^He drilled a hole up through the bottom of the wood and then through the pvc too, and put nuts and bolts in through those holes
Real nice looking rail. Even if you don't think you need them you would benefit from putting in diagnol supports. The rail is new and stable now but riding all winter puts alot of stress on those joints over time. Also you did a real good job connecting the rails to the wood. You may want to consider adding two more nuts and bolts horizontaly connecting the two pvc pipes together. that way if there is stress placed in between the two pipes (like a ski slides inbetween on a switch up) its less likely for the pipes to break or split off to the left or right. Just some suggestions either way it looks fun nice job