This type of issue has been around for a long time. The initial Long Beach race had similar problem. The cars have so much down force, they "picked up" the man hole cover, which weighs about 60 pounds. Fortunately Long Beach uses a cast iron ring and they ended up welding the cover to the opening ring. The issue in Las Vegas is that they use a much less expensive concrete opening ring. So welding the cover isn't an option. They do a lot of good things in LV but as it turns out manhole covers is not one of them.