How hard would it have been to announce that evacuation of known highly flood-prone areas was strongly advisable and could very likely become mandatory, with a plan quickly devised section by section in Houston, with those furthest away from interstates heading out of the area of potential flooding getting first priority? I’d think that would have worked to get those who were most at risk of being stranded or trapped out first, then everyone else could make the determination as to whether or not to evacuate on their own. That would have limited the traffic jam to an extent and it certainly would have mitigated the potential danger to citizens.
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