If you go far enough north in Sweden you’ll strike iron. Specifically, you’ll come across iron mines in Kiruna, Svappavaara and Malmberget. They’re operated by a company called LKAB who obviously need to transport the iron ore to somewhere it can be used. They choose to do this by rail, mainly because they hadn’t much choice back in the late 19th century when the mines were opened. Lines were built south east to Luleå on the Baltic and later westwards to Narvik in Norway, a place chosen because despite being so far north it’s ice free year round. Sweden has lots of cheap hydro electricity and so the line was electrified in stages with the final section being completed in 1922. Yes, I was a little surprised too that heavy rail was being electrified a hundred years ago.

Over the years the rolling stock has become more ambitious and LKAB have progressed to 100 tonne wagons and a fleet of Bombardier Iore locomotives. It’s the locos that we’re going to be investigating. They’re composed of a pair of semi-permanently coupled single ended units of 5.4MW or about 7,200 bhp each, a high figure by diesel standards but nothing unusual by electric ones. Taken as a pair then each combination has 10.8MW or 14,400 bhp available with more on hand for short bursts which makes them amongst the most powerful locos in the world.

Yes, big snow ploughs. They work in the Arctic.

They’re used to tow 68 wagons at a time with a laden weight of about 8,600 tonnes. The mines are in the mountains, the two termini are, in the nature of ports, at sea level so the laden trains go downhill. Therein lies an opportunity. The wagons use conventional friction braking but the locos also have electric retardation which uses the traction motors to produce electricity. Just like a Prius then but on a rather larger scale. Normally this is wasted by using it to heat a resistor on the loco roof, but not in environmentally conscious Sweden and Norway. They choose to recover the electricity and send it back into the grid. As the trains are descending full and coming back empty the energy recovered during the steepest part of descent, from the Norwegian border to Narvik, is sufficient to get the train back to the border again. So, free travel, albeit only for a Norwegian part of the journey.