Right now, Lavon in a tough spot regarding commuting in and out of the area. A few years ago, I was on my way home, when there was a serious accident and they shut down 78. We sat on the highway for almost two hours. Like you pointed out, your only options are to backtrack, make your way to Rockwall and come up 205, or backtrack to 75 in Plano and come over via 380. Either route, your taking the really LONG way home. I opted to wait it out. As much water as they let out of the damn at times, I'm surprised that bridge hasn't washed away :-)