Runners leave the starting point on Constitution Avenue in NW D.C during the 2014 marathon. One runner carried an American flag. (Sarah L. Voisin/The Washington Post)

The District will host more than 25,000 runners for the annual Rock ‘n’ Roll Marathon on Saturday, an event that is set to disrupt traffic, parking and transit in all four quadrants of the city.

The marathon takes runners through many of the District’s neighborhoods between 7 a.m. and about 2 p.m., closing numerous streets and causing painful gridlock in the nation’s capital.  This year, residents and visitors should anticipate even more challenges as D.C. police implement stricter parking restrictions along the route.

The good news is Saturday now looks like a partly sunny and dry day.  The Capital Weather Gang tells us to expect light winds and highs in the mid-40s to near 50.

The marathon starts at 7 a.m. from a line on Constitution Avenue NW at 14th Street and finishes mid-afternoon at Robert F. Kennedy Jr. Stadium. In between, residents will feel trapped in their neighborhoods, while travelers will need to plan ahead to reach Reagan National Airport, Union Station and other destinations.

Most of the street closings will be in effect from 6 a.m. to about 3 p.m. There are some earlier closures:  Constitution Avenue will be closed from 2 a.m. to noon between 15th and Ninth Streets NW.  East Capitol Street NE, from 22nd Street to 19th Street NE will be closed from 2 a.m. to 3 p.m.

Here’s how the race will impact your neighborhood. The  A complete list of street closures provided by D.C. police is here and by the marathon organizers here.

If you live in the District and park on the street, watch for “No Parking” signs along the route. Streets generally reopen as the last runners pass by.

D.C. police won’t allow vehicles to remain parked on the route, requiring hundreds of car owners to move their vehicles before the event. The parking restrictions are part of a new policy to keep vehicles away from special events such as parades and races to protect pedestrians and crowds from terror-inspired attacks where vehicles are used as weapons.

“The public should expect parking restrictions along the entire marathon route and should be guided by the posted emergency no parking signage,” police said in a statement. “The public should also expect enforcement of these parking restrictions which may include ticketing and towing along the entire marathon route.”

The event sponsors have a discount deal with SpotHero, so drivers can look for off-street parking within walking distance of the start and finish lines. Shuttle service will be provided from the finish line (RFK Stadium) to the start line.

Marathoners should plan to use an alternative to Metro, which isn’t going to be an option for them because the rail system opens at 7 a.m., just when the race starts.

But, half-marathoners— and there are many of them—  have a good shot at reaching the 8:30 a.m. start via Metro.

If you are planning to use the bus Saturday to get around, you may encounter some delays and detours.

About 35 Metrobus routes in the District will be impacted from 4 a.m. through 3 p.m., Metro said. The transit agency recommends riders allow additional time to their travels and use Metrorail as an alternative. A list of affected bus lines and the detours is available here.

The D.C. Streetcar will suspend Saturday service along H Street and Benning Road NE until about noon or after the marathon passes.

D.C. Circulator will modify two bus routes  Saturday. The Mall route will delay opening until 10 a.m. The Woodley Park-Adams Morgan-McPherson Square route will detour around its stops near Harvard Street NW. Some stops will not have service between 7 a.m. and noon.