horseshoe curve

plural horseshoe curves

1. A curve in the shape of a horseshoe, often on a railway, where hairpin bends cannot be used.

   The viaduct has nine steel spans on a 16-chain (328-metre) curve and is one of two significant structures on the celebrated Horseshoe Curve.

   2021 December 15, Robin Leleux, “Awards honour the best restoration projects: The Costain Structures Award: Auch Viaduct”, in RAIL, number 946, page 57

   2 more examples

   It only remains to notice briefly the branch from Whitland to Cardigan, which for a few miles pursues its tortuous and picturesque course along the valley of the Taf, thence rising by very severe gradients to Crymmych Arms, near to which station is a striking horse-shoe curve.

   1939 September, T. R. Perkins, “The G.W.R in West Wales”, in Railway Magazine, page 202

   This route was constructed in 1883 and involves a horseshoe curve, two tunnels, ruling grades of 3.76 per cent southbound and 3.91 per cent northbound (with patches up to 4.8 per cent), and severe curvature.

   1959, David P. Morgan, editor, Steam's Finest Hour, Kalmbach Publishing Co., pages 113, referring to the line between Mexico City and Toluca