The ''Red Principal'', previously known as MetroBus, serves the inner-city urban area, with a maximum distance of . The ''Red Principal'' consists of 17 main lines, identified with the letter "P" with long-distance routes. The stops are usually , with frequent buses in peak hours, about every 10 minutes. It uses large modern articulated buses, such as the Chinese-made Yutong brand, Russian-made LiAZ, or MAZ of Belarus. 