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Meldon Viaduct


Guest Jack Benson
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Ok Jack, I'm feeling generous so I have dug out the SR locomotive restriction book for Dec 62. Meldon viaduct itself wasn't particularly more onerous in restriction terms than other places on the route so this is based on the limits for Okehampton to Devonport Junction. Where Meldon has a specific influence I'll mention it.

 

No locos coupled together are permitted to cross Meldon viaduct.

 

Classes barred between Okehampton and Devonport Junction,

W, K, G16, H16, MN, N15, S15, V, Clan, Brit, DoG, 9F, 15xx, 16xx, County, Castle, Grange, Manor, Black 5, B1, LMS & SR diesels, Metrovick Co-Bo, NB Warships.

 

Max speed whole route 40mph.

8F and WD 2-8-0

 

Only permitted when SR/WR diversion arrangements in force and 5mph over Meldon viaduct,

Std 5, Hall, 61xx

 

10mph over Meldon viaduct,

Deltics

 

A number of former GWR classes needed footsteps cut back and some local speed restrictions, 22xx, 43xx, 57xx, 45xx, 51xx, 61xx, 81xx.

 

The Deltic seems wholly unlikely but that's the railways for you, basically if it existed in Dec 62 and it's not mentioned above then it was allowed between Okehampton and Plymouth without restriction other than overall line speed.

 

That's it, a Happy New Year to you all when it arrives.

Best wishes

Martin

Edited by Martin Shaw
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Guest Jack Benson

Hi,

 

Thanks for filling in a black hole of knowledge, the period of interest is the early years of BR.
 

May I ask if Exeter Queen Street was a ‘boundary’ for services between Waterloo and the West of England?

The query is driven by a comment elsewhere that suggested that the exLSWR D15 had been used on the Plymouth-Brighton service until replaced by BLPs but there was no hint whether the D15 had been used west of Salisbury. If D15s were permitted to cross Meldon, maybe they had been used on the entire service? 

 

Btw, I am no WR expert and I am surprised that the Manor was banned and that there is no mention of WR’s Kings and the heavier goods classes but were these classes allowed west of Exeter on the WR’s own metals? 
 

Thanks once more

 

Happy New Year

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There where restrictions on BR(s) from a lot of the outside cylinder locos as they fouled the platform edges. I seam to recall a Hall turning up at Redhill by mistake. It had to be sent back in an over night possession at ver low speed.

 

Keith

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I think by the the Dec 1st date of the publication all of the King class had either been withdrawn or were limited to services that wouldn't or couldn't access the SR as it stood at the time, that is Padd - Wolverhampton. I may be wrong on this so don't quote me.

 

I don't think Exeter was a boundary for SR services but in particular you have to be aware of what restriction a stretch of line imposes, it can be weight (axleload) or loading gauge or a combination. In the case of ex GWR locos width over the cylinders is a more critical factor than axle loading, something modern like a Schools will have a very high axle load but for obvious reasons isn't going to be troubled by platforms or bridges. In that respect a D15 is heavier than a T9 but lighter than a Schools and the D15s would probably have been okay however according to Bradley they were barred from the Brighton to Bournemouth, Cardiff and Plymouth services by the restrictions on the river Adur bridge at Ford. In the 1930s there were a couple at Salisbury and they got as far as Exeter, I can find no reference to them further west.

 

The GWR heavy goods engines 28xx and 47xx were permitted west of Exeter by the SR route, the Manors not so, presumably width over cylinders again.

 

I hope that answers your queries.

 

Regards

Martin

 

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Whether or not it has any relevance in this context, but the Western Appendices dated 1934 mention maximum loads of passenger trains between Yeoford and Plymouth Friary.

The classes mentioned are N, S11, K10, L11, and T9.

 

Does the absence of a mention of other classes mean they were not permitted, or simply that they were not expected to run over that route?

 

cheers 

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Guest Jack Benson

Martin,

 

My best guess is that the D15 ran as far as Salisbury or even Fratton on the Plymouth-Brighton service where it handed its charge to a loco permitted on the Adur Bridge. However, this was very much a limited service as the D15s were primarily in use on the Bournemouth and Portsmouth direct (pre-electrification) routes and only ten in the class.

 

My use of the term boundary is somewhat misleading, I could not think of anything to describe that some SR  classes did not usually venture beyond EQS. However, the S15/N15/H15 was permitted to Okehampton for stone traffic but that is uncertain when this began as BLPs certainly took charge of stone traffic from the 50s onwards. 

 

The reason for this query began with the group's layout based on the proposed Dorchester & Exeter Coastal Extension, there is a wee bit more information here
 

Thanks to all that have contributed to the thread.

 

Happy New Year

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The WR June 1963 Route Availability Booklet list the following as authorised between Exeter and Plymouth via Okehampton for normal working provided the width over engne footsteps does nnot exceed 8ft 4". (N.B. Former SR classes were still covered in an SR publication at that time).

 

Coupled working of engines over Meldon Viaduct prohibited except in the case of loco failure.

1st list  - 32XX, 57XX (not 9700 -10), 55XX (subject to restrictions at various locations including some station platforms), 41XX (but not 61XX).  BR Standard 84XXX,  82XXX, 78XXX, 77XXX, and 76XXX

2nd list -  D8XX, D63XX, D70XX..  D6XX only permitted to work between Devonport Jcn and St Budeaux Victoria Road.

3rd List - D10XX Subject to 10mph over Tavy Viaduct and Camel's Head Viaduct 

 

Effectively the earlier SR list barred all GWR Red Group engines from the line so obviously 'Kings' would also have been barred and they were in any case barred from access to any SR lines west of Devonport Jcn at Plymouth.  They were permitted west of Plymouth North Road to only Millbay and Keyham and even then, until October 1948,  were subject to a 10 mph restriction over the bridge at the west end of Plymouth station.

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On 31/12/2020 at 22:04, Martin Shaw said:

according to Bradley they were barred from the Brighton to Bournemouth, Cardiff and Plymouth services by the restrictions on the river Adur bridge at Ford.

 

Are you sure you mean the Adur? as the bridge is at Shoreham, the bridge at Ford is over the Arun.

 

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ISTR the skool quadrangle discussions said the Schools were the heaviest 4-4-0s in Europe, and I don't think they ever got into far-Devon at all. The light pacifics had excellent route availability. Per-axle weight was the CCE's yardstick above all for bridges, I think. RA is a complicated subject, though. 

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On 31/12/2020 at 22:04, Martin Shaw said:

Bradley they were barred from the Brighton to Bournemouth, Cardiff and Plymouth services by the restrictions on the river Adur bridge at Ford.

 

:offtopic:

 

 

I believe that restrictions were eased when the Southern Railway rebuilt / strengthened said river bridge at Ford in the run up to the 1938 electrification of the mid Sussex / coastal lines between West Worthing and Portsmouth.

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23 minutes ago, SD85 said:

I don't quite understand how the K and Schools classes were banned while the obviously larger Light Pacifics were allowed on the route (and the heavier rebuilt engines were permitted from 1960).

The West Country class had a significantly lower axel loading than the Schools. 

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I think we are in general agreement that of the SR locos then extant the Schools will have the highest axle loading, even though they may not be the heaviest locomotive so just for a bit of fun I have made a list of routes where the Schools were prohibited. It can be taken that the former LSWR G16 and H16 classes were generally similarly limited by weight and the SR Z class had excessive front and rear overhang on curves which also had a bearing on loading gauge acceptability. MN and rebuilt WC had some limitation, original WC could pretty much go anywhere on a main line. I don't mind answering specific queries but I'm not going to reproduce the whole document so don't even think of asking.

Regards

Martin

 

Schools class route prohibitions.docx

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That's a very interesting list. Having grown up in Paddock Wood it caught my eye that the Schools were prohibited from the Maidstone West line (at least the southern end) - but not (by omission from the list) the Hawkhurst branch. I am guessing that this would be due to the bridges over the Medway at Beltring. 

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With 21 tons each on a pair of axles 10ft apart I reckon the Schools would have been pretty horrendous when it came to a Bridge Curve measurement.  The H16 came out at 19t 12cwt on the three driving axles over a total of 15ft.  Apart from the trailing driving axle at 17t 10cwt the G16 was either 18t 10  cwt or 18t 9cwt over its three leading driving axles.  And at 9ft 2" overall width these two classes were some of the widest engines on the Southern which can't have helped their route availability either.

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Guest Jack Benson

What was the actual axle loading limit for Meldon?
 

It might provide a clue to the reasons why other lines were unable to be traversed by certain classes. In my case, it is the S&DJR between West Moors and Alderbury which included the bridge over the Avon at Woodgreen. The persistent belief is that the S&DJR had a similar restriction as Meldon but actual verified knowledge is anecdotal.
 

StaySafe

 

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