Although they pretty well served their purpose and nobody complained about them, these ramps should be considered the absolute minimum acceptable.
Extremely easy and cheap to build, they end up being too light for good racing. Because the front of the ramp is so light (which is good only for transportation) they are so light-weight that they will lift when you pull off from the ramp using your full power.
It can be solved by people standing on the bottom pieces of the ramp (one on each side) to hold it in place, but it's not ideal.
It wasn't a problem here, but it is important that the running surface is solid enough. I remember racing on a ramp where the surface ultimately cracked and a pair of wheels got stuck in the hole. The skater ended up free-flying... I dream night-mares about this every now and then. Please rampbuilders, make sure the surface is solid and strong.
Notice the important board stopper at the end of the ramp.