This is going to be a busy weekend for travelers in the D.C. area — even if it doesn’t snow. The Capital Weather Gang’s forecast for Saturday includes the possibility of snow for outlying western areas, but mostly rain for the D.C. area and east. This is the weekend for Halloween parties and the Marine Corps Marathon. But there’s also a lot of work scheduled for Metro, and some for the roads, too.

These are some highlights. Because of the extensive nature of street closings for some events, they’re just summarized here. Later postings today will contain full listings.

Chain Bridge

The District Department of Transportation says the rehab work that led to several weekend closings of Chain Bridge is substantially done, and the department does not anticipate any further weekend closings for this project.

The project’s contractor does expect to close single lanes at off-peak times to complete the work. (Note that Sunday’s marathon does close some streets on the western side of the District, including Canal Road NW from M Street to Reservoir Road.)

Farragut Metro transfers

As of noon Friday, Metrorail riders who want to switch between lines at the Farragut North and Farragut West stations in downtown Washington will no longer have to pay a separate fare, as long as they are using SmarTrip cards.

This virtual tunnel, which Metro has dubbed the Farragut Crossing, will allow for free transfers between the Blue and Orange lines at Farragut West and the Red Line at Farragut North. Just remember it’s a virtual tunnel. You still have to get out and walk between the stations. Riders have 30 minutes to make the free switch between stations.

Metro weekend delays

These delays and schedule changes take effect at 10 p.m. Friday and continue through the rail system’s midnight closing on Sunday.

Green/Yellow lines: Waterfront, Navy Yard, Anacostia and Congress Heights stations will be closed. Free shuttle buses will replace trains between L’Enfant Plaza and Southern Avenue. Green Line trains will operate in two sections, one between Greenbelt and Huntington and the other between Branch Avenue and Southern Avenue.

During this time, workers will be installing new switches outside the Navy Yard station and preparing for installation of new switches outside Anacostia station.

Shuttle bus service will operate between L’Enfant Plaza and Southern Avenue, with stops at Waterfront, Navy Yard, Anacostia and Congress Heights. An express shuttle will operate between L’Enfant Plaza and Southern Avenue with a stop at Anacostia station.

The last train will depart Branch Avenue 20 minutes earlier than usual, at 2:04 a.m. Saturday and Sunday and at 11:04 p.m. Sunday. (People planning to attend Halloween celebrations should pay particular attention to these early departures.)

Riders using the shuttles should allow at 30 minutes of additional travel time.

The Yellow Line trains will operate between Huntington and Greenbelt throughout the weekend.

Red Line: Trains will share a track between Dupont Circle and Judiciary Square. This will clear a safe work zone at Farragut North, where crews will continue work on the city pipes above the station’s ceiling.

From 9:30 a.m. to 9 p.m. Saturday and Sunday, trains will depart every 10 minutes from the ends of the line at Shady Grove and Glenmont. Every other train from Shady Grove station will end its run at Dupont Circle, and every other train from Glenmont will terminate at Union Station.

At all other times, Red Line trains will leave the ends of the line about every 20 minutes. A train from each direction will go through the work zone about every 20 minutes. This will create crowding. Metro suggests that riders consider Metrobus and the D.C. Circulator buses as alternatives through downtown.

The last trains from Glenmont will leave 11 minutes earlier than usual on the weekend nights: 2:26 a.m. Saturday and Sunday, and 11:26 p.m. Sunday. (This schedule also is worthy of note for people planning Halloween celebrations.)

Orange Line: Trains will share a track between New Carrollton and Cheverly while workers install new rails and perform other maintenance.

Every other Orange Line train in the direction of New Carrollton will terminate at Cheverly and return to Vienna. Allow about 20 minutes extra to get through the work zone.

Bay Bridge

A paving project is scheduled for the Chesapeake Bay Bridge this weekend. (Many road projects, especially those involving paving, are heavily dependent on favorable weather.)

From 11 p.m. Friday to 7 a.m. Saturday, and from 9 p.m. Saturday to 8 a.m. Sunday, the eastbound span is scheduled to be closed. The westbound span will be two-way, with one travel lane in each direction separated by a buffer lane.

AIDS walk Saturday

The following streets will be closed for AIDS Walk Washington Saturday morning, beginning at Freedom Plaza in Northwest Washington:

Southbound Pennsylvania Avenue between 14th and 13th streets NW, from 2 a.m. to 2 p.m.; Pennsylvania Avenue from 13th to Third Street, NW; Ninth, 10th and 12th streets from Pennsylvania Avenue to Constitution Avenue, all from 7:30 to 11 a.m.

The event begins with a rally at 8:15 am. The 5K run will begin at 8:30 a.m., followed by the walk at 9:15 a.m.

Halloween SoberRide

Nearly half the nationwide traffic deaths during the Halloween period are caused by drunk drivers, says Kurt Gregory Erickson, president of the Washington Regional Alcohol Program, which once again will sponsor free cab rides home for adults in the D.C. area who shouldn’t be driving themselves.

The SoberRide program will be in operation from 10 p.m. Saturday till 6 a.m. Sunday. Even though Halloween isn’t until Monday, Saturday night is likely to be the high-risk period for drunken driving. During those hours, people 21 and older who celebrated with alcohol can call toll free to 800-200-TAXI (8294) and get a ride home at no cost, up to what would be a $30 taxi fare.

Halloween in Georgetown

Halloween Saturday draws throngs to Georgetown. Some side streets will close starting Saturday afternoon, while others will get very crowded. Parking also will be restricted.

The nearest Metro stations to Georgetown are Foggy Bottom in D.C. and Rosslyn across the Key Bridge in Virginia. Note below that Metro maintenance will affect service on several lines.

Marathon on Sunday

The Marine Corps Marathon will tie up many roadways near the Potomac River in Arlington and the District on Sunday. As always, Metro is the best bet for participants and spectators. The rail system plans to open at 5 a.m., two hours earlier than normal. Extra trains will operate on the Blue Line from from 5 to 9 a.m. and from 11:30 a.m. to 3:30 p.m.

Runners should use the Pentagon station to reach the start line. The Arlington Cemetery station won’t open until after the race starts. Buses that normally use the Pentagon Transit Center will be moved to the Pentagon City station between 4 a.m. and 4 p.m.

Because of Metro’s weekend maintenance program, buses will replace trains between L’Enfant Plaza and Southern Avenue on the Green Line.

The race begins at 8 a.m. in Arlington, then crosses the Potomac River into the District, the returns to Arlington. See a course map.

Tip for runners: Get a plastic SmarTrip card and load it with enough value to pay the roundtrip fare on Metrorail. The lines for the fare vending machines will be very long after the race at the nearest stations. If you use a paper Farecard, encase it in plastic so that it doesn’t get wet from perspiration during your run.

11th Street Bridge

The District Department of Transportation plans to temporarily close the 11th Street SE entrance ramp to the outbound 11th Street Bridge between 10 p.m. and 5 a.m. Monday through Thursday nights this coming week. During those hours, workers will demolish the retaining wall along the ramp.Pedestrian access will be maintained at all times.

Detour: Motorists traveling on M Street SE and 11th Street SE will be detoured to Eighth Street SE to reach the outbound bridge.

Beltway/Telegraph Road

The Wilson Bridge project has scheduled weekend work in and around the Capital Beltway’s Telegraph Road interchange.

Friday, till noon: The right lane of the Beltway inner loop (I-95/495 South) is closed between Telegraph Road and the Eisenhower Connector for roadside improvements.

Friday, 9 p.m. to 5 a.m. Saturday: The left lane of the inner loop will be closed from the Telegraph Road interchange to just before the Eisenhower Connector for paving.

Friday, 11 p.m. to midday Sunday: The two right lanes of the outer loop (I-95/495 North) will close just before the Eisenhower Avenue Connector to just before Telegraph Road to set an overhead foundation, leaving one lane open. The middle lane will reopen at 6 a.m. Saturday, allowing two travel lanes during daytime, but will close again at 11 p.m. Saturday. All lanes will reopen by midday Sunday.

Kalmia Road

The District Department of Transportation will temporarily close the curb lanes on Kalmia Road NW between East Beach Drive and West Beach Drive next week for preliminary work on replacing a culvert in the area.

The curb lanes will be closed between 9:30 a.m. and 3 p.m. Monday and Tuesday. A single lane in each direction will be kept open along this stretch of Kalmia Road.

Metro work at Braddock Road

Crews are scheduled to do track work starting this coming week near Braddock Road station, where Metro needs to replace worn ties and upgrade the surface under the rails. The work will be done at midday Mondays through Fridays over the next three weeks, starting Monday. (They will skip this Tuesday because of a special dedication event at Reagan National Airport.)

This is the train schedule.

Blue and Yellow lines, 10 a.m. to 2 p.m. Mondays through Fridays, except Nov. 1: Trains will share a single track between Braddock Road and National Airport.

Yellow Line trains will operate every 18 minutes between Huntington and Mount Vernon Square. Riders between Mount Vernon Square and Fort Totten should use Green Line trains.

Blue Line trains are scheduled to operate every 18 minutes between Franconia-Springfield and Largo Town Center.

Riders on both the Blue and Yellow lines should add about 15 minutes of travel time.

Maryland toll increases

The fee increases on Maryland’s bridges and tunnels are set to take effect Tuesday. On the Bay Bridge, for example, the toll goes from $2.50 to $4. On the Nice Bridge (Route 301) in Southern Maryland, it goes from $3 to $4. Tolls on both bridges will rise again in July 2013 to $6.

There’s a change in tolling on the Intercounty Connector, but it affects only those drivers who don’t use an E-ZPass transponder. Those who get a bill based on a video recording of their license plate number will see that the $3 Notice of Toll Due fee is replaced with a video toll rate that is one and a half times the toll.

E-ZPass break

Many drivers were upset when the Maryland Transportation Authority, the operator of those toll facilities, imposed a $1.50 per month administrative fee on Maryland’s E-ZPass accounts. So they will be interested in another change that starts Tuesday: The monthly account fee will be waived for accounts used to pay three or more tolls in the previous month in Maryland.

For example, if a driver uses the Intercounty Connector three times in November, the fee waiver will be reflected in the driver’s December account statement.