Take an commuter train to Sosnovy Bor station (Kalishze direction) from Finland's railway station (Finljandsky Vokzal) in St.Petersburg. You can get to Sosnovy Bor (Kalishze) in the space of one and a half hour. There is a bus in the morning and in the evening to Koporje setlement (Kotly direction), which situated 20 km from Sosnovy Bor.
The fortress is 3 km by foot from there. The way to the fortress leads along highway to south-east direction and starts at the crossing highway and railway near to the station.
ps: The local highway is not an european well-equipped highway, but just a surfaced road.