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Work on Hope Valley line approved

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Class 170101

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How long is the loop itself? Would access and egress to the loop plus its length be restricted in such a way that the freight would have to be brought to a stand in the loop to allow a second train to pass or is it possible for the freight to traverse the loop at a sufficient speed whilst a faster train is passing on the main line and then the freight to pull out behind the faster train without it being from a standing start?
 
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XDM

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How long is the loop itself? Would access and egress to the loop plus its length be restricted in such a way that the freight would have to be brought to a stand in the loop to allow a second train to pass or is it possible for the freight to traverse the loop at a sufficient speed whilst a faster train is passing on the main line and then the freight to pull out behind the faster train without it being from a standing start?

Afraid not. It is not a dynamic loop. It is a recessing loop to hold a 640m freight train. It is the cheapest NR can get away with whilst getting the acclaim for spending millions on upgrading the line. And no doubt it will cost a kings ransom.
The ideal operating location, Grindleford, would have cost more but I reckon, as a non engineer, from looking at the excellent maps Dom245 provided that it might be possible to contain the loop in BR boundaries in the way that the WCML was quadrupled near Tamworth with nails driven into the cutting to make it steeper.
 

furnessvale

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How long is the loop itself? Would access and egress to the loop plus its length be restricted in such a way that the freight would have to be brought to a stand in the loop to allow a second train to pass or is it possible for the freight to traverse the loop at a sufficient speed whilst a faster train is passing on the main line and then the freight to pull out behind the faster train without it being from a standing start?
That would be a dynamic loop and considerably longer than that proposed.
 

Domh245

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How long is the loop itself? Would access and egress to the loop plus its length be restricted in such a way that the freight would have to be brought to a stand in the loop to allow a second train to pass or is it possible for the freight to traverse the loop at a sufficient speed whilst a faster train is passing on the main line and then the freight to pull out behind the faster train without it being from a standing start?

The decision letter states says that the Bamford Loop will be about 1,062 metres long, so it definitely won't be a dynamic loop.
 

B&I

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Grayling isn't going to approve that. At least, not until it has been proved to him that his digital railway idea won't provide the capacity.


You are confusing Grayling with someone who is concerned with evidence, reality etc
 
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Joseph_Locke

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Within earshot of trains passing the one and half
(with a 66 hauling a 2550 ton load and crawling out of the loop at 15mph)

The loop S&C is 50mph, not 15. The slowest standard S&C unit in the catalogue is 25 anyway!

How long is the loop itself? Would access and egress to the loop plus its length be restricted in such a way that the freight would have to be brought to a stand in the loop to allow a second train to pass or is it possible for the freight to traverse the loop at a sufficient speed whilst a faster train is passing on the main line and then the freight to pull out behind the faster train without it being from a standing start?

The 1000m or so is toe to toe; the loop is long enough for the train, the minimum possible signal overlap and a small allowance for inaccurate stopping and signal visibility.
 

The Planner

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If its 1062m long, then that should hold a 775m train which is the standard that any new loop should assuming a 180-200m overlap.
 

Domh245

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If its 1062m long, then that should hold a 775m train which is the standard that any new loop should assuming a 180-200m overlap.

Interestingly, the decision letter suggests that the train length it's been designed around is 640m - although it's only mentioned because there were people arguing that it should have been designed for 520m long trains.



Coming back to the earlier discussions about the positioning of the loop, I decided to finally have a leaf through the inspectors report. It notes that a loop at Grindleford was considered, but rejected for the reasons quoted below. It is also interesting to see that, as discussed - Grindleford would have been the optimum operational solution but not the optimum engineering solution.

The Grindleford loop would be positioned along the northern side of the existing rail tracks a short distance to the west of Grindleford Station. In that location the northern boundary of the railway is at the bottom of a steep wooded slope, much of the woodland comprising Ancient Woodland202 . OBJ/33 suggested that if gabions were used to support the required embankments, it would be possible to undertake the construction works within a strip of land no wider than 15 metres from the nearest existing rail track [5.8.3, 5.8.7]. The suggested layout provided by OBJ/33 indicates that around 10 metres would be taken up by the new track and retaining wall, without any allowance for drainage infrastructure at the base of the wall, leaving only some 5 metres of the 15 metres for working space and access203 . Even if 15 metres were adequate, it is clear from the layout plan that many more trees than are identified as ‘trees to be removed’ lie within 15 metres of the nearest track. Based on what I have read and seen at the site, not least the challenging steep topography, I share the view of NR that far more than 15 metres would be required to make a reasonable allowance for the new structures as well as working space and access for construction plant, vehicles, materials and personnel [3.2.9-11]. Contrary to the view of OBJ/33, I consider it likely that a significant number of trees would have to be removed from the southern section of the neighbouring Ancient Woodland in order to facilitate the works.

7.3.16 Paragraph 118 of the Framework indicates that local planning authorities should aim to conserve and enhance biodiversity by applying a number of principles, which include refusing planning permission for development resulting in the loss or deterioration of ancient woodland, unless the need for and benefits of, the development in that location clearly outweigh the loss.

7.3.17 Whilst Grindleford would provide more operational flexibility, being closer to Dore, the evidence confirms that the Bamford loop would provide a workable alternative from an operational perspective. Furthermore, NR has indicated that in direct comparison with the Bamford proposal, built to accommodate a 640 metre long train, the disadvantages of the Grindleford loop would include, amongst other things, that it would be likely to be: longer, allowing for the transition between the curved alignment of the existing track and the loop; more difficult to access, not least due to the steep topography on the northern side of the tracks; and, as a result of these and other factors, more expensive [3.2.12]. I have not been provided with any compelling evidence to the contrary.

7.3.18 It appears that, in comparison with the Bamford loop, the Grindleford option would be more remote from the nearest residential properties and so the likely impact of noise from the operation of the loop on dwellings would be likely to be less [5.1.12, 5.8.6]. However, the Grindleford alternative would be likely to have a significant impact on the noise environment experienced by users of the local footpath network, which I found to be tranquil in comparison with the Bamford site, where background noise levels are affected by traffic on the nearby A6187.

7.3.19 I consider it can be reasonably concluded on balance, without further investigation, that the identified Grindleford loop location would be unlikely to amount to a preferable alternative to the Order scheme. Any benefits associated with positioning the loop at Grindleford would be clearly outweighed by the likely loss of Ancient Woodland and other disadvantages [5.1.10, 5.4.3-7]. It would conflict with the aims of the Framework.
 

Class 170101

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Has any modelling been done of trains entering and leaving the loop to / from a stand as to how much capacity will be gained with it or whether like some posters are suggesting it will be an asset that will see very little use.

The reason for asking about whether it would be a dynamic loop or not (and thanks to those mentioning it as I'd forgotten the technical term) is presumably a slow moving freight is easier to get up to speed than one from a standing start.
 

edwin_m

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Yes a dynamic loop would be better but dynamic overtaking loops are huge. Based on some simplified numbers:

The freight train would have to be fully inside the loop with the passenger train at least a mile away so it could still run on clear signals. Let's say also that the pasenger train needs to be a mile ahead of the loop exit before the freight leaves the loop (in practice the first figure will be a bit more than a mile and the second will be a bit less).

Therefore the passenger train has to travel an extra two miles plus the length of the freight train, the signalling overlap at the end of the loop and its own length, say 3 miles total. If the freight train travels at 30mph (slow) and the passenger at 90mph then, using time=distance/speed and the length of the loop being l:

(l+3)/90=l/30
l=1.5 miles, or about twice as long as the static loop

Increasing the freight speed to 60mph the loop goes up to 6 miles.

This is a very crude calculation and in practice the loop would probably be longer to account for things such as late running of the trains.
 

PhilipW

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Is there to be both a westbound and an eastbound loop, in effect making the layout 4-track for a few hundred yards, or is the loop in one direction only ?
 

snowball

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Is there to be both a westbound and an eastbound loop, in effect making the layout 4-track for a few hundred yards, or is the loop in one direction only ?
The proposed loop is one-way. There's an existing loop the other way elsewhere.
 

edwin_m

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I think the layout at Earles Sidings can be used as a loop for westbound freight, although it's rather short. There's another eastbound loop at New Mills South, but only for trains coming from Marple.
 

Dr Hoo

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Most Westbound freights are running with empty wagons, so rather faster. They are also most likely to be 'turning left', so fewer conflicting moves.
 
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