Hope Valley Capacity Scheme updates

[Taunton]

In which connection I'll wonder again how a single lead junction saves cost compared with a double junction (crossover not diamond) when both have four point ends - never seen a satisfcatory justification for this.

Indeed, and the elimination of head on collisions that have happened at such layouts. I can think of at least half a dozen straight off, mostly concentrated in their earlier years. I wonder if these are still factored into the Risk Assessment of such layouts. The only justification for doing single lead with still four point ends is that extra space is needed beyond a conventional double junction for the merging line to run alongside for a brief distance while the diverging line crosses over, and then turns off in parallel. If up on an embankment etc this extra space may not be available.

I also wonder what is SO difficult nowadays about the civils maintaining either a conventional, or switch diamond, crossing. Is it a case of one department sticking their problems/expense onto another department.

 

[MarkyT]

Indeed, and the elimination of head on collisions that have happened at such layouts. I can think of at least half a dozen straight off, mostly concentrated in their earlier years. I wonder if these are still factored into the Risk Assessment of such layouts. The only justification for doing single lead with still four point ends is that extra space is needed beyond a conventional double junction for the merging line to run alongside for a brief distance while the diverging line crosses over, and then turns off in parallel. If up on an embankment etc this extra space may not be available.

I also wonder what is SO difficult nowadays about the civils maintaining either a conventional, or switch diamond, crossing. Is it a case of one department sticking their problems/expense onto another department.

At some junctions, a single lead arrangement can allow longer turnouts and thus higher speed. There may not be enough alignment width to make a parallel double junction with individual turnouts as these are always longer than a junction with diamonds of one sort or another. Switched diamonds are not generally liked. They're difficult to keep in adjustment and are considered unreliable. Fixed diamonds in a classic double junction configuration are the most economical solution for point ends, with only two machines required, and have become more popular again in modern layouts. They have a minimum crossing angle however that in many junctions would limit speed unacceptably. Sometimes it's worth sacrificing turnout speed for a double junction of some type. Sometimes a single lead remains the best compromise.

 

[Taunton]

The most extreme parallel double leads have to be Foxhall Junction east of Didcot, where the crossovers now extend over the best part of a mile towards Paddington, for trains to/from the Main lines to get right across to the Didcot Avoiding line. They actually seem to extend considerably the time in which crossing trains block all other movements. I know it's meant to facilitate high speeds for diverging trains, but in practice down trains to Oxford invariably (at least when I am on them) get a severe signal check from conflicting services.

I seem to recall the old GWR, no less, had originally installed switch diamonds here, which lasted for a long time.

 

[MadMac]

I'll wonder again how a single lead junction saves cost compared with a double junction (crossover not diamond) when both have four point ends - never seen a satisfactory justification for this.

One little-publicised fact that emerged in the wake of the ill-fated Newton remodelling was that it basically saved about 50’ of plain track.

 

[mwmbwls]

Very sensitive subject in Sheffield!

Hope Valley Capacity Improvement Scheme was originally designed to provide 4 fast passenger paths an hour, plus the slow and freight paths. That included 3 loops, at Chinley as well as Grindleford and Dore. Examination of that resulted in massive opposition at Grindleford and Bamford being substituted. My understanding is that capacity constraints at Stockport further impacted on the case for all those paths and the Chinley loop was considered unnecessary. A shame because it was on flat railway land and probably the easiest to construct.

A feasibility study was prepared to consider reinstating all 4 platforms at Dore to make it a junction, as it was until the 1960s. That might have offered a new range of options, but building platforms long enough for MML and XC trains would have been problematic on several grounds, apart from delays to fast services - and cost. Pushing HS2 down the Sheaf Valley must make that a total non-starter today.

I referred earlier to the tight Dore curve. When the Hope Valley line was being planned an early consideration was to build what we'd call today an interchange station on what is known locally as the railway triangle. A quick look at the maps and knowledge of platforms on curves and gradients will show why that idea didn't fly! Those who don't understand these matters still try to suggest it today.

For those unfamiliar with the layout at Dore - I annex the Network Rail Press Release Diagram

Hope Valley Capacity Works - Bamford and Dore by Mwmbwls, on Flickr

 

[Killingworth]

For those unfamiliar with the layout at Dore - I annex the Network Rail Press Release Diagram

Hope Valley Capacity Works - Bamford and Dore by Mwmbwls, on Flickr

The Dore & Totley Station underbridge carrying the Hope Valley tracks over the River Sheaf was to be replaced but has been assessed as sound. That will save at least a £1m.

 

[Taunton]

One little-publicised fact that emerged in the wake of the ill-fated Newton remodelling was that it basically saved about 50’ of plain track.

I'd have liked to have seen the Risk Assessment for the scheme.

 

[edwin_m]

I'd have liked to have seen the Risk Assessment for the scheme.

I don't think there would have been one in the 1980s. Safety cases for rolling stock didn't come in until the 90s and I think infrastructure was later, probably early 2000s for layout risk assessments.

 

[Killingworth]

At the public inquiry stage I managed to snap some of the plans. At the time all the boxes of documents were online and I assumed they'd remain available, but they didn't!

Here are plans for Dore station and the Dore loop. You'll see that part of the current difficulty for day to day operations and this construction scheme is that the area of the Bamford work is currently in LNW, with the Dore loop being half in LNE together with Dore station.

 

[Tomnick]

The 90 degree uphill turn off the Hope Valley onto the MML round the Dore curve through Dore Tunnel is one of the less well appreciated factors in the scheme. That used to be double track and is quite a tight turn. There used to be much squealing of wheels as some wagons clearly found it so. The new loop leading to it at Dore may not be long enough for the longest trains now being planned. It was originally thought possible to make it longer by demolishing some flats at West View. That would have added a lot more expense, aroused even more local opposition than running the loop right up to their car park, and was dropped even before the first round of public consultation. The Bamford loop is to be longer.

There is no easy way to avoid potential conflicts when a heavy load of cement or limestone is dragged round the curve to head south. That causes delays to both north and southbound MML traffic unless everything presents itself exactly as planned. A grade separated junction would be ideal, but incredibly expensive to construct even if it could be engineered! Think on.

...

Signalling is another factor. Although the scheme includes transfer of control from Earles to York from Manchester, thereby potentially improving control over the Dore junctions, there will be no change in the blocks. Line speeds will not be improved and as I currently understand it 185s will be unable to use their full capabilities, 158s currently being able to run faster in the Hope Valley due to lighter weight.

Dore Curve, or the traffic using it at least, is a big problem and loops at Bamford alone won't sort it. The problem is that a loaded freight train from the Hope Valley has to fit into a suitable margin on the busy (and fast) line south towards Chesterfield, but also needs gaps in both traffic from Chesterfield and towards the Hope Valley to do so, and it all has to line up at once unless it's short enough to stand on the curve (and it can't even do that without a gap in trains from Chesterfield because the overlap extends over the junction). It's almost inevitable that something's going to get knocked by it, e.g. the following train heading south because it's had to be run with insufficient margin to get it out of the way of the following train off the Hope Valley. The ability to put them away at Bamford, and bringing it all under York's "control" won't help much, because things can and do change a lot in the time that it takes to get from a standing start at Bamford to passing Dore. Even if you can identify a suitable margin to run it, a passenger train delayed by just four or five minutes at Sheffield could upset the whole plan. I don't have much confidence in their ability to make such tight and distant decisions with their almost complete reliance on ARS, in any case!

The only way to really deal with it is to provide enough room to stand the longest train inside clear on the curve, so that it can be kept out of the way until a suitable margin is available to run it. I'm not sure whether the current proposal provides that, although it does at least appear to extend the curve considerably.

Going westwards a fast passenger service will still be unable to pass a stopper between the Heeley loop and after Chinley. Whether the Bamford loop will be used to allow a fast to overtake a stopper is a subject of interest. Who makes that decision and how do the penalties get passed around when the already late stopper has to take another 5 minute hit?

As always, when one bottleneck is eased the pressure starts building further along the line. Like 60mph restrictions on 3 long tunnels.

Network Rail makes the decision, either the Signalman directly or the Train Running Controller, with the objective of minimising the overall delay. As with the example of Glazebrook, which is where the CLC stopper invariably gets recessed when the Norwich - Liverpool service is late because it's been hammered over the Hope Valley, putting the stopper inside for a few minutes would usually be preferable to keeping it out and delaying the following fast by many more minutes.

None of the three tunnels have a 60mph restriction?

Shorter signal blocks would help massively as some of them are immensely huge. Not only that, but the heavily-talked about of the splitting of Norwich-Liverpool would need to be a priority to alleviate delay. There's far too many pinch points to incumbere the Hope Valley at the moment.

As Edwin_m suggests, splitting the Norwich - Liverpool service won't help much. It has some recovery time at Nottingham (and approaching Sheffield) to cope with minor delays without destroying the 'connection' for through passengers, and it's common for it to be 'restarted' right-time at Nottingham if the inward from Norwich is significantly delayed.

The longest block sections over there are Totley Tunnel East - Grindleford and Edale - Chinley, and in neither case is the section very much longer than the tunnel in the middle of it (so you can't shorten the section by much without introducing stop signals in the tunnel itself). You'd be able to squeeze a couple of minutes, perhaps, with shorter sections but that won't help much when there's such a big differential between the average speed of the stopping passengers and freights, and the average speed of the fasts.

 

[Killingworth]

It isn't going to happen, but I understand electrification of the Hope Valley line has been considered and the new footbridge at Hathersage West will be designed to that standard, as will the one at Dore station. Last year I spoke to a fellow passenger who said he'd wasted a year of his time planning such a scheme. His comments might be of interest to those looking at North Pennine electrification.

To electrify Hope Valley would need some very lengthy blockades with no easy alternative routes between Sheffield and Manchester. One blockade of about a year might get most of it done but impossible without effectively having to close the Hope Valley cement works, and restrict the quarries at Buxton to having to use westbound routes only. Blockades to electrify Cowburn and Totley tunnels separately would double the time passenger services would be blocked but would allow freight from Hope to escape.

However, bi-modes could be operated if the MML were electrified from Sheffield to Dore for HS2 and then again in the Manchester and north-west area, with easier infill sections over the coming decades.

No, I can't see it happening in my lifetime, and an entirely new line isn't likely any time soon either.

 

[_toommm_]

It isn't going to happen, but I understand electrification of the Hope Valley line has been considered and the new footbridge at Hathersage West will be designed to that standard, as will the one at Dore station. Last year I spoke to a fellow passenger who said he'd wasted a year of his time planning such a scheme. His comments might be of interest to those looking at North Pennine electrification.

To electrify Hope Valley would need some very lengthy blockades with no easy alternative routes,between Sheffield and Manchester. One blockade of about a year might get most of it done but impossible without effectively having to close the Hope Valley cement works, and restrict the quarries at Buxton to having to use westbound routes only. Blockades to electrify Cowburn and Totley tunnels separately would double the time passenger services would be blocked but would allow freight from Hope to escape.

However, bi-modes could be operated if the MML were electrified from Sheffield to Dore for HS2 and then again in the Manchester and north-west area, with easier infill sections over the coming decades.

No, I can't see it happening in my lifetime, and an entirely new line isn't likely any time soon either.

The only semi-viable alternative to Manchester would be via Huddersfield, but with how congested the north throat of Sheffield is, along with persistent lateness of services along the Huddersfield to Stalybridge corridor, it may not exactly work sending 2 extra services an hour each way through.

Just out of curiosity, what diversion routes do EM sign if the Hope Valley is closed? Can't imagine them having via Huddersfield

 

[Killingworth]

Just out of curiosity, what diversion routes do EM sign if the Hope Valley is closed? Can't imagine them having via Huddersfield

Usual practice seems to involve a bus - or when weather's bad, nothing!

 

[yorksrob]

Time was when electrification would be completed using "wrong line" working.

 

[furnessvale]

Dore Curve, or the traffic using it at least, is a big problem and loops at Bamford alone won't sort it. The problem is that a loaded freight train from the Hope Valley has to fit into a suitable margin on the busy (and fast) line south towards Chesterfield, but also needs gaps in both traffic from Chesterfield and towards the Hope Valley to do so, and it all has to line up at once unless it's short enough to stand on the curve (and it can't even do that without a gap in trains from Chesterfield because the overlap extends over the junction). It's almost inevitable that something's going to get knocked by it, e.g. the following train heading south because it's had to be run with insufficient margin to get it out of the way of the following train off the Hope Valley. The ability to put them away at Bamford, and bringing it all under York's "control" won't help much, because things can and do change a lot in the time that it takes to get from a standing start at Bamford to passing Dore. Even if you can identify a suitable margin to run it, a passenger train delayed by just four or five minutes at Sheffield could upset the whole plan. I don't have much confidence in their ability to make such tight and distant decisions with their almost complete reliance on ARS, in any case!

The only way to really deal with it is to provide enough room to stand the longest train inside clear on the curve, so that it can be kept out of the way until a suitable margin is available to run it. I'm not sure whether the current proposal provides that, although it does at least appear to extend the curve considerably.

Sounds like a case well made for reopening Great Rocks to Matlock for freight!

 

[yorksrob]

Sounds like a case well made for reopening Great Rocks to Matlock for freight!

Indeed. Infact why not reopen it for passengers as well.

 

[Killingworth]

Sounds like a case well made for reopening Great Rocks to Matlock for freight!

To bring that up to modern standards through the tunnels and over viaducts, plus restoring from Matlock to Ambergate to permit mixed passenger and freight workings, would take a decade to plan if recent precedents are anything to go by. The public outcry in the Peak District and inevitable public inquiry might add another. It was bad enough for this limited scheme. Plus finding cash in CPs 7-12 and later! Maybe one day.

 

[Tomnick]

Time was when electrification would be completed using "wrong line" working.

Time was when they'd probably end up killing a few workers too!

I suspect the size of the equipment used nowadays (to speed the job up?) would preclude single line working for much of the work anyway.

Sounds like a case well made for reopening Great Rocks to Matlock for freight!

Quite possibly! The ability to stand a longer train on Dore Curve is slightly more achievable in the medium term though

 

[DanTrain]

It isn't going to happen, but I understand electrification of the Hope Valley line has been considered and the new footbridge at Hathersage West will be designed to that standard, as will the one at Dore station. Last year I spoke to a fellow passenger who said he'd wasted a year of his time planning such a scheme. His comments might be of interest to those looking at North Pennine electrification.

To electrify Hope Valley would need some very lengthy blockades with no easy alternative routes,between Sheffield and Manchester. One blockade of about a year might get most of it done but impossible without effectively having to close the Hope Valley cement works, and restrict the quarries at Buxton to having to use westbound routes only. Blockades to electrify Cowburn and Totley tunnels separately would double the time passenger services would be blocked but would allow freight from Hope to escape.

However, bi-modes could be operated if the MML were electrified from Sheffield to Dore for HS2 and then again in the Manchester and north-west area, with easier infill sections over the coming decades.

No, I can't see it happening in my lifetime, and an entirely new line isn't likely any time soon either.

Hahaha we can dream . I personly think it's far more likely that a brand new road-rail tunnel will be built under the Pennines than this happenening, and that road-rail tunnel has been a pipe dream almost since the Woodhead closed! It is however probably the only true solution to the problem...just a small hitch on the price tag .

 

[yorksrob]

Time was when they'd probably end up killing a few workers too!

I suspect the size of the equipment used nowadays (to speed the job up?) would preclude single line working for much of the work anyway.

Quite possibly! The ability to stand a longer train on Dore Curve is slightly more achievable in the medium term though

I don't recall reading about large numbers of fatalities during the ECML electrification scheme !

Also, if the have to close these lines for years on end, the modern methods can't have speeded up the process that much.

 

[mwmbwls]

To electrify Hope Valley would need some very lengthy blockades with no easy alternative routes,between Sheffield and Manchester. One blockade of about a year might get most of it done but impossible without effectively having to close the Hope Valley cement works, and restrict the quarries at Buxton to having to use westbound routes only. Blockades to electrify Cowburn and Totley tunnels separately would double the time passenger services would be blocked but would allow freight from Hope to escape.

However, bi-modes could be operated if the MML were electrified from Sheffield to Dore for HS2 and then again in the Manchester and north-west area, with easier infill sections over the coming decades.

Blockades to electrify Cowburn and Totley Tunnels would indeed be time consuming. Both tunnels are wet - in particular Totley tunnel, whose working headings collapsed as a result of broaching a spring during construction. The tunnel has required a disproportionate of maintenance ever since. During my time as a resident of Grindleford, there was a PW train stabled next to the Grindleford signal box used to provide a mobile platform for masons and bricklayers involving in a perpetual repointing exercise. In 2012,Network Rail contractor, J W Murphy, pioneered techniques in Totley Tunnel to replace labour intensive manual pointing by injecting quick drying grout that enabled faster and more effective repairs. Although the technique works, it is still a symptomatic rather than a causal solution because of the inherent wetness of the tunnel.

The use of catenary bar rather that wire in tunnels has also become common. See - https://www.railforums.co.uk/thread...ad-conductor-bars-instead-of-catenary.166890/ - I am not aware of how water/ice tolerant such systems are. But I suspect that similar concerns are driving, at least in part, the DfT decision not to electrify Standedge. The solution would appear to be discontinuous electrification - that is not electrifying Cowburn and Dore and Totley but electrifying the open stretches, (harvesting, for example, the regenerated power on the downhill runs from Cowburn through Edale) and using bi-mode locomotives under the MML wires.

 

[Tomnick]

I don't recall reading about large numbers of fatalities during the ECML electrification scheme !

Also, if the have to close these lines for years on end, the modern methods can't have speeded up the process that much.

Even a small number would be too many!

I shouldn’t think you would have to close the lines for years on end. With a full block, you’d be able to get it done pretty quickly, albeit in two halves to maintain access to Earles throughout. I doubt that would ever be politically acceptable though.

 

[DanTrain]

Even a small number would be too many!

I shouldn’t think you would have to close the lines for years on end. With a full block, you’d be able to get it done pretty quickly, albeit in two halves to maintain access to Earles throughout. I doubt that would ever be politically acceptable though.

Also, unless done over Christmas/Easter, what would you do with the people who rely on the line to get to work? It's not very easy to divert and buses would take forever.

 

[yorksrob]

Even a small number would be too many!

I shouldn’t think you would have to close the lines for years on end. With a full block, you’d be able to get it done pretty quickly, albeit in two halves to maintain access to Earles throughout. I doubt that would ever be politically acceptable though.

There needn't be any if you can erect some sort of portable physical barrier between the working area and the running line, which must surely be possible.

 

[Chester1]

Blockades to electrify Cowburn and Totley Tunnels would indeed be time consuming. Both tunnels are wet - in particular Totley tunnel, whose working headings collapsed as a result of broaching a spring during construction. The tunnel has required a disproportionate of maintenance ever since. During my time as a resident of Grindleford, there was a PW train stabled next to the Grindleford signal box used to provide a mobile platform for masons and bricklayers involving in a perpetual repointing exercise. In 2012,Network Rail contractor, J W Murphy, pioneered techniques in Totley Tunnel to replace labour intensive manual pointing by injecting quick drying grout that enabled faster and more effective repairs. Although the technique works, it is still a symptomatic rather than a causal solution because of the inherent wetness of the tunnel.

The use of catenary bar rather that wire in tunnels has also become common. See - https://www.railforums.co.uk/thread...ad-conductor-bars-instead-of-catenary.166890/ - I am not aware of how water/ice tolerant such systems are. But I suspect that similar concerns are driving, at least in part, the DfT decision not to electrify Standedge. The solution would appear to be discontinuous electrification - that is not electrifying Cowburn and Dore and Totley but electrifying the open stretches, (harvesting, for example, the regenerated power on the downhill runs from Cowburn through Edale) and using bi-mode locomotives under the MML wires.

If its just the two tunnels being left then small batteries would be much better than bi modes. Its surprising that they are not being fitted to most new long distance EMUs to cope with power failures. If only a 10-15 mile range is needed then the extra weight would be negligible.

I expect to see Hope Valley wired within my lifetime although I am younger than many members. I think smaller schemes like Wigan-Lostock will be the successors to GW, MML and TP electrification (once it actually starts and finishes). Give it 10-15 years and most DfT staff and politicians will have moved on. I am confident that the green agenda combined with being shamed by continuing Scottish electrification will keep electrification going in England and Wales on a smaller scale.

The priority for Hope Valley investment must be capacity, its woefully short, both in terms of train length and frequency.

 

[Killingworth]

The ability to stand a longer train on Dore Curve is slightly more achievable in the medium term though

To aid understanding, at the time the Hope Valley Capacity Improvement Scheme was being planned it was working on an assumption of heavily laden 640m trains filtering out north through Sheffield and 520m trains going south round Dore South curve. Clearly taking a heavily laden train round the tight (I'd say about 80 degrees?) curve at Dore means crossing the westbound Sheffield-Manchester tracks, and then the northbound Derby - Sheffield MML. It's on an uphill grade so additional length would bring greater weight and a harder train to propel across the tracks.

At present even a typical 417m train cannot avoid fouling at least one track if standing on the bi-directional Dore curve (it used to be double track until 1985) where there's 322m between the controlling signals 53 and 48 at either end. When trains sometimes get trapped there they can block traffic in both directions, including empty freights coming up the Sheaf Valley from Sheffield! I'm sure delayed passengers and train crew must regularly curse when this happens! In earlier days (possibly shorter) trains did stand there regularly, often for quite long periods at night, the locomotive noise being audible for quite some distance in still air!

The designed length of the Bamford loop is 1089m to include 117m crossover, 640m train, 10m stopping tolerance, 25m signal stand back, 180m overlap and another 117m crossover. I've not kept a record of the precise length at Dore but it seems likely the lead in and out distances will be similar.

 

[Killingworth]

If its just the two tunnels being left then small batteries would be much better than bi modes. Its surprising that they are not being fitted to most new long distance EMUs to cope with power failures. If only a 10-15 mile range is needed then the extra weight would be negligible.

I expect to see Hope Valley wired within my lifetime although I am younger than many members. I think smaller schemes like Wigan-Lostock will be the successors to GW, MML and TP electrification (once it actually starts and finishes). Give it 10-15 years and most DfT staff and politicians will have moved on. I am confident that the green agenda combined with being shamed by continuing Scottish electrification will keep electrification going in England and Wales on a smaller scale.

The priority for Hope Valley investment must be capacity, its woefully short, both in terms of train length and frequency.

I'd agree. Battery back up to span relatively short gaps in the wiring must be feasible now, after all the 3 tunnels between Sheffield and Manchester (Totley, Cowburn and Disley) don't add up to 10 miles.

However, the flaw in that at present is that the route miles between, say, Manchester Airport and Cleethorpes are unlikely to be wired up for a long time, and from Liverpool to Norwich probably even longer. That wouldn't prevent a 769 type hybrid of some sort becoming viable on the Sheffield-Manchester section.

In the meantime more 6 coach TPE 185 trains are creeping in, East Midlands are managing to run full 4 car 158s more reliably, and Northern are increasingly becoming 150 operated. (Pacer chasers aren't doing so well!) As capacity improves the journeys will become more comfortable and more will use them.

Currently with 3 operators price competition is favourable for passengers who can be flexible about time - and anyone wanting to go further afield will probably get even better value with split ticketing. (Dore to Manchester Airport is a shorter journey but a lot dearer than Sheffield to the Airport. Don't book straight through - but that's for another thread.)

 

[edwin_m]

The HOPS train ordered for the GW electrification included moveable barriers which were intended to allow work to be done with the adjacent line open. Clearly this train didn't deliver the planned efficiency but I don't think that's a reason to abandon any hope of electrification with adjacent line open in the future.

However if it's a question of lowering the track in the tunnels that could be another matter - I can't imagine one track being dug out below formation level while trains are running on one a few feet away.

Surely the ultimate wet tunnel must be the Severn? If the rigid bar system works well there then won't it work almost anywhere?

 

[Killingworth]

Surely the ultimate wet tunnel must be the Severn? If the rigid bar system works well there then won't it work almost anywhere?

That is what the HS2 team are hoping they can do in adjacent Bradway Tunnel as lowering the trackbed would take time and a lot more cash. But there is a fairly easy diversionary route for whatever needs doing there, completion scheduled for 2033. No bets being taken on achieving that.

 

[Ploughman]

The HOPS train ordered for the GW electrification included moveable barriers which were intended to allow work to be done with the adjacent line open. Clearly this train didn't deliver the planned efficiency but I don't think that's a reason to abandon any hope of electrification with adjacent line open in the future.

However if it's a question of lowering the track in the tunnels that could be another matter - I can't imagine one track being dug out below formation level while trains are running on one a few feet away.

Surely the ultimate wet tunnel must be the Severn? If the rigid bar system works well there then won't it work almost anywhere?

Over the years many machines have been brought in to work on renewals of all types.
Talking here of Tampers and Ballast Cleaners etc.
It has been stated that most of these machines are capable of and are equipped for single line working.
But when it comes down to getting the Method Statement through the planning procedure you find that single line working has disappeared.
Even excavators fitted with slew locks have had to be rejected, reason given on that one was you might get a homicidal digger driver who could burst the slew lock and hit a train on the other road.