[s_forbes]

Given that the robot was able to drive up the bridge (I'm assuming from the other photos that it made it up under it's own power), there must be enough weight over the drive wheels for it to power itself up, in which case grappling the lip is not necessary to stay on the bridge. I highly doubt you would be able to drive a robot up the bridge if it relies on clamping force on the lip to keep it from falling off. I'm curious as to how the friction from the portion of the robot touching the lip did not inhibit it from driving up though.

Doesn't look "clearly illegal" to me.

Congrats to 3534 for creating and carrying out this design! Out of the box approaches are risky but oh so cool.