Cars travel on Beach Drive, a local route whose planned repair work is expected to disrupt commuter travel. (Christian K. Lee/The Washington Post)

Beach Drive, a busy commuter route in Northwest Washington, is crumbling. Gaps are spreading. Cracks are widening. And the seven bridges along the 6.5-mile long road are eroding.

A segment of the road and its adjacent trail, which runs through Rock Creek Park, will shut down to traffic starting next month, kicking off a three-year rehabilitation. The project promises a brand-new roadway — but also nightmarish commutes.

“When it is done, it is going to be a beautiful facility,” said Matthew Wolniak, a consultant for the National Park Service working on the project. “But in the short term there is going to be pain.”

Lots of traffic congestion pain, that is.

Beginning after Labor Day, the stretch between Rock Creek Parkway and Tilden Street will be closed for six to eight months in what would be the first of four closures along the route.

Thousands of cars that travel that part of the road near the National Zoo — some 26,000 each day — will be diverted to already-clogged Connecticut Avenue.

The work couldn’t start at a worse time for commuters — it coincides with the end of summer, when traffic flows tend to become heavier, and the end of daylight saving time. Commuters aren’t enthusiastic about switching to Metro while the rail system is in the midst of a year-long maintenance program that shuts down portions of track and creates delays.

Beach Drive, which is narrow with curvy sections, will get a complete facelift — crews will excavate the entire area and put in a new gravel base before laying new asphalt. All seven bridges will be rehabilitated and parking areas rebuilt. New traffic safety features will be added such as guardrails and centerline rumble strips to keep drivers from drifting into oncoming traffic. The work also includes improved storm drainage.

The adjacent trail, used for commuting and recreation by hundreds of cyclists, joggers and pedestrians, will be widened to 10 feet in areas. There will be new trail construction between Porter Street and Piney Branch Parkway and a new crosswalk on Beach Drive at Blagden Avenue.

Officials say the full closure to vehicle traffic is necessary because the road is not wide enough to allow for work to be done on one half of the road first and the other half later. They say the space is needed to accommodate the construction, staging and equipment. Cyclists and pedestrians will still be able to use the trail during the project.

“Unfortunately, there is a trade-off. There is not one perfect solution,” Wolniak said at a recent community meeting. “It’s not going to be good for six to eight months.”

Beach Drive runs through Rock Creek Park. (Christian K. Lee/The Washington Post)

But the pain won’t end after eight months. When the first phase is completed in early spring, three more segments of the road will be shut down for up to eight months each.

Some residents and Beach Drive users worry that the plan, which in all phases would route traffic to Connecticut Avenue, will overburden a road that is already one of the city’s busiest commuter corridors. At the meeting on Thursday, people who live in the area also said they worried that drivers looking to beat the traffic would speed through residential neighborhoods. Some asked that construction continue around the clock to expedite the progress.

“I don’t see how this is going to work,” said Ann Garlow, who lives in 16th Street Heights and uses Beach Drive daily.

“Connecticut Avenue is not where everyone is going to bleed out. . . . Why is the city not thinking outside of the box and turning some of the larger streets, which are available to them, to turn them into bleed-outs. I don’t get it,” she said. “It doesn’t seem as though anybody is taking the traffic flow into account.”

As many as 26,000 cars travel through Beach Drive in the area near the National Zoo each day, the D.C. Department of Transportation reports. The Park Service says about 40,000 people use Beach Drive for recreational purposes at Rock Creek Park on weekends and that the park welcomes more than 12 million people every year. Park Service and District officials say they plan to monitor traffic and assess detours during the project.

“We understand that traveling the greater Washington area will be tough during this time,” Park Service spokesman Jarod Perkioniemi said. “That’s why we are really trying to get this out now to people that this is coming up and how they can properly plan for it. So they can either adjust their route or start to telecommute more.”

Built in the late 1800s, Beach Drive provides north-and-south access to Rock Creek Park, the nation’s first urban national park. It last saw a complete reconstruction 25 years ago, and officials said most roads last about that long.

A full rehabilitation of the road has been in plans for a decade, but it has been delayed by discussions about widening of the trail, negotiations over stormwater regulations in the District and funding. The Federal Highway Administration in June awarded a $32.9 million contract to Fort Myer Construction.

Meanwhile, Beach Drive has continued to deteriorate, and temporary repairs including filling potholes and patching cracks were no longer cost-effective, officials say. The Park Service spends $75,000 on maintenance of the road each year.

“We had a huge snowstorm last year, so that takes its own wear and tear on the road,” said Perkioniemi. “It’s gotten to the point that the temporary repairs were not working anymore.”

And it is not just those traveling by car who have noticed the deterioration. Many cyclists have chosen alternative routes because of the declining condition of the trail, said Katie Harris, trail coordinator with the Washington Area Bicyclist Association.

The trail is one of the busiest in the area, but its users complain about how rough, root-laden and uneven it has become. Many say the trail, which was built to be eight feet wide in some sections but is narrower in other areas, is not wide enough to handle daily traffic.

“A ride on the trail is a bumpy one due to tree roots cracking the asphalt,” Harris said. “The edges of the trail have deteriorated due to years of unattended grass and weed overgrowth. This has also reduced the usable width of the trail, which was insufficient to begin with.”

In addition, the trail was built with challenging 90-degree turns approaching bridges and a narrow sidewalk near the tunnel close to the National Zoo. When the National Zoo closes its gates, trail users are forced to use a three-foot sidewalk in the tunnel. That sidewalk will be widened to five feet as part of the project.

Two years ago, the cyclists’ group collected 2,400 signatures for a petition that called for the Park Service to fix the trail. Now trail users welcome the repairs. Cyclists and pedestrians will be able to use the road during the construction, though the road will close at night. When work is being done on the roadway, people can run on the trail, and when the trail is being constructed they can run on the roadway, officials said.

The second phase will close the stretch between Tilden Street and Broad Branch Road, and that work could begin as early as next spring. After repairs are completed on that section of road, crews will work in the area between Broad Branch Road and Joyce Road. After that, they will move to the final section, between Joyce Road and the Maryland border.

Officials say those who can telework should take that option to avoid what would be likely more painful congestion on Connecticut Avenue and other adjacent corridors, including Wisconsin Avenue and 16th Street NW.

“For us, the importance is the safety of everybody who is traveling through the park, whether they drive, bike, jog or walk. That is what a lot of these improvement are geared towards — making it a safer trip for everybody who is going through Rock Creek Park,” Perkioniemi said.