Hurricane evacuation areas would encompass 640,000 more city residents, and the number of zones would double, under plans disclosed Friday.
Details on the new zones won’t be released until June, but the changes could mean neighborhoods around the city might newly be told to clear out ahead of future storms, even as the city grapples with findings that nearly two-thirds of people shrugged off orders to leave before Superstorm Sandy.
As officials reckon with a new understanding of flooding risks after Sandy, they aim to expand both the size and the number of zones so they can tailor evacuation orders better to the dynamics of a particular storm, Deputy Mayor Caswell Holloway said.
The idea: “Only dislocate the people who need to be dislocated and ultimately give people more confidence” that evacuation is necessary, he said at a briefing to release the city’s self-analysis of its handling of Sandy.
More than 2.3 million people live in the city’s three evacuation zones now. The roughly 375,000 residents of the most vulnerable area, called Zone A, were ordered to leave a day before Sandy walloped New York on Oct. 29.
Mayor Michael Bloomberg gave several public briefings urging them to go, and the city sent out text-message alerts and dispatched police cars with bullhorns to some neighborhoods.
And yet a city-commissioned survey of 509 Zone A residents found 63 percent stayed home, according to the report released Friday.
Nearly three-quarters of them said they’d gotten the message that they were supposed to leave. But they didn’t for a range of reasons, mainly that they thought the storm wasn’t strong enough to imperil them or that their homes could withstand it. Some said they wanted to protect their property from damage or looters, or they didn’t think the storm would hit.
The choice proved fateful for some New Yorkers. Sandy killed 43 people in the city, almost all of them in Zone A. Thousands of homes were destroyed or damaged, and an estimated 1 million residents lost power citywide.
Getting people to heed evacuation orders has bedeviled officials around the country for years. Often, one-third to half of residents defy mandatory evacuation orders, experts say.
Some governments have tried dire warnings about the dangers of staying behind, moral appeals not to endanger rescuers, and laws that threaten fines or jail time. In New York — where a little more than half the survey respondents said they thought the city could have done more to encourage evacuation — Friday’s report calls for seeking to use digital billboards and making sure orders emphasize what’s at stake.
“People need to believe, first of all, what you’re telling them: that the situation is serious. … But people need to believe, also, that if they leave, there’s somewhere for them to go that’s safe and what they leave behind will be safe. And we’re going to continue to push those messages,” Holloway said.
The current evacuation zones are based mainly on storm surge risk projections, neighborhood geography and how accessible an area is by bridges and roads. The new zones come as federal flood map revisions are poised to double the number of homes and businesses in flood zones, and the evacuation maps also will take account of such factors as the direction in which a storm is traveling.