Everyone: I will second CHTT and mention that the definition should be attractions that
are only accessible by way of either regularly scheduled passenger or tourist trains.
In the original post Horseshoe Curve is accessible by road from Altoona or Gallitzin, PA.
The railfan park at the Curve may either be closed or offer limited access currently with
the funicular between the parking and viewing areas closed (for maintenance?) now.
Starrucca Viaduct in Lanesboro, PA has no regular scheduled passenger or tourist train
service and is accessible by local PA state roads (92, 171) in that area (Susquehanna Co.)
I will add Tunkhannock Viaduct in Nicholson, PA (Wyoming Co.) is in this same category
with the rail route having no passenger or tourist train service. Road access is provided
by either US Route 11 or PA 92 to the area.
In comparison Moodna Viaduct in Orange County, NY has regular scheduled passenger
train service on Metro-North's Port Jervis Line (operated by NJT). The nearest station is
Salisbury Mills-Cornwall which is just west of Moodna Viaduct. There are local roads in
the area that pass under the Viaduct.
The definition should be attractions that are either only accessible by train or places
that are best seen on board a train for those having at least some road access.
EXPRESS TRAIN TO NEW YORK PENN STATION-NO JAMAICA ON THIS TRAIN-PLEASE STAND CLEAR OF THE CLOSING TRAIN DOORS