Despite complaints from parents and board members alike over school bus services, the Shelby County Board of Education renewed its transportation contract Tuesday with Durham School Services.

The four-year contract, approved by a 5-2 vote, is worth $27.8 million.

The company’s drivers were criticized last school year for dropping off students late to class and getting in fender benders. One driver was arrested for possession of marijuana.

However, the company worked with district leaders to improve services and meet goals. Superintendent Dorsey Hopson told board members it would be difficult to change the district’s transportation company with only a month left before the new school year begins.

Hopson said the new contract holds the company accountable to measurable outcomes and enables the district to pull out if Durham doesn’t live up to the deal.

“We have to have accountability for the safety of our children,” said board chairwoman Theresa Jones.

Durham School Services is part of National Express, headquartered in Warrenville, Ill., which operates more than 21,000 buses and serves 550 clients in 32 states and four provinces.