This is expected to be the biggest Labor Day travel weekend since 2008, with slightly lower gas prices encouraging more people to take that last summer vacation, according to AAA projections. And with most of those travelers expected to hit the road, it also will be one of the more dangerous.

You probably figure the odds are about 1 in a billion you’ll be killed on the road during the long weekend. In reality, chances are more like 1 in 87,848 that you’ll die in a car crash between now and Tuesday.

You can improve the odds against your survival by taking any one of a few simple steps: Don’t wear your seat belt. Do fiddle with your mobile device while driving. Knock back a few drinks before you set out.

“Unfortunately, this weekend will be a time of tragedy for hundreds of families,” said Deborah A.P. Hersman, former chairman of the National Transportation Safety Board and now the head of the nonprofit National Safety Council.

Hersman’s group did some calculations based on past years and estimated that 395 people will die nationwide during the long weekend, the traditional end to the summer-vacation season. If that proves true — and Safety Council estimates have been fairly on target the past few years — the number of dead will be comfortably below the 473 killed in 2008 and the 508 killed in 2007. In 2012, the most recent year for which statistics are available, 378 people were killed in crashes over the holiday weekend.

According to AAA’s annual projections, an estimated 34.7 million people will travel 50 miles or more from home for the holiday. Most of them — 29.7 million — plan to drive, according to AAA’s survey.

About 842,000 of those travelers will set out from the Washington area, a slight increase from last year. Gas in the Washington region is averaging $3.39 a gallon, AAA said, about 5 cents less than the national average.

Of those Washingtonians who travel 50 miles or more from home, said John B. Townsend II of AAA Mid-Atlantic, nearly nine out of 10 — 87 percent — will make the trip by automobile.

Townsend said air travel by Washington area residents will be a tick below last year, with an estimated 64,200 people flying, and that 42,900 others say they will escape by rail, bus or boat.

So, what’s the best time to hit the road?

“If past trends hold true this Labor Day, holiday travelers departing the Washington metro area for the weekend will find slowing traffic beginning at 2 p.m. on Friday and the worst time to travel between 5 and 6 p.m.,” Townsend said. “The best bet for drivers is to wait until after 7 p.m. on Friday or before noon on Saturday to help ensure valuable vacationing time isn’t spent in standstill traffic.”

There tends to be more travel on Labor Day weekends that begin in August — as opposed to those that fall entirely in September — because schools in some regions don’t open until September. Confidence in the economy also has encouraged more people to travel.

“This year, Americans are more optimistic about their financial situation,” said AAA’s chief operating officer, Marshall L. Doney. “Consumer spending continues to outpace disposable income, indicating that Americans are comfortable using their credit cards to take one last summer vacation this year.”

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