The United Automobile Workers union said Tuesday night that the three Detroit automakers had agreed to address concerns about coronavirus hazards to factory workers by taking steps short of shutting down U.S. production.

General Motors, Ford Motor and Fiat Chrysler had been resisting calls by the union to shut down their plants for two weeks to minimize the spread of the virus among factory workers. In separate meetings with the U.A.W. on Tuesday evening, the union said, the companies promised a variety of measures to keep workers apart inside factories and to extend time for cleaning work stations and common areas.

“All three companies have agreed to new measures that will increase adherence to the C.D.C. recommendations on social distancing in the workplace,” the U.A.W. president, Rory Gamble, said in a statement, referring to the Centers for Disease Control and Prevention.

He added that the three companies had agreed to partial shutdowns at certain times to allow for thorough cleaning of plants and extended periods between shifts. Shift schedules at some plants may be altered to reduce the number of workers entering each day.