You should now be on a train rolling out of Cardiff. Welcome aboard!
The Merthyr Line roughly follows the waters of River Taff. If you haven’t seen it already, it will be coming into view soon. Since the glacial period, the river and its tributaries have given the Mid Glamorgan Valleys their shape over millions of years of storms coming in from the Atlantic; dumping hefty rains against hills and loosening the dirt and rocks with attrition, abrasion and general splashing, working its way down to the Severn Estuary at a rate of many tonnes of sediment every year.
But in the last couple of centuries, the river has had a bit of help. As soon as humans figured out how to do it, iron and coal have followed the Taff’s course from the mines up in the hills, down roads, canals, tramways, and eventually railways that have been crammed into the Taff Valleys, and eventually to trains and ships that took it on further to feed the machinery of the industrialising world.
This process not only further shaped the Mid Glamorgan Valleys into what we see today, but it shaped the world into a new industrial form. It was here, along this very route, that the world first stepped into the anthropocene – the current geological age in which human activity has been the dominant influence on the environment – about 270-odd years ago, around the time the first modern mines and ironworks were built in Merthyr Tydfil.
In the narrowing valley ahead, you don’t have to stray far from the current railway line before you come across previous versions of the ways the new industrialists found to get the iron and coal from the hills to Cardiff and on to the sea.
The first version was a basic tramway of horse-hauled carts moving along L-shaped plates, which was built around the time of the first ironworks in the 1760s, almost as an extension of the rails that came out of the mines.
Then came the mighty, man-made Glamorganshire Canal. It ran from the Cyfarthfa ironworks through 52 locks, over the Taff at Abercynon, and all the way to the docks in Cardiff. It prospered: by the end of the 1830s, 200,000 tonnes were being transported down it every year. But by the end of the century, this would need to increase almost 100-fold to keep up with the sheer volume of materials being mined.
So then came the region’s first railway service, the Taff Vale Railway. The tracks that were laid back in the 1840s followed more or less the same route you’re on today. There were even more railways built – criss crossing between and across valleys with tunnels and bridges heading to other ports such as Penarth, Newport and Swansea – to keep up with the ever-growing volumes, now running into the millions of tonnes per year.
The whole system of extraction reached its zenith just before the first world war. Over 50 million tonnes of coal was being mined in Wales every year by around 250,000 men.
Then oil grew in importance globally, coal was found overseas, mining unions grew in power. Eventually coal mining and railways were nationalised and rationalised. Once a throbbing central artery of the global economy, the River Taff and its man-made variants are now quieter.
Some of the original tramways and canals were largely paved over to make roads including the A470, and what is left has been incorporated into the Taff Trail walking and cycling route. The railway is largely for people like you.
There are actually two lines out of Cardiff Central which will converge at Radyr. If you’re on the Eastern route, you will soon come over the Afon Taff Viaduct, the first of the bridges designed by Isambard Kingdom Brunel – a man who probably needs no introduction, and who I’d struggle to summarise in this format.
If you’re on the Western route, you may get a glimpse of this viaduct briefly across the Taff on the right hand side. This Western route was laid precisely because the Afon Taff Viaduct and the docks that were at Cardiff Central couldn’t deal the growing traffic. Eventually, the tracks from Cardiff to Pontypridd were quadrupled, and the Avon Taff viaduct was widened (twice) since its original was built in 1840.