Brunel originally built the Great Western Railway to his unique broad gauge of 7 feet between the rails as he thought this would give extra speed and comfort.
But as the railway network expanded the Great Western had increasing problems with transshipping goods onto the standard gauge, or 'narrow gauge' as they called it, of the other railways and its broad gauge was finally abandoned in 1892.
However, at Didcot Railway Centre the Great Western Society has recreated a section of broad gauge railway using materials recovered from a disused railway near Burlescombe in Devon together with the relocated Didcot Transfer Shed built in the 1850s to transship goods between broad and standard gauge trains.
Much of the recreated railway is laid as mixed gauge track, capable of carrying both broad and standard gauge trains. A quick look at the resultant complexity of pointwork shows the considerable increase in material and maintenance costs that such a layout involves.
In addition to the track and the Transfer Shed there are many other features reminiscent of the Great Western Railway's ‘broad gauge’ era in this part of the centre - Look out for the characteristic disc and crossbar signal and the Railway Policeman’s Hut.
‘Fire Fly’ is a faithful replica of the original ‘Firefly’ locomotive designed by Daniel Gooch in 1840 to run on Brunel’s broad gauge Great Western Railway between Bristol and London.
The replica was conceived by the members of the Firefly Trust and they have assembled it at Didcot Railway Centre where it now operates.
‘Fire Fly’ operates the broad gauge railway together with replicas of a third class coach, open to the elements, and a second class coach, which at least has a roof! Both were originally built by the National Railway Museum for the 150th anniversary of the Great Western Railway in 1985 and have been extensively rebuilt by the Great Western Society.
The original ‘Firefly’ was the first locomotive designed by Daniel Gooch, first locomotive superintendent of the Great Western Railway, and was one of a class of sixty two; built in May 1840 it ran until 1870. Gooch took advantage of the broad gauge; his locomotives travelled at much faster speeds than those made previously. In all he designed 340 locomotives.
The Firefly class handled the principal trains from London to Bristol when they were new and were capable of hauling trains weighing 80 tons at speeds up to 60 miles per hour; one of the class hauled the first royal train, taking Queen Victoria from Slough to London, in 1842. The wheel arrangement is 2-2-2, the single driving wheel being 7 feet diameter, and the weight 24 tons 4 cwt.
The Firefly Trust’s achievements were recognised by the Heritage Railway Association by the award of the 2005 John Coiley Memorial Prize for locomotives. In 2013 the locomotive was given to the Great Western Society who are now its custodians.
Adjacent to the broad gauge running line is a display on Brunel's ill-fated attempt at ‘atmospheric’ propulsion. The three 22” diameter cast iron pipes are a relic of I K Brunel’s flirtation with atmospheric traction on the South Devon Railway. The tubes were discovered, by the Great Western Society, being used for drainage at Goodrington in Devon and are displayed on broad gauge baulk road at the 1 in 36 gradient of Dainton Bank, the steepest part of the line for which they were intended.
The South Devon Railway was persuaded by Brunel to adopt Clegg & Samuda’s system of atmospheric traction. This consisted of stationary pumping engines creating a partial vacuum in large slotted cast iron pipes laid between the rails. The pipe was sealed by airtight valves at each end and a metal strip hinged by leather along the length of the slot. The partial vacuum allowed a piston attached to a carriage to be propelled by the greater pressure of the atmosphere behind. This system was intended to be capable of operating trains on much steeper gradients and sharper curves than locomotives could manage.
The largely flat section of the Railway between Exeter and Newton (Abbot), including the scenic seawall section, was duly built with 15” pipes for atmospheric operation, experimental services beginning in September 1847 and full atmospheric operation commencing in February 1848.
The 22” pipes, such as those on display, were intended for the steeply graded section between Newton and Totnes where the larger diameter was needed for greater tractive effort. However as this section was being built the system’s failings were becoming evident. The leather hinges were inadequate and air leaked into the pipes overworking the undersized pumps. The 1848 accounts show that atmospheric working cost 3s1d (15.5p) a mile compared to 1s4d (7p) for locomotive working.
Atmospheric working between Exeter and Newton was discontinued from 10 September 1848 (after only 7 months). The Newton to Totnes section was never opened for atmospheric traction, though an engine house was built at Dainton, and pipes were laid from Newton as far as Dart Bridge in Totnes.
The steep grades and sharp curves of this part of the line have remained, as a legacy of Brunel’s ‘Atmospheric Caper’, to provide a challenge to Great Western locomotives and their successors as they struggle to lift their heavy trains over the South Devon banks.
This is displayed near to the Railway Centre entrance. It was originally installed within Devonport Dockyard and is thought to have been manufactured for the Cornwall Railway circa 1868 when they were contracted to carry out some work at the dockyard involving laying a short loop on the east side of the North Basin in North Yard, to include a 13 feet diameter Heanett & Spinks turntable. It may be that this is the example preserved here, though by the time it was recognized as historically important (in 1992) it was located on the east side of No. 3 basin in South Yard, apparently having been moved there at some time after the Second World War.
There had been a scheme to preserve the turntable at Devonport as part of a proposed museum, but with this proving impractical the turntable was purchased by the Bristol Group of the Great Western Society in 2008.
These small turntables are often known as ‘wagon turntables’, though they are easily traversed by a small locomotive, and can even be used to turn one provided the wheelbase is short enough. Unlike the larger turntables which were used to turn locomotives at the end of their journey so that they were facing in the correct direction for their return, these turntables were mainly used to provide access to awkward locations. In dock areas this allowed access for single wagons into buildings and onto jetties and quays, and they were also much used inside goods warehouses and industrial premises. However they were also heavily used at major stations in the early days of railways, where they would allow for individual coaches and wagons carrying the road carriages of the wealthy to be easily attached to trains.
Such turntables were operated by manpower, generally by the simple mechanism of pushing against whatever it was standing on the turntable ready to be turned. In many cases the spur lines running from these turntables were quite short and any movement of vehicles to and from the turntables would also be by manual operation, although sometimes horses, or even systems of ropes and powered capstans might be used on larger or more heavily used installations.