The Nation’s Triathlon, seen here in its 2010 edition, draws thousands to swim, bike and run in the Potomac River corridor. (Dayna Smith/For The Washington Post)

Even as summer wanes, the pace of outdoor, traffic busting activity picks up in the D.C. region. The highest impact events are likely to be the Nation’s Triathlon and the NFL game at FedEx Field. But there are plenty of festivals, including the Prince George’s County Fair at Rosecroft Raceway, the Maryland Seafood Festival at Sandy Point State Park near Annapolis and the Columbia Heights Day Festival on 11th Street NW.

Sunday is likely to be the better of the two weather days. There’s a chance of storms on Saturday, the Capital Weather Gang says.

The Nationals are on the road. The Mystics have a 4 p.m. game Sunday at Verizon Center. The Maryland Terps have a football game at noon Saturday, so watch for extra traffic in College Park and on the Capital Beltway.

[See more weekend activities in the Going Out Guide]

It won’t be easy getting to D.C. area events via Metrorail this weekend because of the rebuilding program. Trains on the Red, Orange, Silver, Blue and Yellow lines are scheduled to operate every 24 minutes. More details on that and on some of the big events are below.

Nation’s Triathlon
The annual Nation’s Triathlon will close many streets in the Potomac River corridor of the District and Arlington County on Sunday morning and early afternoon. Most of the street closings and detours are scheduled to be in effect between 6 a.m. and 1:15 p.m. Sunday. The run, bike and swim event is set to begin at 7 a.m.

Streets will reopen after the last participant has passed by and the race support equipment has been removed. The course will be marked with “No Parking” signs about 72 hours before the start.

Both the start and the finish are in West Potomac Park. This creates an issue for participants, because of its relative isolation and lack of parking.

Car drivers will not be allowed to drop off passengers along Independence Avenue. The event sponsors recommend dropping people off on Constitution Avenue, from where they can then walk across the Lincoln Memorial grounds, or along 17th Street SW, where they can walk down Independence Avenue. Shuttles will be available to take people from the host hotel, the Washington Hilton, to the Transition Area from 4:30 to 6:15 a.m. The Transition Area will be south of the Lincoln Memorial. The shuttles will run about every 20 minutes.

Metrorail opens at its usual time, 7 a.m., so that’s no good for the athletes, but spectators could use these stations for various parts of the event: Smithsonian, L’Enfant Plaza, Foggy Bottom, Arlington Cemetery and Pentagon. Parking at Metro lots and garages is free on weekends.

The D.C. Circulator bus’s National Mall route will detour around the road closings. So the normal stops will be bypassed at 15th Street SW/Jefferson Drive, 15th Street NW near Maine Avenue, East Basin Drive SW at Jefferson Memorial, West Basin Drive SW near Independence Avenue and Lincoln Memorial Circle SW. Until 3 p.m. temporary stops will be added at Henry Bacon Drive and at Constitution Avenue/18th Street NW.

Football at FedEx
Kickoff for the season opener is scheduled for 1 p.m. Sunday. This means extra traffic in Landover, on the Capital Beltway and on the D.C. freeways.

Most FedEx parking areas open four hours before game time. The new RedZone permit parking area, which offers wider parking for tailgaters, will open five hours before game time. It’s on the west side of the stadium and can be reached via Belle Haven Drive.

The stadium gates open two hours before kickoff. Before and after stadium events, traffic surges on Landover Road, Central Avenue, Baltimore-Washington Parkway, Southeast-Southwest Freeway, Interstate 295/D.C. 295 and the eastern side of the Capital Beltway. Football traffic will be at its heaviest in the two hours before kickoff. Three Beltway interchanges at Landover Road, Arena Drive and Central Avenue offer access to FedEx Field. As game time approaches, the Landover Road and Arena Drive exits tend to be the most crowded. Central Avenue, the southernmost of the three exits, is the one that the Maryland State Highway Administration recommends to minimize delays approaching the stadium.

The highway administration also suggests that drivers going west on Central Avenue consider bypassing the right turn onto Brightseat Road and turning right instead on Morgan Boulevard to reach their permit parking areas.

On the Beltway in Landover, through traffic should stay as far left as possible. The right lanes will slow. Approaching the stadium area, Beltway drivers will notice a solid white line separating through lanes on the left from the collector-distributor lanes on the right that lead to off-ramps and on-ramps.

Morgan Boulevard on the Blue and Silver lines is the closest Metrorail station to FedEx. The stadium is a little less than a mile north along a sidewalk. The walk to the stadium is slightly uphill. Largo Town Center station, at the east end of the Blue and Silver lines, is the next closest. Make sure you have your SmarTrip card or paper Farecard loaded for a round trip so you won’t have to wait in long lines at fare vending machines after games.

Metrorail
On all lines but the Green, the scheduled gaps between trains will be greater than normal from 10 p.m. Friday through the system’s midnight closing Sunday. Trains will operate 24 minutes apart on all but the Green Line, but there are some other details to know about the work zones, where trains will share tracks.

Red Line. Crews will work on the tracks between Shady Grove and Twinbrook and also between Judiciary Square and Rhode Island Avenue. In those zones, trains will take turns on the open track.

Orange Line. Trains will share tracks while crews work on the track bed between Vienna and West Falls Church and also between Eastern Market and Stadium-Armory.

Silver Line.
Trains will share a track between Eastern Market and Stadium-Armory.

Blue Line. Trains will share a track between Pentagon City and Arlington Cemetery and also between Eastern Market and Stadium-Armory.

Yellow Line. The trains will end northbound trips at Mount Vernon Square, rather than continuing on to Fort Totten as they normally do on weekends. Board a Green Line train to continue farther north. The Yellow Line trains will share a track around a work zone between Pentagon City and L’Enfant Plaza.

Green Line. The Greenbelt rail station will be closed Saturday and Sunday while Metro continues to work on the test track between Greenbelt and College Park for the new rail cars. Free shuttle buses will take passengers between Greenbelt and College Park, but weekenders who normally park at Greenbelt may want to park at College Park instead to avoid the bus trip. Between College Park and Branch Avenue, the trains will operate on their normal weekend schedule.