7 Wonders… the GWML
GARETH DENNIS takes us on a journey along a line famous for its features and for the genius of the man who built it, and considers why the Great Western Railway deserves its place as one of RAIL’s Seven Wonders of the Railway
It was built as a racetrack of iron. 118 miles of near-straight alignment carving its way through the English countryside. It was the world’s first high-speed railway, and more than a century later it carried Britain’s first passenger-carrying High Speed Train.
Despite the iconic trains that have operated upon it, this epic piece of infrastructure still manages to make the track the story. As a permanent way engineer, the line as originally built challenges the very core of my beliefs: that system-wide compatibility is the key to a successful railway network. But I still love the Great Western Railway.
To be precise, we are talking about what is known today as the Great Western Main Line (GWML). Not the 1903-built Badminton Line through Bristol Parkway (now the eastern end of the South Wales Main Line), but Brunel’s billiard table via Bath, as it opened between London Paddington and Bristol Temple Meads stations back in 1841.
By the middle of the 1830s, Britain had already witnessed the opening of the world’s first modern railway (the Stockton and Darlington Railway), the world’s first intercity railway (the Liverpool and Manchester Railway), and London’s first terminus (Euston, opened in 1837).
Indeed, Britain was in the grip of ‘railway mania’, with hundreds of schemes proposed by speculative investors each year. Most were short, many were cheaply built, and none had
Whether you are an unwithering fan of Brunel’s or remain more of a sceptic, it is difficult to find another railway that exists in the world with such a clear influence from a single human being.
any real strategic vision in mind. In Bristol, however, events were conspiring to ensure that a railway was built to buck this trend.
The city’s merchants, having neglected the condition of the harbour facilities, feared that they would lose out to Liverpool as Britain’s primary west-facing port, due to the new railways springing up in the North. They wanted a London-bound railway of their own, built to such a high specification that no other railway could compete.
In 1835, they appointed the bold, brash and occasionally barmy civil engineer Isambard Kingdom Brunel as the lead engineer for their newly formed Great Western Railway. Excited by his biggest new project and undeterred by the directionless railway chaos that was frothing up around him, Brunel saw an opportunity to make his mark on the development of the railways. Within a month, he had worked out his preferred route and started crunching the details.
As Brunel said himself: “Looking to the speeds which I contemplated would be adopted on railways and the masses to be moved, it seemed to me that the whole machine was too small for the work to be done, and that it required that the parts should be on a scale more commensurate with the mass and the velocity to be obtained.”
And so… increase its scale he did. Specifically, he widened the distance between the rails (the track gauge) from Stephenson’s 1,435 mm (4ft 8½in) to his own ‘broad’ gauge of 2,140 mm (7ft ¼in), allowing - as he saw it - the larger locomotives required to haul the massive trains the new line would attract.
Yet in its early days, the Great Western Railway was as much a victim of Brunel’s vision as it was later a success. No matter what the possible technical benefits of a bigger gap between the rails would be, Brunel’s use of broad gauge was a phenomenally daft idea from an economic and commercial perspective.
Not only was the capital cost to build the railway double that of similar railways being built at the time, the interface between gauges meant an inability to smoothly operate passenger and freight flows beyond the limits of the Great Western Railway’s infrastructure.
As one of the key emerging functions of Britain’s embryonic railway network, this was a serious shortcoming. The decision to build an inter-city railway using a gauge that was not nationally compatible constrained the economies of Bristol and the South West compared with the rest of Britain, and resulted in population growth being lower alongside the Great Western Railway than along the other London-bound main lines.
Brunel’s choice of route and his decision to minimise the number of stations was also initially problematic. The lack of intermediate railway stations through London’s suburbs limited the sprawl of the city along the Thames Valley, and resulted in a constrained public transport provision even up to the present day. Even Crossrail only has the chance to stop at a few stations in the west of London, compared with the higher frequency of stations in the east.
So much for the Bristol merchants’ aspirations of grandeur? Perhaps not. The connection of South Wales and the Welsh coal mines to the Great Western Railway, once the railway had been converted into standard gauge, allowed it to come into its own. After 1900, Bristol began to thrive.
At this point, Brunel’s foresight into what future railway operations would look like meant that the straight and wide GWML began to be put through its paces. Shortly after the turn of the century, steam expresses in and out of Paddington were averaging over 50mph. By the 1930s, trains travelling on the Great Western were clocking up the fastest average speeds in the world at over 80mph.
To top this all off, the first passengercarrying High Speed Trains (the then-Class 253s) started using the line in the mid- 1970s, helping to transform the fortunes of the railways in Britain after a period of increasingly apparent decline.
Today, thanks to Brunel’s legacy of speed and scale, the Great Western has the capacity to bring 7,000 passengers in as many as 30 trains per hour into London at peak time, while around 450 trains arrive into Paddington station daily (that’s before considering the Underground). It is the gateway from London into most of Wales and the West, and is therefore one of the most important stretches of railway in the country.
Every line in Britain (with a few nerdy exceptions) has an Engineer’s Line Reference (ELR). These were almost always chosen to indicate the name of the line they represent. To give an idea of the place the Great Western occupies within the railway industry - and perhaps the boisterousness of the Western Region divisional civil engineers at the time today’s system was devised - the ELR of the GMWL is MLN, standing simply for ‘Main Line’.
The contemporary over-specification of the original line meant that not only did it intersect many geographical features that required substantial permanent works to overcome, many of its facilities and servicing buildings were of a very high architectural quality - as evidenced by the number that now benefit from listed status. In fact, the line is currently applying to gain UNESCO world heritage status, and this wealth of construction
forms the basis of the bid.
Time to take a journey along the length of this incredible railway that several million people a year experience, and explore some of the defining features that justified RAIL readers selecting it as one of Britain’s Seven Wonders of the Railway.
We’ll start at the zero milepost, and the buffers at Paddington station. Strangely, the station beloved by so many today is not the original terminus of the line. Despite the GWR stopping trains in the area by 1838, the newly opened line operated into a temporary terminus at Bishop’s Bridge - a site that later became the GWR’s goods terminal and is underneath what is now the Paddington Central development site (around the appropriately named Kingdom Street).
In fact, if relations between the Great Western Railway and the London and Birmingham Railway had not turned sour early on in the line’s design, neither the temporary nor final terminus would have come into existence, and Euston may well still have been the terminus of the GWML.
Ignoring the strategic benefits that might have presented for interchanging passengers, it would have denied us an immensely lovely station complex that (despite several substantial reconstructions) remains largely true to Brunel’s original vision.
Opened in 1854, Brunel’s design for Paddington station took cues from the glass spans of Crystal Palace and the Romanesque and Renaissance revivalist stonework of Munich’s Central station ( both now sadly lost), combining them wonderfully to give us the station we recognise now. The 210 metre-long train shed, with its intersecting transepts and the various railway buildings that surround it, offers a unique and valuable entry in the annals of railway architecture.
Anyway, we’ve spotted our platform and have hopped onto a sleek green train. It’s time to go.
Within two miles of setting off, the permissible speed is 100mph for passenger trains. At the four-and-a-half milepost ( barely six minutes after leaving Paddington), the fabled 125mph speed board gives passenger trains the run of the road. It is also at this point that trains going in the other direction start decelerating on their approach to the buffers.
By this point, you’ll have passed Old Oak Common. The depots straddling the main line (Old Oak Common and North Pole) have been the home of several generations of famed traction, not least the High Speed Trains and Eurostar Class 373s, and this legacy continues as they act as the base for Crossrail’s Class 345 Aventras and a maintenance centre for Hitachi’s fleet of Intercity Express-derived units.
The new depots aren’t the only part of the story at this busy bundle of criss-crossing steel. When it opens in the middle of the next decade, Old Oak Common railway station will have a capacity on a par with Waterloo, providing an interchange for as many as 100 million passengers connecting between Crossrail, HS2, London Overground, London Underground, Southern and Great Western services.
Today, thanks to Brunel’s legacy of speed and scale, the Great Western has the capacity to bring 7,000 passengers in as many as 30 trains per hour into London at peak time.
By the time you reach Hanwell, only seven-and-a-half minutes after leaving Paddington, the amount of green outside the window increases as you skip into suburbia. Moments later, you pass over the Brent valley on the 270 metre-long Wharncliffe Viaduct, an edifice built on firsts.
This was Brunel’s first significant bit of structural engineering, the first construction contract let in the building of the line, one of the first structures to be listed (in 1949), and the location of the first commercial electric telegraph (sent in April 1839) and later the first public telegraph line - as well as eventually being one of the first trans-Atlantic cable routes.
If you want to see a vision of the future of main line junctions, you can’t do much better than the now mostly grade-separated Heathrow Airport Junction a few miles further on. The final layout was only completed at the end of 2018, with successive Christmas blockades used to build various over- and under-passes to split long-distance and high-density services from each other - the most obvious is the weathering steel trusses of Stockley Flyover, taking trains out of Heathrow towards Paddington and the Crossrail tunnels.
Eleven minutes and 14½ miles after starting the journey, the GWML punches out from under the M25 and through the stations in and around Slough (which itself is Grade 2-listed).
Perhaps the finest single structure on the entire line is the Grade 1-listed Maidenhead Railway Bridge, and 16 minutes into your journey you’ll cross the Thames upon its two elliptical arched spans.
Despite being built 180 years ago, they remain the flattest ever built in brick. Brunel was famously untrusted when it came to the stability of the structural form, and to satisfy his critics he left the falsework in place on its completion. A storm washed these supports away a year later, and (of course) the bridge stood true.
When its width was doubled in the 1890s,
At its greatest strength, a workforce of 4,000 hacked and hewed at the rock under Box Hill, requiring one tonne of candles and one tonne of explosives per week to illuminate and then blast further into the sandstone chasm.
only fabled civil engineer Sir John Fowler (fresh from designing the Forth Bridge) was trusted with the work, and he thankfully took great care to preserve Brunel’s original aesthetic.
After skirting the side of Sonning village in the impressively deep cutting of the same name, you reach Reading station, 36 miles and 25 minutes after departing the capital. Following the completion of its £ 900 million reconstruction back in 2014, the station acts not only as an intersection of routes linking the Midlands, the West and the South, it is also soon to be Crossrail’s western terminus.
Eight miles later, the line and the Thames alongside it pass through the Goring Gap, a strange geological feature dating from the last Ice Age that forces the line to take its first tighter curves (although the speed is still 125mph). We cross the Thames twice here, over the elegant Gatehampton and Moulsford railway bridges.
At the 53 milepost and 40 minutes after
departure, you’re at Didcot Parkway with the Didcot Railway Centre just to the north. Soon afterwards, at roughly the halfway mark between London and Bristol, the line reduces from four tracks to two. Here, at Steventon, the Great Western Railway briefly (between 1842 and 1843) located its headquarters in a building that remains intact to the north of the old station.
The relief loops between the former Wantage Road and Challow stations provide some additional redundancy in the timetable, but this stretch of the line has a distinctly rural feel to it, and there follows a succession of now-closed railway stations before the line reaches Swindon.
Names such as Uffington, Shrivenham and Stratton Park Halt may have been lost from the railway map, but if they had remained in place the capacity of the line would have to be that much smaller to account for stopping trains holding everything up.
Quite suddenly you leave the countryside behind as you pass under the bypass and enter Swindon, a town that owes much of its existence to the Great Western Railway’s decision to build its locomotive works within its limits.
Not only did its population grow rapidly, thanks to the importance of the works to the operation of the line, Swindon was also the home of several social enterprises that led the way in improving the wellbeing of the working classes. The health provision of the GWR at the Swindon Works was so successful that it was the model upon which the National Health Service would be based. Swindon was also home to various open classes for the betterment of workers, as well as the UK’s first lending library.
A little over an hour after leaving London, the South Wales Main Line (on its straight line towards Bristol Parkway and the Severn Tunnel) diverges from the original Great Western Railway at Wootton Bassett Junction, taking with it the energised overhead wires (more about that later).
As we sail through Chippenham, 94 miles from Paddington, we are still at 125mph - even though the line is a little curvier than it has been previously. Just short of the 99 milepost, the line reaches its steepest gradient of 1-in100, and we start the descent towards the infamous Box Tunnel.
Owing to the complex geological composition and proposed gradient of the line through the tunnel, Brunel had been repeatedly warned that its construction would be impossible. But that didn’t stop him.
At nearly 3km (1.8 miles) in length, it was the longest railway tunnel at the time of its opening (in the UK at least - it was surpassed four years later by the first Woodhead Tunnel at 4.8km - three miles). And the material eventually excavated in its construction (if piled up) would have been nearly three times the size of Buckingham Palace. More than 30 million local Chippenham bricks were used to line the western end of the tunnel, enough to build 4,000 houses.
At its greatest strength, a workforce of 4,000 hacked and hewed at the rock under Box Hill, requiring one tonne of candles and one tonne of explosives per week to illuminate and then blast further into the sandstone chasm. The construction was not without loss, however, with an estimated 100 navvies losing their lives, mostly in flooding and blasting.
Having emerged from the western portal of Box Tunnel, almost exactly 101 miles from the buffers at Paddington, we find ourselves entering hillier terrain and contending with a curvier alignment. At the 101.5 milepost, and at the eastern portal of Middle Hill Tunnel, we reach our first permanent speed restriction of 100mph outside of London (ignoring a brief drop through Reading station).
The gradient levels off again as we come out of this short tunnel, and the train starts slowing on the approach to Bath Spa station
and the UNESCO World Heritage site of the City of Bath.
Brunel’s approach to the design of the GWML through Bath is nothing short of showing off. In 2012, Alan Baxter & Associates made its assessment of the historical and cultural merit of the structures along the line, in advance of electrification, and it is difficult to find a better description of his extravagance: “The engineering of the GWML through Sydney Gardens is a piece of deliberate railway theatre by Brunel without parallel. This utterly unique section of the line integrates line of route, landscape, retaining walls and bridges into a single engineering and design tour de
force, in which every element responds to the picturesque Georgian planning of the Bath World Heritage Site.”
The final section of the GWML between Bath and Bristol includes a great many more tunnels and structures, and the permissible speed doesn’t climb above 100mph.
The last of the great structures before we reach the centre of Bristol is the Tudor gothic (and Grade 1-listed) Avon Bridge in Brislington, now flanked by two newer and rather less attractive spans. The erection of this bridge gives us a chance to glimpse Brunel’s darker side - as the Bristol to Wootton Bassett section of the line became more delayed, the contractor who was originally intended to undertake the work was cornered by the Great Western Railway’s engineer-in-chief and ruined, when he tried to suggest that poor quality materials provided by the GWR had contributed to slow progress.
A little over 118 miles from the buffer stops in Paddington, we reach the grand Temple Meads station and the terminus of the original GWML.
Brunel’s Bristol terminus was built in a much timelier manner than his London terminus (opening in 1841), and thanks to later reconstructions has remained largely distinct from the expanded and now-familiar curved platforms and train shed. The Tudor-styled offices and former terminal platforms are located to the west of the present-day station building and are now used for events, having handled their last trains in 1965 and been lovingly restored more recently.
Temple Meads station has gone through several substantial reconstructions, with new platforms being added in the 1850s, significant changes being made in the 1870s, and then a doubling in its size again in the inter-war period to broadly give us the station we recognise today, complete with its grand clock tower.
The journey we’ve just taken is the same one that hundreds of millions of others have taken in the 180 years of its operation, but it has
been greatly improved thanks to successive upgrades and changes in rolling stock.
As you step out into Bristol, less than two hours after leaving the capital, think of the gargantuan effort not only to build the GWML, but also to maintain and upgrade it for the 21st century.
Clearly the most radical change to the railway is the most recent upgrade - the Great Western Electrification Programme is the largest investment in the line since its construction. By permitting electric-only trains with better performance and more seats, the capacity of the line is being significantly boosted, with thousands of extra seats a day (an extra 30% at peak time).
However, it hasn’t exactly been plain sailing since the project began in 2012. The resilience of the original GWML has caused at least some of the challenges in upgrading it for the 21st century, with the limited work done by British Rail to run its 125mph-capable High Speed Trains meaning that there was only a very cursory understanding of the existing assets. This meant a lot of ‘unknown unknowns’, which hasn’t made life easy for the designers or installation teams.
Nevertheless, and given that the wires to Bristol Parkway were energised in December 2018, it is worth taking a step back from the challenges and thinking about the scale of this achievement. Some 700 single-track kilometres of line (435 miles) have been electrified over the past five years, which isn’t bad going considering that electrification of the East Coast Main Line took 15 years for 2,250 single-track kilometres (a similar rate), yet there has been a near-vacuum of wiring work since the end of that project.
More than 7,400 masts, 4,800 booms and over 750 wire runs now provide electric power to a new fleet of electro-diesel ( bi-mode) express trains - a compromise when
In 1835, they appointed the bold, brash and occasionally barmy civil engineer Isambard Kingdom Brunel as the lead engineer for their newly formed Great Western Railway. Excited by his biggest new project and undeterred by the directionless railway chaos that was frothing up around him, Brunel saw an opportunity to make his mark on the development of the railways.
compared with fully electric units, but a useful temporary innovation looking forwards to the incremental electrification of the rest of the UK’s main line network.
There’s more work to be done, of course. The branches connecting onto the GWML as well as the route through Bath and into Temple Meads remain unelectrified, despite significant disruptive works having already been completed in preparation. Furthermore, complete resignalling of the line with full ETCS and ERTMS (European in-cab signalling and train control) is due for completion before the end of the next decade, eking yet more capacity out of the line by squeezing trains even more closely together.
And what of the gauge question? Was Brunel right after all? Should we have adopted a wider distance between the running rails?
Actually, neither Stephenson’s standardgauge nor Brunel’s broad-gauge are the optimum arrangement from a mechanical perspective. If we could start from fresh, the optimum track gauge is around the 1,600 mm mark (it turns out the Irish got this right) but perhaps that’s a discussion for another day…
Whether you are an unwithering fan of Brunel’s or remain more of a sceptic, it is difficult to find another railway that exists in the world with such a clear influence from a single human being. Other railways were undoubtedly created more economically, and other railway engineers may well have more railway miles to their name, but the mark that the Great Western Railway made on the development of the modern railway will never be forgotten.