In hindsight, we could probably come up with a number of plans but the problem with all of them would be in execution. Even military commanders have difficulty executing a mass troop movement under stressful conditions. In a city like Houston, it would be virtually impossible to stage a successful evacuation of a diverse civilian population, even if it was limited to designated neighborhoods or facilities. Human beings are just not good at following orders.
I think it can be agreed that property damage would be the same with or without an evacuation. In the last partial evacuation, many people spent a miserable 24 to 36 hours sitting on the highways getting out and another day getting back and there was over 100 lives lost. As insensitive as it may sound, the only real measure is the body count and so far, the shelter in place strategy has a loss of 6. Either way, the person making the decision is going to be criticized. That just goes with job
There are tried and true methods of moving large numbers of people away from threatened coastal areas that I don’t see being implemented such as “contraflow.” That would be reversing the direction of one side of a multilane highway in order to double the vehicle capacity outbound and inland away from the threat. This has been done in Miami/Dade and numerous other areas including the Carolinas. If set up, drilled and agreed upon well beforehand, with designated sections evacuated one by one in priority of risk exposure, it absolutely does not have to be a death trap of a parking lot going on for hundreds of miles. Yes Houston is a huge metro, but being somewhat inland the entire city would not need to be evacuated, just the known flood risks, the very low-lying areas, alongside rivers, creeks and bayous. I’m surprised such a preparedness step has not been taken there. This was known to be a potentially historic storm from a standpoint of rain accumulation well before landfall. It was on a weekend, so commuter traffic would not have been a major issue. There’s no reason for there not to be such a plan for the entire coastal region. Make it optional if need be to placate the Texan independent streak, but those who choose to remain in the face of an implemented evacuation should have to take the morbid steps that sheriffs and police have been telling evac refuseniks for decades, mark your social security number on your arm with an indelible marker for identification, police and emergency personnel very well will be unable to reach you in the event that you get into trouble.