The assumption was that you have 800 train cars and that you would load roughly 33 cars every 10 minutes.

But let's take your numbers: 415K passengers per day. Let's keep the same three day evacuation period. That's ~1.2 million people. Leaving 5 million in Houston.

Here's the point: Evacuating millions of people over a weekend is a gargantuan task. Magic words like "train", "plane", or "automobile" don't instantly solve the problem.