WEST PALM BEACH, Fla. — Problems with school bus routes and late buses have hampered the School District of Palm Beach County since school started last week, but district officials said that progress is being made in resolving the issues.

The district’s new superintendent, Robert Avossa, said that implementing a new routing system before the beginning of the school year left little time for testing and training. He also noted that the district did not have enough school bus drivers to cover all of the routes in the required timeframe.

“It is not uncommon to have some complications at the beginning of the school year, but the level of problems we have had with transportation is unacceptable,” Avossa said in a letter in which he apologized to parents last week.

The School District of Palm Beach County runs a large transportation operation, with a fleet of about 600 route buses shuttling some 58,000 students daily.

Early last week, the district pulled together a group of staff members to work with the transportation team on resolving the busing issues, and the number of phone lines in the transportation call center was doubled.

On Friday of last week, Avossa and Mike Burke, the district’s chief operating officer, held a briefing to provide updates on the transportation situation. As one sign of progress, about 26% of buses were running late that morning — down from 40% on Monday the 17th, the first day of school.

Also, the district tripled its bus routing team, from six to 18, to input new routes into the system. Staff members worked over the weekend to enter routing changes. Schools were to call parents when new routes were posted, and students were to get printouts of their routes this week.

On Wednesday, the district again apologized to parents and thanked them for their patience.

“Progress has been made, but we are not yet where we need to be to provide the level of service our students and families deserve,” district officials said.

New school bus routes are going into effect on Thursday and Friday in an effort to resolve the remaining transportation issues. The changes were communicated directly to students and parents on Wednesday, and the district’s “Find My Bus” website was put back online after new routes were processed.

“Our focus is to correct the remaining issues and build the transportation operation that our students deserve,” district officials said.