Mayor Bill de Blasio says he’s optimistic that a school bus strike threatened for Tuesday will not take place.

Drivers plan to strike two bus companies serving 600 routes in Brooklyn, Queens and Staten Island.

The city is working with the companies and the union as they negotiate.

If the drivers walk off the job, parents could choose either free Metro Cards or reimbursement for car travel, including taxis or car services, according to the Department of Education.

A spokesman for the Teamsters union says 85 percent of its members at Jofaz Transportation and Y&M Transit voted in favor of a strike at a meeting Wednesday night.

The union says sticking points were increased healthcare costs and reduced holidays.

The two school bus companies share the same owner and union contract. The strike would involve about 900 workers and thousands of students.

The mayor said that contingency plans will also address the needs of the special needs children.

(AP / WABC News)