A streetcar rolls down H Street. (Photo by Evelyn Hockstein/For The Washington Post)

After a year of labor-relations skirmishes, dozens of District streetcar workers voted Friday to join the union that represents thousands of Metro employees.

The vote came just days after the District’s fledgling streetcar system started carrying passengers for the first time.

The Amalgamated Transit Union had first planned to hold a union election early last year, but a group of operators were fired shortly before the scheduled vote.

The ATU accused streetcar operations contractor RDMT and staffing agency Midtown Group of unfair labor practices, and argued in an action it brought before the National Labor Relations Board that the companies had fired the employees to stymie their union organizing effort.

But the labor relations board concluded in December that streetcar operators had violated a no-cellphone-use policy and that their firings were legal.

The NLRB also found that two fired streetcar employees who damaged a streetcar while moving it in the maintenance yard had “failed to follow proper procedure.”

Allegations that the firms interrogated employees about their union sympathies and threatened them with losing their jobs if they unionized were settled in an NLRB-approved agreement between the companies and the ATU in December.

As part of that settlement, the companies were required to read aloud a series of statements to assembled workers, including: “We will not unlawfully tell you that we will have to remove or get rid of mechanics and operators if employees chose to be represented by a union.”

Union officials said the firms’ statements amounted to admissions of past illegal labor practices, but the companies said they had never violated the law and had no problem saying they would not do so in the future to resolve the case before the NLRB.

In a statement after the successful union vote Friday, the ATU President Larry Hanley applauded “the courageous workers at the D.C. Streetcar, who stood up today and won a more democratic workplace.” Hanley said that “these law-breaking, union-busting contractors” should be removed by the District and the streetcar system’s workers should be made public employees.

Leif Dormsjo, director of the District’s Department of Transportation, said in a statement that the agency “has always been supportive of the rights of workers, including the freedom to organize themselves for collective bargaining purposes. We will work with the system operator to understand the implications of having their employees represented by the union.”

In the coming months the union and companies are set to engage in contract talks determine set future workplace terms.

In a statement, streetcar operator RDMT said “we look forward to bargaining in good faith with the union. We are troubled, however, by the union’s attempts to falsely paint RDMT in a negative light. At this time we choose not to be distracted by name calling and false allegations, and instead will put our efforts into working with the union to best serve the interests of our customer, our employees, and our community.”