Abstract: Priority is given to the movement of buses at intersections controlled by traffic lights, by lengthening the duration of the green lights on the street on which the bus approaches the intersection, and shortening the duration of the red lights, not only in response to the presence or absence of the bus, but also in accordance with the total amount of traffic on that street and the cross street. For each of the streets on which buses travel, there are provided "mini-green" programmer wheels which permit display of the green for two time periods of minimum duration on the relevant street, one time period corresponding to flowing traffic and the other to non-moving traffic. On each street where buses travel, there are also "time extension" programmer wheels, which permit setting of two time extensions of the duration of the green light on the associated street, again for flowing traffic and for non-moving traffic.