Seattle Public Schools added over a dozen school buses Monday after several weeks of low-staffing significantly delayed routes.

An additional 15 school buses will be added Monday morning to the fleet that services students in the Seattle School District.

The district announced the move Friday, saying the added busses will “improve reliable student transportation service” for its students.

“I am frustrated that the start of school hasn’t been smooth for all of our students and families,” said Seattle Public Schools (SPS) Superintendent Denise Juneau. “Our students deserve timely, predictable transportation to and from school.

SPS said many bus drivers employed by First Student, the company contracted by the district, left after last year. Since those departures, First Student has struggled to fill the open positions. Some buses have been forced to add additional routes, leading to significant delays.

SPS said it is taking the following steps to improve bus service.