CHICAGO (CBS) — Teachers at Passages Charter School in Edgewater have authorized a strike, making it the third charter network in the city to do so in the last seven months.

Organizers announced the approval of a strike vote Thursday, with those in favor voting 43-0. The bargaining unit has 46 members in all.

No walkout date has been set, according to a statement from ChiACTS Local 4343, the union representing the teachers, teaching assistants and paraprofessionals.

Negotiations have been in the works for about a year and the union says the school, which serves about 500 students, has “failed to produce a fair contract.”

A charter school network has never gone on strike anywhere in the United States.

In February, the ASPIRA network of charter schools on the Northwest Side voted to strike but ultimately came to an agreement with management. The UNO network avoided a teachers strike in October 2016.

(Source: Sun-Times Media Wire © Chicago Sun-Times 2017. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)