For a variety of economic reasons, BR has always considered the 2-axle wagon to be preferable to bogied wagons when the commodity to be carried allowed. At all times, bogie wagons developed in similar ways to 2-axle types but the design of bogie was largely influenced by private companies at home and abroad. From the early 1960s to the late 1970s, BR bought in proprietry bogies, but in the late 1970s Derby Locomotive Works was set up to build the French-designed Y25C bogies, and BR developed its own design for export in 1982.
(Quote from
An Illustrated History of BR Wagons, Volume One, OPC 1985)
I just wanted to come back to this thread with some information from a book I've been reading: Geoffrey Freeman-Allen's
British Railfreight - Today and Tomorrow published by Jane's in 1984. This is the book I was thinking of which mentions the French Y25C bogie as a big factor in changing the economics of bogie wagons. All the long quotes in boxes below are from that book.
French Railways' decision in the late 1970s to eliminate the two-axle wagon from all future wagon building - which they have since rescinded, incidentally - encouraged the local industry, backed by a scale of orders unimaginable in Britain, to develop an expertise and economy in bogie wagon design lacking in the UK, where BR and user alike then mostly favoured two-axle vehicles. A particularly beguiling attraction was the French Y25C freight wagon bogie, which even Procor is now importing to serve its own construction, though it needed some modification before it was comfortable to run on British track.
Quite why things like cement tanks and aggregate hoppers were built as four wheelers I don't know.
David Ratcliffe's book
Modern Private Owner Wagons on British Rail published by PSL in 1989 lists the batches of different types of private owner wagons built for the UK. Talking about cement wagons, he mentions that
"Only two fleets of bogie presflos have been built, most operators preferring the greater flexibility offered by two-axle vehicles."
The 2-axle PGAs for aggregate traffic were built in volume up until ~1980, plus some more after that for the Redland self-discharge trains.
By the mid 1980s there had been surprisingly few bogie hoppers for general aggregates built in the recent past, just a couple of small batches for specific London-area flows:
>1968 for Murphy aggregates (Angerstein Wharf) 102t GLW, 75t cap, 51ft length (GLoucester Cast Steel bogies)
>1970 for Brett (Cliffe), 102t glw, 73t cap, 42ft length (Gloucester Mk4 bogies)
Going back much further to the 1930s, there were the famous "hoppers" built for the Tunstead limestone traffic. I suspect a key reason those were built as bogie wagons was that they only had to serve a small number of specific terminals where the size didn't cause an issue. As a comparison, David Larkin mentions in
Working Wagons Vol 2 that the BR-built 50 ton capacity "Whale" bogie ballast hopper
"proved too large for general use"
In 1984 there were some aluminium-bodied bogie hoppers built for Yeoman; I seem to recall there were some issues with the aluminium bodies and they were scrapped after a fairly short life. In 1984 a small batch of 88t glw wagons appeared for Hall aggregates for traffic out of Newhaven, which later migrated into the RMC fleet out of Peak Forest. These had the French Y25 bogies, and were followed in 1986 by 90t glw wagons for Bardon Aggregates and 88t glw wagons for RMC, also with the Y25C bogies. I remember the Bardon and RMC fleets as being very modern-looking, and these types of wagons paved the way for later fleets of bogie hoppers.
In the mid-1970s most of the aggregate firms opted for lease of two-axle, 51-tonne glw hoppers to form their wagon fleets. This was rarely a case of terminal layout limitations debarring use of bogie wagons with the higher payload/tare ratios one would have thought so critical to transportation economy. The deciding factor then was the diproportionately high first cost of a bogie wagon and of bogie maintenance.
The cost balance began to change in the sharply in the 1970s. The key factor was the French wagon industry's perfection and mass production of its Y25 family of bogies - with, it must be added, market backing of a kind not enjoyed by British industry. Tiger Rail... was the front-runner in introducing to the UK French-built 88-tonne glw wagons mounted on these bogies.
Those were the well-known "Clay Tigers" operating out of Cornwall. Due to economies of scale, apparently the French-built 88 tonne glw bogie aggregate hoppers based on this design were only 20% more expensive for 75% more payload than a PGA.
Looking at tank wagons in
Modern Private Owner Wagons on British Rail, there were a large number of 45 tonne glw TTA tanks built in the 1960s, due to an increase in maximum axle weight on BR to 22.5 tons in 1962 coinciding with the signing of long-term contracts between BR and the oil firms in 1963.
The axle weight on certain routes was raised to 25.5 tons (in 1966 I think?) and after a 1966 prototype, bogie wagons of 102 tonnes glw were introduced from 1967 onwards - by 1969 Shell & BP together had over 1000 bogie tanks. There were relatively few two-axle tanks built for petroleum after the appearance of the bogie tanks, although a few TUA designs appeared in the 1970s, using the extra permitted axle weight.
I think the size of coal wagons in general were somewhat constrained by the layouts of coal loading points. The development of the MGR concept gets a chapter in
Milk Churns to Merry-Go-Round: A Century of Train Operation by R.T. Munns, a BR manager at the time. He also mentions that
"Having regard to payload/tare ratio and the desire to have instantaneous discharge through bottom doors it was found that a two-axle design was superior to the use of bogies".
***
Going back to Speedlink-era vans, this passage from David Ratcliffe's
International Train-Ferry Wagons in Colour (Ian Allan 2009) is interesting:
"Bogie vans had never been common in Britain because so much of the Victorian infrastructure at goods depots and private sidings was inaccessible to larger vehicles. However, this changed in 1977 when German wagon-leasing companies Cargowaggon and VTG both introduced 80-tonne-glw bogie ferry vans for service between the continent and Britain...For their day they were real monsters". The two designs mentioned were 62ft and 71.5ft long, and they do look very anachronistic when you see photos of these huge bogie vans sat outside old warehouses which still display the names of pre-nationalisation companies.
Returning to
British Railfreight - Today and Tomorrow:
Cargowaggon is... best-known in the UK for its splendid sliding-wall bogie vans. It employs specialist industry to build its vehicles, but the design is done in its own engineering department - which, incidentally, seems to have been the mainspring of Speedlink's latest two-axle sliding-wall van concept, the VGA, built by BREL.
*
Cargowaggon's managing director... is also concerned at the state of many existing sidings, which he regards as unsuitable for bogie wagons until they have had track rehabilitated and curves realigned.
The same book has a contemporary (1984) list of Speedlink-served terminals, over 100 private sidings plus 100 BR facilities. The private terminals have codes showing facilities available, and this also specifies which of these terminals are suitable for "high-capacity" wagons. It appears that most terminals were able to accept these kind of vans, but clearly the sheer size of bogie vehicles was still a consideration.
It is also interesting that many of the two-axle Speedlink opens and vans were built to run at 75mph provided the load did not exceed certain weight limits. This possibly had an influence on bogie vs two-axle designs. 75mph freight bogies would have been in use on Freightliner flats but not much else.
In the early days BR's Speedlink publicity made much of the 75mph maximum speed at which merchanise would henceforward glide unimpeded across country in the new air-braked wagons. The private wagon industry soon bridled fiercely at the extra cost of making their vehicles fit for this speed...
A later chapter on Railfreight International seems to turn BR's preference for two-axle wagons on its head. Speaking specifically about international traffic via the train ferries:
The only present concern is an over-supply of two-axle box vans, since the aim is to work to the maximum with bogie vehicles, flat or open as well as covered, for general merchandise cargoes.
I don't think the two-axle design of the speedlink-era vans was particularly bad, even in hindsight - the ideal fleet would probably have been a mix of VGA-style 2-axle and Cargowaggon-style bogie vans. It's interesting that the bogie "Taunton Cider" vans were apparently 'ousted' by twin-vans in 1989. Photo of a Taunton Cider van in a Speedlink formation here:
https://www.flickr.com/photos/freightcarkid/15892251704
The biggest problem with the various types of Speedlink vans appearing before the VGA seems to have been the layout of the doors (based on previous reading), which were not always ideal in terms of ease of loading. The VGAs had a much more streamlined sliding-wall arrangement of two doors allowing access to half the wagon at a time.
Going back to the initial quote at the start of this post, it looks like one of the biggest reasons for Speedlink-era vans being two-axle was that BR at the time didn't have a suitable bogie design of its own, and buying in bogies would have increased costs. A lot of BR-built bogie wagons up to that point (such as bogie bolsters for steel) had to be bogie wagons due to the length necessary to carry certain loads. The main exception I can think of would be the large numbers of Freightliner flats built a few years earlier. An earlier quote about the costs of bogie maintenace was probably also a factor in the choice of Speedlink wagons. A photo in one of my books, showing one end of a PGA wagon being hoisted up with a relatively small piece of lifting equipment, allowing the axle to be removed, illustrates the point.
It's sad to read about the heady growth projections of Speedlink traffic in the mid-1980s, considering the demise of the network in 1991. There are relatively few wagons from the Speedlink general merchandise builds remaining. OAAs are virtually extinct, and the OBAs and OCAs still in use on departmental traffic may end up being replaced by the new modular wagons (based on container flats) for Network Rail. The builds of VAA/VBA/VCA and subsequent conversions appear to be extinct, with a tiny number of VDAs or ex-VDAs surviving as generator vans. Large numbers of the Speedlink vans and opens were converted into ZCA Sea Urchins for departmental use, and also into OTA timber wagons, but even these have since disappeared.
A small fleet of VGAs remains in traffic on a wire-rod-in-coil flow from Cardiff Tidal to Burton, seen here at destination:
https://www.flickr.com/photos/149450236@N06/51268310471
Even the various types of Carowaggon bogie vans are now rare in the UK. Some IWA "holdall" vans are in use on Ditton to Germany aluminium traffic. The Cargowaggon branding is faded, and they appear to be on hire from Touax (formerly Tiphook):
https://www.flickr.com/photos/dan700/43498037761/
The IZA twin-vans used on the water trains from France to Daventry also appear to be hired by Touax:
https://www.flickr.com/photos/dan700/40477007775/
I can't think of any other "Cargowaggon" type vans in use in the UK, except for a few IWAs used as coupling adaptor wagons on movements of new units to the UK, seen in the formation of a Class 777 unit move here:
https://www.flickr.com/photos/153305438@N06/51688397243/
