From a series written for Radio National’s Blueprint for Living. The cog radio first aired on 9th September 2023. You can listen to the audio here.

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In 1811, British engineer John Blenkinsop couldn’t believe that a steam locomotive could haul heavy coal wagons without slipping on the metal rails. So he designed the Salamanca, which had a cog wheel on the side that engaged with teeth attached to one of the rails. And it worked beautifully, moving coal the short distance down the hill from the Middleton mine to the centre of Leeds in Yorkshire. But as railways were established around the country, it soon became clear that locomotives didn’t need any additional help to move forward: the weight of the train was enough to keep the wheels engaged.

Blenkinsop’s idea of assisted traction was a good one, though. Especially when people started thinking about laying railways in the mountains. Using a cog system enabled trains to move more directly up steeper inclines, incurring less cost than a conventional train which would require more track. The idea inspired the possibilities of bringing materials from mines or quarries in hilly areas and yet, it was the budding tourist industry that really pushed things forward. By the middle of the nineteenth century, the new middle classes were eager for the kind of adventures previously only available to the wealthy. The Americans were the first to exploit this, with the Washington Mountain Railway in New Hampshire taking fare-paying passengers up a steep track to a hotel at the top of the mountain in 1869. This train used a system designed by Sylvester Marsh with a third rail laid between the outer rails. It had rungs rather like a ladder and the cog wheel on the underside of the locomotive had deep teeth that engaged with the rungs, helping propel the whole train forward without any slippage. It runs still, just as designed.

The Swiss were captivated and Niklaus Riggenbach devised a similar system for their first cog railway in 1871. It climbed Rigi mountain, overlooking Lake Lucerne, quickly making it a must-see destination for British tourists on trips organised by the first mass tourist operator, Thomas Cook. Variations on the rack theme were devised according to the demands of particular terrain. Like that designed in 1889 by Eduard Locher which had teeth along each side of the central rail with which twin cogs, set horizontally, would engage. It enabled the train to ascend what remains the steepest cog railway in the world, Mount Pilatus, across the lake from Rigi, with gradients reaching a stomach-fluttering 48%. By then, though, most cog railways had adopted a system designed by Swiss inventor Carl Abt, using a central rail with a single row of teeth along its top. The Abt system was tweaked, though, for a new railway that climbed to a saddle between the Eiger and the Jungfrau mountains, known as the Jungfraujoch. This railway was a dazzling feat of engineering design, with the cog railway running in tunnels hewn deep into the Eiger mountain itself, with stopping-off points along the way, and windows giving views through the famed North Face. Here, the Abt cog system was given an additional safety measure devised by Emil Strub, adding safety jaws that gripped the underside of the central toothed rail, rather like the brakes on a bicycle wheel. Cog railways remain relevant throughout the world. While Switzerland is their spiritual home, with the greatest number of cog railways still in daily use, they’re vital infrastructure in other places, from India’s Nilgiri mountains to the Skitube in Australia’s Snowy Mountains that opened in 1987. While John Blenkinsop might have over-engineered the answer to a question only he thought to ask, he pioneered an idea that echoes still across the peaks of the world today, adding charm and convenience to the steepest ascents.