A busy stretch of Beach Drive that’s been under construction, seen here in October, won’t be completed until August as part of an overhaul of the entire 6.5-mile road. The construction has caused nightmarish traffic problems in the area. (J. Lawler Duggan/For The Washington Post)

It could be August before a busy stretch of Beach Drive NW reopens to vehicular traffic, officials said, disappointing thousands of commuters who have endured nightmarish traffic since the route closed for improvements last September.

Work on the section between Rock Creek and Potomac Parkway and Tilden Street was expected to be completed this spring. But officials with the National Park Service say crews need more time to complete reconstruction of the road and its adjacent trail. For drivers, it means at least two more months of getting around a work zone through a busy part of Northwest Washington.

Beach Drive, a 6.5-mile roadway that runs through Rock Creek Park, is undergoing a total makeover. Work began Sept. 22 on the stretch near the National Zoo — the busiest portion of the road. After this segment is completed, three other closures along the route will follow, with a projected completion date of fall 2019. The current closure is likely to be the most painful, however, as some 26,000 cars travel the section daily and are now being diverted to other clogged arteries such as Connecticut Avenue.

“We understand that this is a real inconvenience to drivers and pedestrians and bicyclists,” said Jeremy K. Barnum, a spokesman for the National Park Service. “We are doing everything we can to get the work done all at once … so we are not back there in the near future disturbing the route again. It is fundamental that this be done right.”

The $32.9 million project is the first complete reconstruction of Beach Drive in 25 years, and is in response to years of complaints about gaps and cracks in the road, and a trail that has become rough, root-laden and uneven.

The extra time will allow the contractor, Fort Myer Construction, to perform work on the trail and road simultaneously and “more efficiently manage the work,” Barnum said. This includes widening the trail, which is used for commuting and recreation by hundreds of cyclists, joggers and pedestrians. Doing the work concurrently ultimately will avoid closures in the area later on, city and Park Service officials said.

Still, some residents and commuters question the approach. At community meetings last summer, the Park Service along with the contractor and city officials, said the road and trail work were included in the original time frame of six to eight months. The original plan was to rebuild the road first, then the trail, which would allow foot and bike traffic all through the project. Now that the two are being done concurrently, the Park Service has put in detours for pedestrians and bicyclists.

The portion of Beach Drive between Piney Branch Parkway and Porter Street, which was left open to allow east-west traffic through the park, will close by midsummer, officials said. Crews will then move to the second phase of the project, which will close the stretch of Beach Drive between Tilden Street and Broad Branch Road. Officials say the work there will take between two and three months to complete instead of the projected six to eight months.

After repairs are completed on that section, crews will move to the area between Broad Branch Road and Joyce Road, then finally, the part between Joyce Road and the Maryland border.

Park Service officials say the overall project is still on track for completion in the projected three-year period. There haven’t been any major storms to disrupt work and just a few unanticipated events, such as the discovery of some cables and wires under the road surface and a historic wall under the road near Tilden Street, officials said.

A bigger challenge has been keeping foot traffic out of the construction zone. A few near-misses between construction vehicles and pedestrians and cyclists last fall prompted the Park Service to step up enforcement to keep the foot traffic from veering off the designated path. Construction crews installed additional fencing and signage to prevent people from entering the closed area, officials said.

Nanci Link, a retired nurse who lives in Northwest Washington, said the closure has made it more difficult for her and her husband to get around. The couple, for example, has cut back on volunteering from five times a month to twice a month, she said.

“The park closure also makes it difficult — very stressful — to get to doctor appointments in Foggy Bottom,” said Link, 73. She’s also noticed more traffic on neighborhood streets and longer backups near the zoo, she said.

“Many people used Rock Creek Parkway to get into the zoo which now has not been an option,” she said.

Over the Presidents’ Day weekend, when springlike weather drew thousands of visitors to the zoo for a send-off for the panda Bao Bao to her new home in China, delays of more than 30 minutes were reported along Connecticut Avenue, the zoo’s other entrance. As spring and summer roll in, Link says the area needs to prepare for similar traffic nightmares near the park.

But, she said she hopes the timeline for completion of the work isn’t extended even more.

Shutting down an entire road for months at a time is rare and D.C. officials said they do so only as a last resort. In this case, the Park Service said a closure was necessary because the road is too narrow to accommodate traffic plus all the construction, staging and equipment needed.

“This isn’t just filling potholes and repaving it,” Barnum said. “We are excavating the entire area, putting down the new gravel base, working on the trails and in some cases on storm drainage issues.”

When the work is done, the popular commuter route will have new traffic safety features — such as guardrails and centerline rumble strips to keep drivers from drifting into oncoming traffic.

City transportation officials meanwhile say a new traffic pattern appears to have stabilized. Data in the month following the closure showed modest increases in congestion along Connecticut Avenue, with two minutes of additional travel time in the southbound lanes and four minutes northbound, according to the District Department of Transportation. Similar patterns were recorded for other alternate routes such as 16th Street and Georgia Avenue NW, officials said.

Officials are still urging commuters to travel via other modes or outside peak hours if possible. Traffic control officers are still being deployed to ensure good traffic flow, and officials continue to monitor and adjust traffic signal timing to reduce the queuing conditions. The city also added new signs and markings.

Maura Danehey, a DDOT spokeswoman, said the extra two months of closure near the National Zoo will benefit the District because it will mitigate future traffic impacts that would have resulted from building the trail separately. Some of the work, she said, will also be done during the summer when traffic tends to be lighter.

“While these changes have resulted in some disruption and delays, the overall system has been resilient as we have been able to make minor modifications to signal timing and roadway configurations to accommodate the new flows,” she said. “We will continue to be proactive in our approach throughout all project stages.”