likewise fleeced by Midlands Electricity Board on line 1 from Wolverhampton to Snow Hill (note: make sure you know what you are doing before you start doing it).

In the end, the choice is simple to say, though not so simple to decide on:

  • can the utility agree to leave apparatus beneath the tracks? This depends on the importance of immediate repair or replacement. For example, is it providing crucial supplies to a hospital?
  • If the utility can agree to leaving the apparatus in place, can the promoter accept the consequences of closing down the tramway for an indeterminate length of time?
  • If the utility can agree to leave the apparatus in place, will the promoter be prepared to waive the effects of s.82 and absorb the risk of paying for repair of failed apparatus? If not, the utility has no obligation to leave apparatus in a position where it is affected by the tramway.

In a nutshell:

Do not be hoodwinked into believing that a tramway can be built without diverting apparatus. It will come back and bite you sooner or later, and in any case the law won’t allow a unilateral decision;

Find out what lies beneath;

Decide along with the owner of the apparatus what needs to be done with it;

Agree the cost based on NRSWA and the relevant regulations;

If the route is to go across non-highway land that contains utilities’ apparatus, the rules change. The relevant law is the Town and Country Planning Act 1990 as modified by the TWAO. This can be more difficult to deal with.


David Rumney

David Holt

Sat, 16 Mar, 11:13 (1 day ago)

to ALANmeUKDavid
David Rumney’s masterly coverage of this difficult topic prompts me to repeat my assertion that such knowledge needs to be incorporated into a training programme for future tramway engineers, ready for the upsurge in light rail installations for which we are campaigning.  There’s already a National College for High Speed Rail – surely we now need a National College for Tramways, which would probably need to be called The National College for Light Rail.  Dealing with the public utilities would be deeply embedded (sorry for the pun, couldn’t resist it) in the synopsis along with all the other multi-disciplinary matters which, uniquely, have to be dealt with both in conflict and in combination by tramway engineers “coned in the searchlights” under public scrutiny in busy city centres.  Something for UKTram to initiate perhaps?
Regarding the bus falling into a hole in Manchester 40 or so years ago, I do know that there were several collapses of Victorian sewers around that time in the city centre, and that may have been one of them, underlining my contention that the collapses were caused by overloaded tram-replacing buses.  That one was “caught in the act”.  When previously the heavy loadings were carried by trams borne on steel girder rails, there hadn’t been any such problems.  QED.  I can’t recall that actual incident, but will make enquiries a week on Thursday (March 28th) when I see other local tramway people at Tony Young’s Light Rail Transit Association talk at the Friends’ Meeting House in Manchester.
Although I do know that there are some huge underground cable chambers beneath streets in the city centre, accessed via insignificant-looking manholes tented when in use so always obscured from the public gaze, I don’t know the maximum dimensions.  Again, I’ll make enquiries next time I see the appropriate people.  There are two books – “Underground Manchester” and “Below Manchester – Going Deeper Under the City”, both by Keith Warrender, which are interesting sources though not probably for professional purposes.
Finally I’d just like to repeat that utilities enhancements should be valued as an “external benefit” of tramway installation, improving resilience against future disruptions for everyone accessing the city centre or using the connected services.  Also that the installation of extra permanent crossovers and alternative routings can enhance the tramway’s resilience against future interruptions due to utilities works or for a variety of other reasons.  Plus, if track does ever have to be dug up, it’s better that it’s simple uncomplicated tram track which doesn’t incorporate any elaborate “low level” power supply system signifying, in my view, an admission of defeat because we can’t or won’t do overhead wiring acceptably.
David Holt