Don’t end 2011 on a sour note by having your New Year’s Eve plans derailed by traffic issues. Closures begin well before midnight, making a transportation game-plan vital for anyone planning to hit the Strip. Here’s what you need to know:

Know your closures. The I-15 off-ramps at Tropicana, Flamingo and Spring Mountain will shut down at 5 p.m. Saturday, according to Nevada Department of Transportation officials. Strip closures begin at 6 p.m. As NDOT spokeswoman Michelle Booth says: “People either want to avoid it or get in before 4 p.m.”

The Fremont Street Experience closes to the public at 5 p.m. and reopens at 6 p.m. for entertainment. (Closure times are tentative, pending variables such as weather and crowd congestion.)

Know your limits. “Leave the driving to us,” says Tina Quigley, deputy general manager of the Regional Transportation Commission of Southern Nevada. The RTC is offering free transit services from 6 p.m. Saturday until 9 a.m. Sunday, and partygoers can avoid the hassle of driving by parking in one of the RTC’s park-and ride locations. Street closures force alternative routes for some lines, such as the Deuce on the Strip and the Strip & Downtown Express. Those will be detoured from about 4 p.m. Saturday until 4 a.m. Sunday. People heading to the Strip for New Year’s Eve via transit should take the east-west routes, according to RTC officials.

Watch safely. For those hoping to catch a glimpse of the fireworks from Interstate 15—think twice. Nevada Highway Patrol troopers said no-parking signs will be posted along the highway, and troopers will be issuing tickets to stopped vehicles.