The Tunkhannock Viaduct sees anywhere from 10-12 trains per day on average, however there can be as many as 15 per day. Alot has changed symbol/operation wise since the train chart posted above was created:
Heres a simplified but NEW list of train symbols/average times over the bridge.
CP 158 (South)Intermodal/Freight Tu, Th, Su - Over Nicholson b/w 18:30 and 20:00
CP 159 (North) Intermodal/Freight Tu, Thu, Sa - Over Nicholson b/w 06:00 and 09:00 (Good bet for an After Sunrise Northbound over the Bridge)
CP 256 (South)Intermodal/Auto/Freight/Garbage -Daily - " " b/w 15:30 and 18:30 (Good bet for Mid afternoon Southbound)
CP 257 (North)Intermdoal/Freight/Garbage - Daily - " " b/w 06:00 and 10:00 (Usually a good bet for an A.M. Northbound)
CP 458 (South)Freight/Autos - Daily (NS power) - " " b/w 05:30 and 09:00 (Usuall good bet for an A.M. southbound)
CP 459 (North)Freight - Daily (NS power) - " " b/w 19:30 and 23:00
CP 550 (South) Intermodal/Freight - Su-Fr - " " b/w 20:00-22:30
CP 551 (North) Intermodal/Freight - Su-Fr - " " b/w 02:00-05:00
CP 552 (South) Freight - Wed, Fri - b/w 07:30 and 10:00 (Good bet for A.M. southbound)
CP 553 (North) Freight - Th, Sa- b/w 09:30 and 13:00 (Good for A.M./Early P.M. Northbound) "Sometimes lifts cars out of Taylor Yd/Taylor intermodal"
NS 930 (South) Freight/Autos - Daily - " " Train can run any time of day.
NS 931 (North) Freight - Daily - " " b/w 21:00 and 01:00
NS 932 (North) Freight/Autos - Daily - b/w 23:00-04:00
NS 933 (South) Freight/Autos - Daily - b/w 23:00-04:00
Other symbols commonly heard/seen
NS 9-930 (NS southbound Non-Scheduled Extra ie. coal, rock, rail, etc.) - Runs as needed
NS 9-931 ( NS northbound Non-Scheduled Extra ie. coal, rock, rail, etc.) - Runs as needed
NS 2-930 (NS soutbound Second Section of NS 930) - Runs 2-3 times per week with Autos/Freight from Buffalo, NY
NS 2-933 (NS soutbound Second Section of NS 933) - Runs as needed.
As listed above, in the Early A.M. hours, you will likely see 458 southbound and 257 and 159 northbound. Although a late running 933, 932 or 930 are a possibility as well. Extra's run at anytime, and it is possible you may see one of those as well. If you stick around until late morning you should also catch the 553 heading north and mid afternoon/evening the 256 heading south.
I hope this helps and good luck!
As for the Starucca Viaduct, it a beautiful sight to see (Although not nearly as nice as Tunkhannock Creek IMO). But I wouldn't waste your time waiting for a train in daylight (cause your not gonna see one). The line sees 6 trains a week and all run at night on that part of the line. Things may change soon but as of now its worthless for train watching!
Also if you wanna learn more about the CP Sunbury Sub, feel free to check out and join my yahoo group "cprsunburysub"!