Possibly Unique 1910 18 Size, Hampden Electric Railway Serial No. 2640034 [not part of my collection, mores the pity] 17 Jewel, Model 3,  ON3P-A. [Check up-date; Thurs. 12/22/2016. This is now a part of my collection].

Single Sunk, Arabic Dial, with Spade "Railway" Hands.

Movement is like the 17 Jewel Dueber Grand but is signed "Electric Railway". Otherwise a standard Open Face, Model 3, Pendulum Set, Adjusted, 17 Jewel, Hampden it's the only example I have ever come across. 

The Dueber-Hampden Watch Co. did make a 16 size "Electric Railway Standard" [previously documented here] but this 18 size Model is not listed anywhere & seems to be a "one-off" trial model. The 16 size Electric Railway Standard watches are quite rare so they must not have found much of a market & were discontinued around this time, which most like figured in the reason the 18 size Electric Railway was never put into production.