Rita Joachim didn’t have much faith in the emergency evacuation plans for the lower Hudson Valley before monster hurricanes hit Louisiana and Texas, and after hearing firsthand accounts from former residents of the area who fled Houston last week, she’s even more suspicious.

“It is positively preposterous to think that there is any chance that people could get out of here,” said Joachim, a 48-year-old printer. “Maybe at the beginning of a five-day warning period, but even at three and a half days, we couldn’t. We are so locked in here.”

Two of Joachim’s best friends, fellow graduates of Ramapo High School, drove their families out of Houston early Thursday, beating many of the 1 million people who fled the city and using back roads to get safely out of the storm’s reach.

Rene Forman Derewetzky, a former Monsey resident, said she left at 5 a.m. with a packed car and two kids while her husband was on business in west Texas.

“I made the decision not to take the major highways,” Derewetzky said. “The one time that I had to be on a main road, I sat in traffic. It took me two hours to go 13 miles.”

Both women said getting out of the Hudson Valley would be difficult because of the dense population, the terrain and the overloaded road and transit systems.

“It’s a bad situation there because of all the bridges and people needing to get across them,” Derewetzky said of New York’s northern suburbs. “It would be a nightmare.”

Joachim said local roads and mass transit have a hard time handling the morning rush hour, much less a full-scale evacuation.

“It sometimes takes me 40 minutes to go eight miles to work on the Palisades Interstate Parkway and New Hempstead Road,” Joachim said. “I think the only way to get out in an evacuation would be by bicycle, but it would have to be a mountain bike with fat tires, because I wouldn’t be riding on paved roads.”

County officials on both sides of the Hudson River acknowledge that continual images of Houston residents turning six-lane roads into one-way parking lots raised concerns for emergency planners, but overall the experience there should help Westchester, Rockland and Putnam residents in the long run.

“I think they’re doing a pretty good job in Houston,” Westchester County Executive Andrew Spano said. “Everything has a certain percentage of things that won’t go right. Will we be able to get everyone out if we need to? I’m confident we will. It might not be comfortable for them, but five days is plenty of time.”

Spano predicted a wholesale evacuation would be easier to coordinate for law enforcement and others directing traffic because residents would be largely of the same mind and headed in the same directions.

Rockland County Executive C. Scott Vanderhoef said a regional evacuation would be daunting and likely more difficult than the small-scale evacuations the counties have handled over the years.

“If you’re talking about a mass evacuation like Houston, similar things would happen here,” Vanderhoef said. “The (Palisades Interstate Parkway), for instance, is only four lanes, even if they’re all going in the same direction. We can take care of evacuating people from one part of the county to another, but for a large number of people, at some point our roads will be jammed. The reality is, we’re congested without an event.”

Rosemary Zory, 39, drives every workday from her home in Kent to Modern Media in Norwalk, Conn., where she is vice president of human resources. On Friday, she said she was thinking about evacuations after watching news reports of cars inching away from the expected onslaught of Hurricane Rita.

“Strategically, planning for an evacuation is no small task. I don’t know how you rally the community to make sure people know what to do in an event,” Zory said. “On a good day, it’s hard to get where you’re going. Could you imagine if we had an emergency?”

Hagler Capitalis, 24, a Bronx resident and senior at Purchase College, SUNY, waited for a bus back home yesterday in White Plains and said those relying on mass transit to get away during an evacuation better have a backup plan.

“If it’s early enough, they might be able to get everyone out,” Capitalis said. “But if the situation happens fast, people are going to be stuck. It’s all about reaction time. If you don’t have the financial means to get out on your own, you’re going to have to make a decision to leave even quicker.”

Joachim’s second friend caught in Houston, Peggy Friedrichs, a former resident of Yonkers and Spring Valley, said patience made a big difference in the nearly six-hour trip she made to her parents’ home in Columbus, Texas, a trip that usually takes an hour.

“It wasn’t exactly harrowing,” she said. “It just took forever.””