Thanks for the tip! It seems it will go up the hill:
According to http://www.dcnrhs.org/trips/FFE/TTEX.htm
"During our train excursion to the 41st Catoctin Colorfest, you will see the beautiful fall colors while traveling through scenic Maryland farm country as we climb the foothills of the Catoctin Mountains to Thurmont. There is an option for an additional side-trip up the dramatic Catoctin Mountains west of Thurmont for an additional $10 charge."
I assume this means to Highfield and back down.
Although, it could be just a bus side-trip
Quoting some more FYI:
"The "FFE" begins with a morning departure from Washington Union Station and a run up to Baltimore on CSXT's (ex- B&O) Capital Subdivision (Marc's Camden Line), making stops at College Park and Dorsey en route.
Upon our arrival in Baltimore, the "FFE" will work its way to a connection with CSXT' s Hanover Subdivision (ex - Western Maryland Railway). We will then head west from the connection up to Emory Grove, Md, the interchange point with Maryland-Midland Railway's east-west main line. The "FFE" will be taking this Maryland Midland trackage all the way from Emory Grove west to the Colorfest in Thurmont.
Of special interest is on this leg of the trip is operation over the segment between Emory Grove and Westminster, which was severed by hurricane damage in the early '70's and returned to service in the late '80's. It has seen scant passenger train operations since its return to service.
Over the rest of our way west on the Maryland Midland, we will be passing through Union Bridge, and eventually arriving at our temporary station on Apple Church Road in Thurmont."
They don't say anything more about the side trip up from Thurmont, either bus or rail.