[This post has been updated]

Transportation agencies are still considering what steps they would take in the face of a shutdown.

Countdown to closure:

The government has been preparing workers for the possibility of a shutdown if Republican lawmakers and the Obama administration are unable to reach an agreement by Friday.

Metro officials said the transit authority would continue to operate on a normal schedule, but might make adjustments to the number of rail cars in service and reduce the number of eight-car trains serving rail lines. The shutdown could reduce Metro ridership 5 to 20 percent, officials estimated.

Members of the Gotta Swing & Lindy Hop Dancers dance down the parade route on Constitution Ave. during the 2010 National Cherry Blossom Festival Parade. (Ricky Carioti/WASHINGTON POST)

Metro provides about 800,000 rail trips and 400,000 bus trips each weekday. Federal workers make up about a quarter of the ridership. If there is a government shutdown and fewer people need transit to get to work, Metro and other transportation agencies may see a corresponding drop in revenue. The minimum regular charge for each trip is $1.95 for rail and $1.50 for bus when using electronic fare cards.

That could mean trouble down the line depending on the length of the closure. Metro raised fares last year to help cover a budget deficit and already faces a $72 million shortfall for the budget year that begins in July. The agency attributed a portion of its shortfall last fiscal year to a drop in ridership as portions of the vast transit network were closed due to the record snowfall that blanketed the Washington region.

The Maryland Transit Administration says that its MARC trains and Commuter Bus service would operate as scheduled for the immediate future. However, the MTA would consider operating reduced services if there was a prolonged shutdown, officials said. Virginia Railway Express officials have said they plan to run full service in the event of a shutdown.

Drivers might encounter a bright spot over the weekend:

The U.S. Office of Management and Budget says if a federal shutdown occurs the Cherry Blossom Parade scheduled for this weekend will be canceled, the Post’s Ed O’Keefe reports. The parade is planned for 10 a.m. Saturday on Constitution Avenue between Seventh and 17th streets NW. Cherry blossom festivities run through Sunday. But if marchers don’t step off roads that would be closed are likely to remain open.

How would a shutdown affect you? Post a comment below.