N&W class Y6a #2156 sits by N&W class A #1218 awaiting a call to service. No. 2156 is a 2-8-8-2 and the sole survivor of the railroad's Y5, Y6, Y6a, and Y6b classes. This locomotive was among the hardest-pulling steam locomotives ever built with a tractive force greater then that of the larger 2-6-6-4 class A's, such as N&W's #1218 seen to the right, and even Union Pacific's Big Boys (166,000 lbf vs 114,000 lbf, and 135,375 lbf respectively). Both engines featured above were built by the railroad's Roanoke shops, #2156 in 1942 and #1218, a year later in 1943.