What's truly frightening? How bad traffic is likely to be this Halloween weekend.

Three huge shindigs -- the World Series at Citi Field; the Halloween Parade in Greenwich Village; and the NYC Marathon, which variously zips and plods through all five boroughs on roads that will all be closed to traffic -- make it apparent that driving anywhere will be a nightmare.

If at all possible, take public transportation, said MTA spokesman Kevin Ortiz.

LIRR customers should buy their tickets in advance to avoid waiting in lines after the World Series. Check out MTA Bus Time for bus routes and links to Citi Field.

While extra trains are not yet scheduled for the parade Saturday night, "we'll have them standing by," to be deployed if needed, Ortiz said. Service on the No. 1 train is suspended south of 14th Street between 11:30 p.m. Friday and 5 a.m. Monday for track work for scheduled repairs, so take the Nos. 4 or 5 to Bowling Green or the N or R to Whitehall St.-South Ferry if you need to access Battery Park and the Staten Island Ferry. More information can be found on route changes and bus shuttles at www.mta.info.