Could also consider reinforcing it with a formed additional piece of plastic to wrap around the outside and cemented in place.
Since you say the bottom of the ramp is very thin, that would mean this was likely done with a "female" mold.....other words, upright. The upper turn would also be very thin at the bottom as the plastic gets pulled down into the mold. The need for the female mold would be due to how narrow the turn to the left is and the resultant narrow gap between them. That narrow space between the upper left portions of the ramp are most likely why this was done in a female mold to avoid the plastic "webbing" which is what would happen on a male mold....tough to pull plastic down into an area like that without some assistance. I think I would lean toward a male mold and plug assist that area. Doing this on a male mold might resolve most of these issues.