According to the Font Bureau’s promotional copy, Titling Gothic was inspired by Railroad Gothic.
To me it feels a more like old standbys Univers and Helvetica, but with the panache of custom-lettered advertising headlines from the fifties and sixties. The immense range of styles offered (seven weights and seven widths) makes this a really flexible sans serif family. The only down side: no italics.
The varietals are out of control useful. A wonderfully expansive creation.