Heavy traffic on the street where you live severely limits your ability to know your neighbors and to enjoy the outdoors.

That's the conclusion of a new study, released Thursday, that shows heavy vehicular traffic has profoundly negative impact on the lives of New Yorkers. Compared to neighborhoods with low traffic volume, 1,000 or fewer cars per day, residents living on streets with more than 5,000 vehicles per day:

• Have more negative feelings about their block;
• Have fewer friends in the neighborhood;
• Are more often interrupted during sleep, meals and conversation;
• Spend less time walking, shopping and playing with their children.

According to the 14-month study,"Traffic's Human Toll,'' by Transportation Alternatives, a nonprofit group that advocates biking, walking and better mass transit, 49 percent of the residents interviewed said reducing traffic would "totally improve'' their quality of life. On heavier traffic streets, the percentage was even greater, 62 percent.

The study found that residents living on the heaviest-traveled streets tended to keep their windows shut and their curtains drawn; live more in the rear of the house; forbid children to play on the street; and avoid certain streets when shopping.

The study's researchers recommended that the city reduce traffic by 15 percent by 2009 by improving mass transit and adding bike paths.

It also recommended implementing "traffic calming measures,'' such as reducing speeds, expanding the use of speed bumps and prohibiting truck traffic.

And it proposed "congestion pricing,'' where motorists are charged a flat daily fee for driving through designated zones at certain times of the day. That revenue would be reinvested in public transit. In Central London, where congestion pricing was introduced in 2003, traffic congestion was reduced by an average 26 percent, Transportation Alternatives said.

In the "Traffic's Human Toll'' study, 21 researchers interviewed more than 600 residents in four neighborhoods: Astoria, Queens; Brooklyn Heights, Brooklyn; Chinatown, Manhattan; and High Bridge, the Bronx.