View Full Version : Railway query

Krystal n chips
29th Jan 2006, 18:02
Two questions please for any rail enthusiasts on here.

The first is, why, when a track is deemed fit to carry freight traffic, it has to be upgraded to carry pax ? I've always been curious about this as I would have assumed that the standards of track/ signalling etc would be the same irrespective of the operation.

The second question is because I am just plain curious. On the A5 just outside Oswestry, you encounter a clearly disused track, but with modern barriers and signals / signs etc. What was it used for and when did it cease operation. I use the road frequently hence my reason for asking.

Evening Star
29th Jan 2006, 18:27
It is possible to tolerate lower track standards for freight operation. Typically the upgrade for passenger operation is to allow higher speeds, or at least to eliminate speed restrictions that are not irksome for freight operation but would be a problem with a passenger timetable. As for signalling, it is permissible to operate freight under permissive block, but this is not normally acceptable for passenger workings so a signalling upgrade to absolute block is required where a previously freight line is proposed for regular passenger use.

As for the line near Owestry, if I am thinking of the same line that would the former route to Blodwell Quarry. Cannot recall without checking when it ceased operation or if there is a presevation attempt for the line.

29th Jan 2006, 18:56

In respect of your first question, track is maintained to standards that depend upon annual gross tonnage, and speed.

Differing standards for freight and passenger lines, in part, relate to the 'quality' of the ride of a passenger vehicle. This is a direct correlation between what we call "top" (i.e. the variation in height along the longitudinal section of the rail), and "Line" which is the variation in lateral displacement of the rail.

Different railway vehicles respond in different ways to variations in Top and Line. If we take a perfectly straight section of track in 100% condition then a passenger vehicle will run perfectly and almost feel to be stationery to those inside.

If we then introduce defects in the Line of the track, this will manifest itself by way of the vehicle jerking sideays. This is because the bogies are 'hunting'. i. e. they are wavering back and forth between the rails.

If we introduce defects in the Top, then the affect will be to cause the vehicle to bounce up and down.

If we introduce both then you get a particularly rough ride.

The art of track maintence is akin to controlled dilapidation whereby you try to keep the track within acceptable tolerances before it is due for renewal.

As a very general rule, modern track on concrete sleepers will require complete renewal at about 25 years depending upon tonnage and the type, and condition, of the underlying ground. Rails may well be replaced at about 10/12 years depending again upon the amount of use, and whether they are on tangental or curved track.

The degree of roughness will of course vary with the amount of variation there is in Top and Line.

I hope that is not too confusing but I have tried to simplify greatly something that is extremely complex.

If you want to know any more PM me and I will let you have some documents on track maintenance.

In terms of signalling nowadays there is very little difference between passenger and freight lines. There is still a requirement to provide 'Trap Points' where a freight line or loop converges upon a passenger line. Their purpose is to derail a train that runs towards the passenger line. This is not allowed where passenger tarins operate on such a line. A further issue could be that the signalling overlap, which put simply is a protected area ahead of a signal to prevent a collision in the event of passing a signal at Danger will either be reduced or non-existent on a true freight only line. Again a very complex subject considerable simplified.

In respect of your second question the line is disused and is part of the old line that ran from Gobowen through Oswestry into Wales. I believe it is the old Pen-Y-Coed branch but the passing of time dulls the memory. I shall enquire as you have whetted my interest now.

Evening Star
29th Jan 2006, 20:04
Think Astrodome is using an older atlas than I did! Can confirm that line to Blodwell Quarry started at Gobowen, so we are talking the same line. Checking my pre-grouping atlas shows that the line between Gobowen and Oswestry was GWR, with a spur to various branches of the Cambrian Railway and ultimately a connection to the Cambrian 'main line' between Shrewsbury and Machynlleth.

Did a Google and found this: Cambrian Railways Society (http://www.cambrian-railways-soc.co.uk/). They are the group based in Oswestry that I was thinking of in my earlier post. Notice the site mentions a branch line project to Nant Mawr, being the former station short of Blodwell. Apparently the line was mothballed for nine years prior to acquisition by the society in 2004, although the mothballing would account for non-removal of barriers and such like. Does this line fit your description KnC?

BTW, good answer Astrodome ... more detail then I dared to write!:ok:

29th Jan 2006, 20:39
Good answer Astro, now what is a 'Cyclic-Top' when it is around?

Captain Airclues
29th Jan 2006, 20:46
I'm afraid that I can't answer your query. However it brought back memories, as my father compiled the 1st edition of British Railway Track, which is now in it's 7th edition. When he died I donated all of his PWI literature to Peak Rail at Matlock and the money raised went to help open the line to Rowsley South. (sorry for the thread creep)


henry crun
29th Jan 2006, 21:28
I know nothing about railways but I do have a 1958 motoring atlas of GB, price 7 shillings and sixpence.

It shows a line from Gobowen to Ostwestry (alongside the A483) and on to Morton where a deadend line strikes off to the west more or less following the B4396.

The line going south through Ostwestry also branches off to the NE to Whittington and Ellesmere.

Is that any help ?

29th Jan 2006, 22:00
Thank you.

Cyclic Top

Cyclic top is the term used to describe a series of regular dips in the vertical alignment of one or both rails.

They have the potential, when combined with a vehicle's natural vertical response for a given speed and load to cause a derailment.

This effect can best be seen on jointed track where, over time, the rail joint dips. These joints are 60 feet apart.

If you remember back into the 1970's and 80's we had a lot of derailments to swb freight wagons which resulted in certain wagon speeds being reduced from 60 to 45 and latterly to 35 mph.

These derailments were caused by the vehicle effectively commencing a bouncing (and sometimes a rolling bounce) response to a repetitive dip in the rail.

Unfortunately many of the two-axle wagons had a wheelbase of approximately 21 feet, which was the natural rythmic response frequency of that type of a vehicle travelling at 60 mph.

Thus on jointed track, the vertical response of the vehicle to cyclic top resulted in them bouncing out of the four foot.

Cyclic top starts where there is a dip in one or both rails. The dynamic response of the vehicle will set up a bounce from that dip. Put simply the wheel will then impact upon the track at a point further along, which will then introduce a new dip. The distance will be a function of the vertical response of the vehicle based upon type, speed and load.

The second dip will then create a third, and so on, each dip being the same distance from one another. In the worst case this will in turn set up a vertical response in the vehicle and then will ultimately lead to a derailment.

PS ...Its my job !

Evening Star
29th Jan 2006, 22:17
the 1970's and 80's

My understanding was that the problem was first noticed in the 1960's, and there were a number of fanciful theories as to why it should be a problem with diesel hauled freight until the day a similar derailment occurred behind a 9F <ahem>. Certainly, the more consistent speed control one gets from a diesel (or a powerful steam loco for that matter) does seem better placed to provide the resonant conditions leading to this type of derailment.

Makes me very wary of the Class 14x series. Aside from the lack of safety demonstration provided by the Winsford Class 87 shunt (lucky it was ECS), the nodding donkey effect always feels like (I know, just an impression as the clever people at Derby solved that) a derailment looking for a cause.

29th Jan 2006, 22:37
Evening Star
There was a derailment at Roade when a 16t swb wagon dropped off and derailed a train which was then struck by one of the then new Class 310 EMUs.

This lead to a reduction in speed of that type of wagon from 60 mph to (I think 50 mph).

The real work into understanding cyclic top and wheel/rail dynamics followed on from that.

The Class 14x situation is (or was ?) a perfect example of a vehicle response to poor quality track. I have managed to avoid travelling on one of them for maybe 13/14 years now.

Krystal n chips
30th Jan 2006, 06:19
My thanks to all concerned for the excellent and detailed replies. :ok:

I have a couple of questions in response, however, I will post these later as work calls in the very near future hence my time is limited at present.

Once again, my thanks for the detail in the answers. :ok:

Shaggy Sheep Driver
30th Jan 2006, 11:00
In terms of signalling nowadays there is very little difference between passenger and freight lines. There is still a requirement to provide 'Trap Points' where a freight line or loop converges upon a passenger line. Their purpose is to derail a train that runs towards the passenger line. This is not allowed where passenger tarins operate on such a line.

Wasn't the Winsford accident caused by lack of trap points or flank protection? The 'nodding donkey' (ECS, luckily) ran past a 'red' and then through the trailing points, which put it on the down fast in front of class 87 'Wolf of Bandenoch', which was running at speed and hit the nodding donkey from behind, all but demolishing the rear coach.

By the way does anyone know what is being done on the WCML Crewe - Cheadle Hulme section, which is closed 'till end of March? I know there is signalling work being done, but it appears a lot of track replacement is happening as well. Are they replacing ALL the track or just certain sections?


30th Jan 2006, 11:49
SSD I believe they are "uprading" the tack, you know, the same work they have been doing for the past thirty years:rolleyes:

30th Jan 2006, 12:00
You lot are now growing Emus big enough to derail a train???? Not sure I want to see the egg then, could feed a whole village on one:E:E

(Helmet & Bike , I know the drill)

30th Jan 2006, 12:12
My thanks to all concerned for the excellent and detailed replies.Absolutely delighted to be of assistance. Always happy to pass on knowledge. Please feel free to PM me for anything you feel may be too complex to put on here.

Wasn't the Winsford accident caused by lack of trap points or flank protection?

The particular location you refer to at Winsford was the Down Slow to Down Fast junction.

As this is signalled for passenger trains there are no trap points.

There are a number of Good Lines/Loops along the WCML that do have trap points but these are designated as goods lines and should not be confused with adjoining Slow lines.

Shaggy Sheep Driver
30th Jan 2006, 12:26
Thanks Astro. I'd missed that.

I read somewhere that railways (even before privatisation) were saving money by taking out flank protection at many junctions.

The Colwich collision in particular is one which would not have happened if such protection had been in place.



+'ve ROC
30th Jan 2006, 12:34
The line itself if disused and has been for years but I've no idea why the modern crossing equipment is there.

South of Oswestry it runs past Llnclys pool and then follows the road which meets the A5 at the 'White Lion'

Parents have got a cottage on Llynclys common and many an evening was spent hobbling over the disused tracks to get to the pool for a spot of fishing.:ok:

As I recall a good section of the track has been ripped up and sold for scrap metal.

30th Jan 2006, 12:37
SSD No worries, mate.

As for flank protection now that is a different subject.

Whilst being one who opposes very much the principle of removing flank protection by installing single lead junctions, it is a matter of hard fact that the financial situation will always have a high profile when junction renewals come up.

Elsewhere on an earlier thread we had the rantings of someone who was opposed to paying what they considered to be an extortionate price for their rail ticket. People with similar attitudes are to be found all over and place great store upon 'cheap' travel.

Strangely enough they are the very first ones to start shouting about safety when an accident happens.

Krystal n chips
31st Jan 2006, 06:59
Please see PM's.

Re the line outside Oswestry, I went past it yesterday and had a closer look--plus a Google and the Cambrian Railways link supplied here:ok:

I would indeed appear to be the spur line from Gobowen that formerly ran into the town. I cross the main line at Whittington ( coming from Whitchurch on the A485 ) so this makes sense given the direction it runs. So that's sorted that query--my thanks for all the reponses :ok:

31st Jan 2006, 10:54
Can I drag you from the west to the east for a moment? During my travels I have ended up a couple of times in Boston, Lincolnshire, which is on the branch from Grantham to Skegness. In Boston there is a (small) goods yard with a tiny little spur that used to run out to the docks. These days, though, this tiny spur crosses the main road into Boston from Spalding and continues for 30 or 40 yards, then stops (by a disused Octagonal signal box - interesting in itself). The thing is that nothing crosses this road, surely, as the line goes nowhere and yet there is a full automatic crossing right there across the road. How much does it cost to install (and presumably maintain) equipment like this that surely is never used? That money could be better spent elsewhere, don't you think (like on maintaining the track properly between Boston and Skegness which has, apprently, just been downgraded...)? Why not just end the spur before it meets the main road?

Do any of you knowledgable railway chaps and chapesses know about the lines in that particular part of the world?

31st Jan 2006, 11:10
For details of the current track structure see: Rail Atlas Great Britain & Ireland by S.K Baker (ISBN 0-86093-576-0).

At Boston it shows a short spur annotated 'Docks - Port of Boston Authority (Lafarge Redland Stone Terminal)'.

On the NW side of the town it also shows the carriage sidings and fuel point.

31st Jan 2006, 17:39
Although the equipment will still be there, the fuses in the control cabinet will have almost certainly been removed.

The situation is that it is not normal to recover this type of equipment unless the line is taken out of use for an extended perid.

Until recently there was quite a long drawn out, and very public process for closing railway lines that generally precluded closing them if traffic has ceased. In many cases, the line may well be retained fir future traffic.

Not all railway in the UK is controlled by Network Rail so some lines could well be in private ownership.

I believe this is the case in Boston Docks.

31st Jan 2006, 19:02
Thanks guys, for taking the time to answer.

Romeo Charlie
31st Jan 2006, 19:36
The Boston Docks branch was certainly in use 2 years ago when I worked as a controller for EWS. It used to get a twice weekly service from Mountsorrel (I had to provide the locomotives). It is a private branch and Lafarge used to own a pair of small diesel shunters to take the trip from Boston Goods down the branch to the docks.

I am no longer in EWS's employ (or in Rail Freight for that matter) so the situation may have changed somewhat.

Barry Coomer
31st Jan 2006, 20:26
The Crewe-Cheadle Hulme blockage is happening because they are closing two signalboxes : Sandbach and Wilmslow, both are PSB's (Powersignalboxes) from the '70's which are well passed thier sell-by date !
All signalling equipment is to be replaced and controlled by a "relatively" new signalbox called Manchester South, situated just outside Stockport station.

I work in a PSB which was built in 1972 ! Thankfully nobody is that interested in upgrading North of Crewe, so we should be here a while longer.

31st Jan 2006, 20:58
Barry Coomer
Ah ! Warrington one suspects ??

If so, many years ago I worked in BY and we had a Signalman that came from that part of the world in 1984/5.

He trained BY as a D and during which time he applied and got an E at Warrington.

He did one shift, owing to the sickness of the late turn man, after passing out. I don't think he was much impressed as he wanted to get away, and it was a Saturday as I recall ! Mind you I effectively worked the panel for him !!

Cannot think of his name now.

If you were about then and remember the man, do PM me ?

Shaggy Sheep Driver
31st Jan 2006, 21:28
Regarding Crewe - Cheadle Hulme, I know about the signalling thanks chaps, but I took a look recently and they are ceratinly replacing the track at Wilmslow and Alderley, right down to the sub-base (old track cut up and discarded, bulldozing the soil, replacing with new sections of track and re-ballasting).

I just wondered if they are replacing the whole mileage, or just certain sections. Certainly when I drove through Chelford last week it looked like track replacement was happening there as well.

Anyone know how extensive track renewal will be during this closure?


Barry Coomer
31st Jan 2006, 22:05
Warrington would be correct.
I have 'only' been here sice 1994. However, one guy in here reckons he might know. Barry Robinson ring any bells ? If you think of the name PM me.
The Manchester line job is supposed to be two months behind schedule, by the way. Something about loads of contractors getting the sack by Notwork Fail (?) who promptly took their machinery away, hence no more relaying.
You really couldn't make this stuff up !!

31st Jan 2006, 22:29
Knowing those concerned, I was stunned at that they were awarded the work.

It was all based upon price.

Unfortunately NR are STILL unable to correlate crap work with cheap price.

The manager who awards is on a large bonus for cheapest tender award, and the Project Manager is on a bonus for minimising the inevitable contract variations.

Inevitably the original tender price plus the CVs are always more than using a more efficient, and competent contractor whose price is slightly more than the original for that very reason !

Time and time again we raise this to NR and it is always the same cheapest wins irrespective of the true long term cost.

As an old BR man, time retirement and Spain cannot come quickly enough