It could be next summer before the bulk of the Washington region’s workers return to their offices after months spent teleworking because of the novel coronavirus, according to a new survey.

More than six months after the pandemic hit the region, forcing hundreds of thousands of residents to work from home, many of their employers remain uncertain when and how they will be allowed back in the office, based on a study led by the Greater Washington Partnership.

The survey of more than 400 employers in the District, Maryland and Virginia shows that most are struggling with how to safely bring back workers while the nation remains in the midst of the pandemic, even as states move forward with reopening their economies.

Some companies that had planned to begin bringing workers back after Labor Day have changed course in response to new outbreaks of the disease and employee fears.

Major national employers including Goldman Sachs and JPMorgan Chase said recently they will begin to allow employees to return to their offices in phases over the coming weeks. Some, including Google, have extended work-from-home policies through next summer. Others, such as Twitter, intend to allow employees to work remotely permanently.

Locally, the survey shows that some larger employers are being cautious in their decisions, partly because of uncertainty about the availability of public transit and other commuting challenges for their employees.

“We are now post-Labor Day, and the dates have all shifted back to January or later,” said Joe McAndrew, director of transportation policy at the Greater Washington Partnership, an alliance of chief executives of the region’s top employers. “The level of uncertainty was real [at the onset of the pandemic], and I think it’s still very real now.”

Some 430 employers representing about 275,000 workers in the greater Washington region — stretching from Baltimore to Richmond — participated in the survey conducted from Aug. 10 to 28. Their responses offer a snapshot of what companies are thinking as they weigh resuming in-office operations.

A clear majority of Washington-area employers said they are adopting a phased approach to returning to the office, although many said they remain uncertain about the timing of that return. A third of the region’s employers said they don’t know whether they will have their workers back on site by next summer.

Based on the overall responses, however, about 40 percent of the region’s workforce could be back in the office by spring and 72 percent could be commuting to work by next summer, said Maricelly DiGravio, the partnership’s manager of research.

Only a third of employees are expected to be commuting to their offices this fall.

“Nobody out there is trying to bring their workforce 100 percent by September,” DiGravio said. “The return to worksites will be gradual.”

Telework in the region grew significantly during the pandemic. Before the outbreak, less than 10 percent of the region’s workforce teleworked. The partnership study found seven times as many people have been working from home during the pandemic.

Higher levels of teleworking are likely to continue in the region even after the pandemic, according to a new report by the National Capital Region Transportation Planning Board, which found that more than half of employers anticipate long-term increases in teleworking as a result of the pandemic. According to the TPB report, the average share of employees who teleworked grew to 82 percent from 36 percent at workplaces that already had telework options in place.

Maura Brophy, director of transportation and infrastructure at the Federal City Council, whose staff has also been telecommuting since March, said the fear is that long-term mass telework could become a long-term threat to the downtown office economy and the overall economy of the region.

“This is a moment that really highlights the need for good coordination between the public and private sectors,” Brophy said. “To the extent that we can use this information to inform decision-making among public officials and regional employers, I think that that will set us on a path where we can reopen in a way that’s effective, efficient, safe and also good for our long term economic recovery.”

In addition to reliable transportation, employers said a regionwide coronavirus testing strategy “that is timely, accessible, and affordable” is needed to safely reopen, according to the survey. However, even as most employers said they want to test their employees for the virus, they do not intend to do so if testing costs more than $50 per employee. Only one in 10 employers surveyed said they plan to require employees be tested before returning to the office or worksite.

Smaller companies, those with fewer than 25 employees, are more likely to resume normal on-site operations sooner, the survey found. Those companies reported that about 45 percent of their workforce would be back on site this fall, much higher than companies with more than 1,000 workers, which expect to have fewer than 25 percent of their employees back in the office before the end of the year.

DiGravio said that larger employers appear to have greater concerns about their workers’ commutes, particularly their ability to safely take public transit.

An overwhelming majority of employers said they are concerned about employees’ use of public transportation — with nearly half saying they are “very concerned.”

The survey found 40 percent of employers lacked confidence in the enforcement of mandatory mask policies on the region’s transit systems. Half said they were concerned about crowding and the inability to maintain social distancing aboard trains and buses.

Transportation experts fear those concerns could be exacerbated by recent news that Metro may reduce service if it doesn’t receive more federal funding to help cover the revenue losses it has suffered because of the pandemic.

McAndrew said the survey findings underscore the importance of reassuring businesses and workers that transit is a safe option, and of the need to continue making investments in the system even as ridership remains low. Any reductions in service could hinder the performance of the system, he said.

“If you go ahead and delay frequencies of trains or buses, those folks that need transit are still going to be there when the next [train or bus] shows up. It’s just going to put more people in the car. That crowding becomes more and more of a real issue,” McAndrew said.

To help guide employers and workers, the partnership, in collaboration with Metro and other regional groups, is launching a Transit Tracker, which allows users to track hourly crowding averages on Metro so they can make decisions about when might be the best time to travel.

Crowding has not particularly been a problem aboard Metro during the pandemic. The transit agency last month began restoring service that had been cut during the pandemic and increasing train frequency as ridership picked up. However, concerns remain about crowding as more companies and federal agencies resume normal operations.

According to the partnership study, Metro calculates that a train car can hold up to 23 passengers while maintaining social distancing guidelines of six feet of space between passengers. Aboard a standard 40-foot bus, more than 10 passengers would be considered crowding by social distancing guidelines.

The partnership said it hopes employers will be able to use the Transit Tracker to understand travel patterns in their local stations and make decisions based on the data about shifting work schedules to allow workers to commute when fewer people are in the system.

More than half of employers are talking about staggered days in the office and altering work hours, according to the survey. In addition, 8 in 10 employers are offering alternative work schedules to support employees, and they have embraced flexible and remote work options and policies to help workers deal with challenges during the pandemic.