Cary, N.C. — The Wake County Public School System administrator who oversees the district's transportation and facilities departments announced Monday that he plans to resign Dec. 31.

Until then, Don Haydon, the school system's chief facilities and operations officer, will be on paid leave, effective Tuesday, according to school system spokeswoman Cris Mulder.

Haydon has been with the school system since 2002.

Mulder said that Haydon has agreed to assist the school system in its efforts to find a replacement.

It's unclear why Haydon is stepping down. The school system gave no reason, and school board members said they were surprised by the decision.

School board Chairman Kevin Hill called Haydon a "very good administrator" who was put up against a huge obstacle this year with the implementation of a new student assignment plan.

Board member Keith Sutton called Haydon a "consummate professional," and John Tedesco said that, although he wasn't certain, that he felt perhaps Haydon just wanted to move on.

"I am saddened," Sutton said. "I respect him a great deal. I think he is exceedingly knowledgeable."

Haydon could not be reached for comment Monday.

His resignation comes as the school system is looking to change for the second time in as many years how it assigns students to school.

The district is also working to correct problems with its busing schedule, which has affected thousands of students across the district.

Earlier this year, the school board cut the number of buses in service in an effort to cut costs.

But since the start of the traditional-calendar school year last month, parents complained about buses being late or not arriving at stops.

Those complaints led Wake County schools Superintendent Tony Tata to apologize publically to parents.

The district has since also put about three dozen additional buses into service.