Centro works in partnership with bus operators, local authorities and other organisations to improve the quality of bus services in the West Midlands. Buses provide 92% of public transport journeys in the West Midlands and account for nearly one million journeys a day. There are a number of operators, the largest being National Express West Midlands, which accounts for 77% of all journeys made. The Rotala and Arriva groups have also extended their interest in the region through the acquisition of smaller bus companies.