[This post has been updated.]

Travelers undaunted by the oppressive heat that the Capital Weather Gang forecasts for this weekend may venture out to Nationals Park for the weekend series against the Rockies (bet they wish they were back in Denver), take in minor league action with the Bowie Baysox or Potomac Nationals, or listen the music of John Williams at Wolf Trap on Saturday.

It’s also a big weekend for the beach and mountains, so remember my summer getaway suggestions. During Monday’s online chat, some travelers were asking about best and worst travel times for this week. There may be some extra traffic on the Interstates and at the Bay Bridge toll plaza this afternoon, but it’s nothing to be feared.

With the holiday right in the middle of the week, many people who were going to get away have already gotten there. But do look for some extra visitors heading to our main tourist destinations in the D.C. area.

They planned their trips long before the forecast called for a heat wave. While many of us restock our derecho-depleted refrigerators, they’ll be outside no matter what the temperature. So will the crews working on road and rail projects throughout the region.

Metro disruptions

[6:30 p.m. Friday update] Metro has cancelled what would have been an extensive weekend’s worth of track work affecting all lines. The cancellation, a very unusual step because of the amount of preparation involved in setting up the maintenance projects, followed the derailment of a Green Line train near the West Hyattsville station at 4:45 p.m. Friday. About 55 passengers were safely evacuated, the transit authority said.

We’ll keep you updated about the status of service on the Green Line. After the derailment, service was suspended between Fort Totten and Prince George’s Plaza. Metro called in shuttle buses to bridge the gap.

Excessive heat

Because of the extremely high temperatures, Metro is allowing riders to drink water aboard trains and buses and in stations through Sunday. This temporarily suspends the policy barring eating or drinking within the transit system.

If the Metrorail car is hot, don’t just sit there. At the next station, try another car. The cars have their own cooling equipment. Riders can usually tell the difference between a car that’s warm because it’s hot outside and a car with an air-conditioning problem, so trust your feelings.

Use the intercom to report the hot car to the train operator.

I’ll have more tips about travel during periods of extreme weather on Sunday’s Commuter page in The Post’s Metro section.

Beltway/Telegraph Road

While commuter traffic will gradually ease through August, drivers continue to have difficulty getting through the Capital Beltway work zones between Springfield and the Woodrow Wilson Bridge. Workers are paving both Beltway loops to finish up the THRU and LOCAL lane configurations.

This weekend, watch for inner loop ramp closings at Telegraph Road in the Alexandria area. Crews will be paving between the Metrorail bridge and the Cameron Run bridge.

The work is scheduled to be done by 5 a.m. Monday.

495 Express Lanes

A disruption also will occur on the west side of the Beltway in Virginia. This one is part of the 495 Express Lanes project, also known as the HOT lanes.

Three lanes of Interstate 66 West at the Beltway are scheduled to be closed from 10 p.m. Friday to 8 a.m. Saturday. After midnight, the fourth lane may be closed for up to half an hour at various times throughout the night, but a full stoppage of traffic is scheduled for 1 a.m. to 2 a.m.

Crews also will close Exit 49, from the outer loop to I-66 West. Traffic will be directed to continue on the outer loop to Exit 52B, for Little River Turnpike East, the to follow signs for I-495 North (the inner loop) to Exit 49A, for I-66 West.

If bad weather forces cancellation of the Friday night work, it will be rescheduled for the same hours on Saturday night.

Route 355 paving

The Maryland State Highway Administration is resurfacing the intersection of Route 355 and Route 27 in Germantown. Northbound Route 355 between Henderson Corner Road and Route 27 is scheduled to close from 8 p.m. Friday to 5 a.m. Monday. Watch for detours.

Dulles Metrorail project

Westbound I-66 between Route 267 and Route 7 is scheduled to close from 11 p.m. to 5 a.m. Sunday through Friday nights. The Dulles Metrorail project will be working on the Silver Line bridge that crosses the highway.

Montgomery storm pickups

The Montgomery County Department of Transportation announced that it will be making special storm tree debris collections on county- maintained roads starting Wednesday.

Crews will pick up tree debris placed by the roadside. Be sure the debris placed for collection does not block sidewalks, driveways and streets. The collections will take several days to complete.

Bay Bridge times

All summer long, the best times to use the Bay Bridge are Thursdays and Fridays before 10 a.m. and after 10 p.m., Saturdays before 7 a.m. and after 5 p.m., and Sundays before 10 a.m. and after 10 p.m.