I-395 south of Massachusetts Avenue, seen here off-peak, will be covered with a deck for the Capitol Crossings development. (Robert Thomson/The Washington Post)

Drivers on Interstate 395 in the District will start to see some lane shifts this week as work advances on the Third Street Tunnel project. Lane closures should begin next month.

The project will erect a platform above the highway near Massachusetts Avenue, setting the base for the mammoth Capitol Crossings development.

The area bounded by Massachusetts Avenue to the north, E Street to the south, Third Street to the west and Second Street to the east, has been an active construction zone for months, but work so far has focused on utility relocation. Actual work on the highway is expected to begin next month.

This new phase scheduled to begin July 13 will include deep foundation work for the walls that will go up on the highway. This work will carry on until February of next year, and will require the significant changes in traffic patterns.  Some lane shifts on Interstate-395 are taking place starting today.

Here’s what to watch for:

  • Lane shifts: northbound and southbound traffic lanes on I-395 will shift away from the median.  Traffic on the southbound I-395 will shift to the east by about 10 feet this week. Then, northbound I-395 traffic will shift to the west by about 10 feet the week of July 6.  Drivers in the area will see traffic lanes shifting side to side during the eight months of the foundation work.
  • The 2nd Street off-ramp will be permanently reduced to one lane.
  • During peak travel times at least two lanes on both north and southbound I-395 will remain open.
  • During daytime, non peak hours, there will be single-lane closures, to facilitate the caisson and slurry wall construction.
  • Single-lane closures should be expected overnight, between 11 p.m. and 5 a.m.
  • The Third Street and Second Street ramps may be closed occasionally to facilitate heavy construction activities and utility work. DDOT said this will not be a nightly occurrence and the agency will give motorists notice of the closures.

In addition to the changes in traffic patterns, motorists will see a greater number of construction workers and heavy equipment on I-395. DDOT says it anticipates some traffic impact and motorists are encouraged to find alternate routes to their destinations.

DDOT’s traffic systems maintenance manager James Cheeks said analysis of the traffic around the construction site suggests travel delays in the area so far are estimated at seven to 10 minutes.

This DDOT map highlights the construction zone and areas where motorists might experience additional delays due to the construction activities.

The $200  million platform that is being built over the highway overpass will ultimately reconnect neighborhoods split by the freeway and create a more vibrant community in the downtown’s eastern flank, project and city officials and supporters say.

The construction on I-395 between D street and New York Avenue N.W. could last up to four years. This sounds bad for motorists, but an alternative proposed by developer Property Group Partners would have shut down a portion of I-395 to expedite construction. That plan was abandoned last year.  On Monday, Sean Cahill, senior vice president at Property Group Partners reaffirmed the commitment to proceed with construction with the highway open.

DDOT has not received a high number of inquiries or complaints from motorists who travel around the construction site so far, director Leif Dormsjo said Monday. He said commuters and residents can find traffic updates on the project’s Web site.

“We appreciate the public’s patience. This is really the price of progress to move forward on a very exciting, transformative project,” he said. “We are trying to do this in the most responsible way that we can.”