If you newbies are ever in this situation , just call for help or slowly back up.

Driver Fails at Low Bridge U-Turn - USA Truck

Being a driver I can say this. Don't try the u-turn. Back it up nice and slow if you have no traffic or someone willing to help. If you don't have that or are unsure, call the police. They can help you out in a timely manner with no damage to the truck. Plus as long as you haven't violated any weight retrictions, you usually don't get a ticket, you keep your job and you don't have this embarrassing video on youtube. 

I am fortunate that I have not had this exact situation happen to me, but I have come to unmarked dead ends on small county roads with ditches on either side. All I did was throw on my 4 ways, back up slowly and when a car came up behind me I stopped until they went around me. Continued this until I found a safe place to pull into that I could get turned around in safely and legally. No damage to the truck.