Wagon wheelbases

[TravisM]

The two axle, 9ft wheelbase was the standard length for most wagons but why did it last so long?  I would have thought that longer bogie’d wagons would have been introduced in the 50’s more quickly than they were.  It seems that the 60’s onwards that they seem to become common place and the last two axle wagons built were HAA’s and it’s different variations.

 

It seems that the logical sense (to me) for coal traffic was something similar to what EWS  and Freightliner created as you didn’t need as many wagons and could carry heavier loads.

[doilum]

In the case of coal, all the infrastructure had evolved around that standardised wagon both at the colliery and consumer end. It took the development of the MGR system with rapid loading bunkers and moving discharge hoppers to provide the clean design sheet needed to change. At the same time coal exports were ending and the Victorian infrastructure became obsolete. No coincidence perhaps that the switch to coal imports and the move to bogie stock happen around the same time?

[The Johnster]

The railway companies had argued unsuccessfully for larger coal wagons since the Edwardian era, and were able to use hoppers or double door 21 tonners in some cases but had to attract customers with lower rates, negating the commercial advantages.  Wheelbases on other wagons gradually increased from 9' to 9'6" or 10' during the first half of the 20th century, and was encouraged by the gradual adoption of vacuum braked vans and wagons that could be used as tail traffic on passenger trains; these 'XP' branded vehicles had to have 10' wheelbase.

 

Bogie wagons introduced in the late 60s or early 70s were a response to the Beeching principle of block or intermodal trains, the basis of modern freight operations.  Prior to this, it was convenient to use the older 10t vans or 8t opens for general merchandise traffic as it was easier to fill the vehicles with loads different destinations and re-marshal the trains en route, providing a service from any goods yard (don't forget these were at every station above the status of a halt in those days) to any other goods yard within about 3 days, fulfilling the railways' pre-Beeching statutory obligation as a common carrier service at a government specified rate.  Of course, some block mineral trains had used high capacity bogie wagons long before this.  

[Wickham Green too]

14 hours ago, The Johnster said:

.......... Wheelbases on other wagons gradually increased from 9' to 9'6" or 10' during the first half of the 20th century, ............

While a few pre-grouping railways adopted 9'6'', 9'3'' or other intermediate wheelbases the 'big four' standardised on 9'0'' and jumped straight to 10'0'' in the thirties ......... apart from coal wagons and longer 'specials' ( small 's' ).

[31A]

As well as facilities for dealing with coal, there were a lot of railway goods depots and private sidings that had old fashioned facilities for dealing with general merchandise traffic and other goods.  Some of these included things like wagon turntables and hoists which could only accommodate short wagons; the increase from 9ft to 10ft wheelbase seems to have been painless enough but making wagons much longer than that meant there was an increasing number of places where they couldn't be dealt with.

 

[Wheatley]

18 hours ago, doilum said:

In the case of coal, all the infrastructure had evolved around that standardised wagon both at the colliery and consumer end. It took the development of the MGR system with rapid loading bunkers and moving discharge hoppers to provide the clean design sheet needed to change. At the same time coal exports were ending and the Victorian infrastructure became obsolete. No coincidence perhaps that the switch to coal imports and the move to bogie stock happen around the same time?

 

Just to expand on this, there was very little investment in modern loading equipment until the 1974 Plan for Coal, and even then the rapid loading bunkers were largely built at collieries where output from several other pits could be brought to the surface and washed. West Side Washery in Barnsley, for example, was planned to take coal from 16 surrounding pits, either by underground conveyor or by road, but was only taking from 4 or 5 by the time it was completed. Elsewhere loading was still being carried out under Victorian or pre-war screens, some of which could take HAAs and some couldn't. Colliery yards, many on cramped sites, had been laid out around short wheelbase wagons and simply couldn't take anything bigger. Also, until the 1970s there was still a sizeable traffic in house coal to coal yards, for which HAAs and larger were generally not suitable, my local pit (North Gawber) was sending coal out in a mixture of 16 tonners and HAAs (tripped up from the screens half a dozen at a time) depending on the customer.

 

Unloading at CEGB power stations was a bit more organised but there too there was a concentration towards the larger stations on flat sites where unloading loops and stockpiles could be added. 

Edited July 22, 2020 by Wheatley