Interesting website here with lots of information, photos and topo maps: http://www.wmwestsub.com/main.htm
I haven't delved deep into Western Maryland's history, but their mainline towards Pittsburgh seems to be heavily engineered, for double track operation even.
The big Salisbury Viaduct has two track columns, but only a single track line of bridges atop: http://www.wmwestsub.com/connellsvillesub/salisburyviaduct.htm
The Keystone Viaduct is a double track through truss bridge with only one track installed: http://www.wmwestsub.com/connellsvillesub/keystoneviaduct.htm
What if Norfolk Southern acquired WM, would there still be two main railway lines over Sand Patch?