The express lanes work zone stretches for 29 miles along I-95 in Northern Virginia and is one of the longest in the nation. (Trevor Wrayton/VDOT)

Travelers in both Maryland and Virginia should be aware of several weekend work areas along Interstate 95 that could slow them down significantly.

 In Virginia

The trouble comes in two parts.

Friday through Sunday nights, starting at 9:30 p.m., the Virginia Department of Transportation plans to close lanes on I-95 South near Exit 148 in Quantico. By 1 a.m., all the southbound lanes will be closed and will remain closed till 4 a.m. Saturday 5 a.m. Sunday and 3 a.m. Monday.

During the work hours, crews will place steel beams for the new Telegraph Road Bridge over the I-95 South lanes. This is part of the 95 Express Lanes project.

All I-95 South traffic will be detoured onto Exit 148, then to Route 1 south to Garrisonville Road and back onto I-95 South. This could delay a southbound trip by 25 minutes.

On the weekend of July 26, the work will move to the northbound side and drivers will encounter half-hour traffic stoppages in all lanes after midnight.

The other part of the pain also is part of the 95 Express Lanes project:

From 11 p.m. Friday to 10 a.m. Saturday, and again from 11 p.m. Saturday to 10 a.m. Sunday, VDOT will close the HOV lanes on I-395/95 from the D.C. line to the end at Dumfries Road (Route 234) for construction. That’s the basic idea, but the sequence is complicated because the HOV lanes are reversible and because project managers are trying to make as much lane space available for weekend travelers as possible.

So by 10 a.m. Saturday, the HOV lanes will open to southbound traffic from the D.C. to the Turkeycock exit (Edsall Road), where all drivers must exit the HOV lanes and merge onto the I-395 South regular lanes. The HOV lanes will remain closed between Edsall Road and the Franconia-Springfield Parkway (Route 289). Southbound traffic can re-enter the HOV lanes just south of the Franconia-Springfield Parkway via a left lane slip ramp. During the work, there will be no direct access to the I-95 South HOV lanes via the Franconia-Springfield Parkway.

By 2 p.m. Saturday, the entire stretch of the HOV lanes will be closed to reverse the direction of traffic.

By 4 p.m. Saturday, the HOV lanes will open to northbound traffic from Dumfries Road to D.C.

Then at 11 p.m., the entire length of HOV lanes is again closed. They reopen by 10 a.m. Sunday for northbound traffic.

I-95 in Northern Virginia is heavily used for summer weekend travel, so there’s likely to be extra congestion because of the lane closings. There aren’t easy north-south alternatives, but those on the east side of the D.C. area could consider Route 301, while those to the west could combine Routes 28 and 17, connecting with I-95 in the Fredericksburg area.

In Maryland

The Maryland State Highway Administration is demolishing the bridge over I-95 at Van Dusen Road, south of exit 33 in Laurel. The work should be done by late summer. During the current phase, watch for closings of the two right northbound lanes on I-95 starting at 8 p.m. Saturdays through Thursdays. The lanes will reopen by six o’clock each morning.

Once work is done above the two right lanes, crews will close the two left lanes.

SHA and state police will sometimes stop all traffic on northbound I-95 for no more than two 15-minute to 30-minute intervals between midnight and 4 a.m. to remove steel beams.

Once the work is done on the northbound side, the process will be repeated on the southbound side.

The north-south alternatives are much easier in Maryland than in Virginia: Routes 1 and 29, or the Baltimore-Washington Parkway (no heavy trucks).