Me and a couple of my friends were playing conquest last night on the highway map (cant remember the full name) anyway I got sniped by someone, and in the kill cam it showed him on a road with railing behind him. So I changed to recon and started using the MAV to try and spot him for my team. After checking the usual places and not finding him I thought he'd moved, but my friend got sniped by the same person in the same place.
Anyway it turned out him and three of his mates were actually on the highway that runs through the game and you shouldnt be able to get too.
It turns out its actually quite easy to get up there (not going to say how, but Youtube it and you'll see) and the person who made the video for Youtube actually tries to justify it by saying DICE hasnt fixed it, so they obviously want people to get up there.