I believe they estimated at least 2 million, maybe almost 3 million Houston & surrounding area citizens evacuated Rita. Many of us seem to think that so many evacuated because it was so soon after seeing the horrors of Katrina, plus our local media over-hyped the coverage, like repeatedly playing animated surge models, maybe 2-3 times per hour -- reaching as far inland as the 610 Loop
). I was already prepared, but after watching those surge animations all day, begged hubby to evacuate about 1 1/2-2 days before landfall.
We evac'd from the south side of Houston (zone c, which is only mandatory evac for cat 4+) in our truck with dual fuel tanks. The traffic was so heavy that we would have run out of fuel had it not been for our second tank (the truck isn't the most fuel efficient).
Requests for contraflowed freeways were made for almost 24 hours before they finally arranged for them, then they took many hours to set up contraflows because of the cities along the contraflow had to have extra personnel (officers, National Guard, and State Guard) to enforce contraflow, and TxDOT's sloppy plans and implementations. But eventually, contraflow did allow us to begin moving at a continuous rate, even if it was slow for quite a while).
http://en.wikipedia.org/wiki/Hurricane_Rita#TexasOther things that slowed evacuation were numerous wrecks and breakdowns. It seems like the contraflow helped with a lot of the breakdowns, which causes me to guess that many breakdowns were due to over-heating in the 100 temps. It was reported that more people died in the evacuations than in the actual hurricane, but Rita ended up hitting the Tx/La border, which isn't as densely populated as the Houston area.
There were lots of 18 wheelers, towed camping trailers and RVs that slowed things down too. I can understand wanting to bring camping trailers and RVs in case someone lost their home, or just had to stay away for at least a week or more, but those 18 wheelers certainly didn't help move traffic any faster. If it was up to me, I'd let the 18 wheelers evac 3 or 4 days before landfall, but not after mandatory evacs were ordered.
As our only calm weatherman predicted, Rita changed direction and headed towards the Tx/La border, but by that time, the citizens in Rita's path couldn't evacuate because the freeways north and west of them were parking lots. And even though Rita struck the border, she was big enough to slightly flood my area (per neighbors reports), and knock out power for a few days.
IIRC, there were hardly any problems with evacuating Ike, even though there weren't any contraflows. My guess is that people that could evac early did, and many others didn't because of how terrible Rita's evac was. Plus, Galveston waited until the last minute to declare mandatory evacuation, which might have affected Houston's evacuation had Ike become stronger.
As far as the zoned/timed evac plan, it's my opinion that it only slightly works for disasters known in advance. Our local forums had many Houstonians from the NW sides of town talking about evacuating Ike because they had children, and didn't want to be without power with children. Many people of Katy, Tx were totally freaked even though Katy is west of Houston, and pretty far inland. And with Ike, the media was much calmer than they were with Rita, due to public backlash about scaring so many people into evac'ing Rita. So that's why I think that zoned evacs will only work to a certain degree, because fear triggers
flight, no matter how many people are in more danger behind them.
Flooding came within a few inches of entering my home with Ike, and did flood a few of my neighbors' homes, whose houses are a few inches lower than ours. I've been through 2 hurricanes now, but neither flooded me. I've had my home flooded twice in non-hurricane situations. One of our large trees roots became exposed after Ike, and two of our neighbor's large trees fell in our backyard. Between our four large trees surrounding this house (that's also been through Carla '61), and the realistic threat of flooding, we'll probably evacuate if we're still living in the same location. But we're thinking we'd wait until approximately 6-8 hours before landfall, after reading someone's comments after Rita, that it only took him a few hours to travel at least 100 miles by waiting until just before Rita was supposed to hit. According to his comments, if traffic was too bad, he had enough time to turn around and ride it out at home, which is what we'd do if there was still heavy traffic that close to landfall. And after TxDOT's experience with Rita, if a strong hurricane threatened the Houston area again, they'd probably do better with contraflowing with one round of contraflowing in their experience.