Superior Plus in 12 m radius curve. From drawing is apparent how two middle car sections and their trucks are connected by mechanical coupling. This mechanical coupling provides minimum yaw angle of truck rotation relative to the car body, improves significantly guiding forces between wheel and rail and provides the widest car body for TTC Structure Gauge. Thsi mechanical coupling is of simple and reliable design which is proven in operation of 435 pieces of KT4 streetcar vehicles produced by CKD Prague for many Europeean cities. These vehicles have been in revenue operation for more than 20 years.