horseshoe curve

horseshoe curve (plural horseshoe curves)

1. a curve in the shape of a horseshoe, often on a railway, where hairpin bends can't be used.
   • 1959, Steam's Finest Hour, edited by David P. Morgan, Kalmbach Publishing Co., referring to the line between Mexico City and Toluca:

     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.

• hairpin bend