BROOKLYN - Friday marks the start of the Labor Day holiday weekend, but AAA says more people in Brooklyn and the rest of the country will be avoiding the roads.The organization says it expects less than 29 million people to travel by car to a holiday destination this year. The number is about 100,000 less than the amount of people who traveled in 2006.One reason for the decline, according to the group, is the price of gas. While gas prices are about 10 cents cheaper this year, AAA says they are still very high by historical standards.AAA insists there will still be plenty of people heading out though, as the overall number of Labor Day travelers will hit 34.6 million.