Heading out to party on Halloween? Metro might make getting there — and getting home — into a real-life zombie crawl. (Photo by Evy Mages/For The Washington Post)

Standard reminder: the Washington Regional Alcohol Program will be offering free rides home through its SoberRide service from 10 p.m. Saturday to 6 a.m. Sunday. Call 1-800-200-TAXI to get up to $30 in free cab fare. (Terms and conditions apply; check the WRAP site for details.)

Nightmare on the Red Line

From 10 p.m. Friday until closing on Sunday, trains will single-track between Union Station and Dupont Circle. Metro advises that “trains operating through the work zone (between Dupont Circle and Union Station) will operate every 20 minutes in each direction.”

That’s not a treat, especially for those coming to the 17-stop Nightmare on M Street bar crawl on Saturday night, or any of the dozens of other parties taking place.

Some basic advice for those needing to get to the affected areas: Use the $1 Circulator bus. If you’re coming from the Shady Grove end of the Red Line, get off at Woodley Park and take the Circulator to Adams Morgan, U Street and Dupont/Logan circles. Those coming from the Glenmont branch, Greenbelt or the Yellow Line can grab the Circulator at U Street or Columbia Heights. Orange and Blue Line riders can get off at McPherson to get a ride to Adams Morgan, walk to Dupont from Farragut West, or take the Rosslyn-to-Dupont Circulator to get around the mess.

The Ghoulish Green Line

The four Green Line stations closed this weekend are Waterfront south to Congress Heights, which means trouble for people coming from Anacostia or Prince George’s County, but no worries for those heading from other areas to parties on U Street or in Columbia Heights.

However, this doesn’t bode so well for those going to Truckerboo, the Halloween-themed food truck festival at the Bullpen on Friday night. Twenty-five trucks will serve up treats from 11 a.m. to midnight, and there’s a contest with a $250 prize for best costume and $500 for best group display. Those will be announced at 11 p.m., and you must be present to win. Problem is, the Navy Yard station across the street, which is how most Truckeroo attendees usually get to the event, closes at 10 p.m. and won’t reopen until Monday morning. If you intend to stick around for the contest, there’s a Bikeshare station nearby and it’s an easy ride to the Eastern Market Metro — which is open as usual.

For Marine Corps Marathoners

Metro starts running trains at 5 a.m. Sunday to accommodate the 30,000 participants in the Marine Corps Marathon and the 10,000 in the Marine Corps 10K, which begin at 7:45 a.m. Since the Blue and Yellow lines are maintenance-free this weekend, there shouldn’t be too many problems getting to the start of Sunday’s marathon -- as long as you’re coming from Virginia. Marylanders and Washingtonians have fewer choices for getting around the single-tracking. (We know, the idea of getting up even earlier on race day doesn’t appeal.)

We expect the large parking lots and garage at New Carrollton to be put to good use, but trains are single-tracked between New Carrollton and Cheverly, and Metro suggests adding at least 20 minutes to your trip. We’ve covered the Red Line single-tracking in D.C. above. The Dupont-to-Rosslyn Circulator isn’t really an option in this case, though, because it doesn’t start running until 7 a.m. Spectators coming from the Bethesda branch of the Red Line, we maintain that this is the easiest way for you to go cheer on the race course.