Holiday travelers make their way over the Chesapeake Bay Bridge. For summer weekends, the transportation authority has outlined optimal times to cross the bridge and avoid congestion, includingThursdays before 2 p.m., Fridays before noon and Saturdays before 7 a.m. (Michael Lutzky/THE WASHINGTON POST)

The D.C. region is sinking into its summer traffic patterns, emphasizing vacation getaways over local commuting. So drivers plotting their escapes have been asking for updates on highway bottlenecks they might encounter.

Dear Dr. Gridlock:

We traveled the New Jersey Turnpike several times in the last few months. South of the merge (between the cars-only and truck lanes around exit 8A), all traffic both northbound and southbound is diverted to the new three-lane sections of the road.

For about 25 miles, the six-lane main portion of the highway sits empty, with little evidence work is being done on it — maybe a truck or two every few miles with four or five workers. As traffic piles up and slows down, it is extremely frustrating to see that empty highway just sitting there!

Can you find out when the target date for completion is?

Susan Gillespie, the District

The massive, $2.3 billion project to widen the turnpike between exits 6 and 9 in the middle of New Jersey has slowed travelers for several years. But it reached a milestone this spring when the new lanes at the sides of the highway opened to traffic.

For the time being, that means traffic that was using the old inner lanes has been pushed onto the new outer lanes so the construction can continue in the middle. The widening project is scheduled to be done by Thanksgiving, which the turnpike authority says would be an on-time finish.

For southbound drivers, that lane merge in the 8A area has long been a notorious choke point. On weekends, when truck traffic is light, I find the merge is easier if approached from the truck lanes rather than the car-only lanes.

Here’s the latest on some other highways that worry vacationers.

Interstate 495 in Delaware. It’s unlikely that travelers will be able to use this Interstate 95 dodge in Delaware before Labor Day. Repair work on the now-closed I-495 bridge over the Christina River is moving rapidly, the Delaware Department of Transportation says. But it’s a big job, involving installation of 32 steel-reinforced concrete shafts below ground to strengthen support for the bridge.

The bridge closing has two effects on travelers from the D.C. area: They can’t use I-495 to bypass the I-95 traffic in downtown Wilmington, and the traffic on I-95 to and from Philadelphia is more congested, though the lanes are open.

I’ve been watching the traffic maps and cameras. Recently, the I-95 traffic in the Wilmington area has not been so severe that vacationers would want to detour just to avoid the city — unless they plan to pass through at rush hour, or on a Friday evening, when traffic is normally heavy.

If you do feel the need to detour, the shortest route is to follow Interstate 295 as it splits to the right from I-95 south of Wilmington. Take I-295 to the Delaware Memorial Bridge (toll). From there, either continue on I-295, which exits to the right, or take the New Jersey Turnpike (toll). This is the one that makes the most sense to me given recent conditions in Wilmington.

There’s a more significant deviation in which a driver can approach I-95 in Delaware via Maryland’s Eastern Shore, but note that the traffic volumes are likely to be higher during summer travel season, especially on weekends. For this trip, take Route 50 across the Chesapeake Bay Bridge, follow Route 301 to Route 896 (Churchtown/Boyds Corner roads) to Route 13. From there, drivers can reach I-295 and the Delaware Memorial Bridge.

Chesapeake Bay Bridge. For all summer weekends, the transportation authority says the best times to cross the bridge are: Thursdays before 2 p.m., Fridays before noon or after 10 p.m., Saturdays before 7 a.m. or after 5 p.m., and Sundays between 7 and 11 a.m. or after 10 p.m.

Some drivers have asked about the signs warning that headlight use is mandatory on the bridge at all times. They ask whether their daytime running lights, the ones that come on automatically on some vehicles, meet the safety requirement. Sgt. Kevin Ayd, a spokesman for the Maryland Transportation Authority police, told me that they do.

I-95/395 in Northern Virginia. The place where getaway traffic is most likely to be slowed is very close to home, in the 29-mile construction zone for the 95 Express Lanes between the Capital Beltway and Garrisonville Road in Stafford County. There’s no sense worrying about any of the other bottlenecks I mention and not taking this one very seriously in your travel planning.

This is a rough stretch at any peak travel time because of the enormous volume of traffic, but on many summer weekends, sections of the HOV lanes on I-95/395 will close for the express lanes project. This means you can’t use the HOV lanes in the middle of the interstate during the hours they normally would be open to all traffic. And it means that all traffic will be squeezed into the regular lanes.

Drivers can avoid the work zone by swinging out east or west. To the east, there’s Route 301, which crosses the Potomac River via the Nice Bridge (toll). Drivers could link up with I-95 south of Fredericksburg via Route 207. To the west, drivers can take Routes 28 or 29 to Route 17, which links up with I-95 just north of Fredericksburg.

Most highway departments will suspend road work around the July Fourth and Labor Day weekends. That means they will pull up the orange cones and barrels, but the lane shifts, lane narrowings and rough pavement will remain in place.

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