Cant walk over bridge


Im currently learning Blender and Unreal Engine 4, and am trying to see if I can actually make a game. Im working on the landscape, and have made a bridge in Blender and imported into UE4. But Im having just one problem; I cant walk over the bridge. I can walk up to it, but when I try to walk over, its like its a wall im bumping into. Anyone know what I did wrong?

I modeled the bridge after a youtube-video where the youtuber model things to 3d-print. I would love to know what I did wrong… :S