GB317927A - Improvements relating to signalling systems for road traffic - Google Patents

Abstract

317,927. Venning, C. F. D., and Westinghouse Brake & Saxby Signal Co., Ltd. June 1, 1928. Road signals for controlling traffic.-Signalling devices situated at cross roads throughout a district are automatically controlled from a central point through relays at each signalling device. At each cross road a signalling device 1 is provided comprising three signal elements 2, 3, 4, each consisting of four signal lamps, the element 2 showing, when energized, green lamps along the main street NS and red lamps along the cross street EW, the element 3 showing, when energized, red lamps along the main street and green lamps along the cross street, and the element 4 showing, when energized, yellow or caution lamps along both main and cross streets. Two control conductors 7, 8, extend from the point of control C throughout the whole of the district and at each signalling device 1 the energizing windings of the relays A, B, are connected to the conductors 7, 8 through a change-over switch 9. The control conductors 7, 8 are arranged to be alternately connected to the positive supply conductor 5 by means of rotating drum switches 27, 28 operated by a clock actuated mechanism 29, a manually controlled switch 30 being provided so that both conductors 7 and 8 can be simultaneously de-energized. The contacts of the A and B relays are so arranged that when the A relay is energized and the B relay is deenergized as shown in Fig. 2 the element 2 only of the signalling device 1 is supplied with current, whilst when the A relay is de-energized and the B relay is energized the signal element 3 only is supplied with current, and when both the relays A and B are de-energized the caution signal element 4 only is supplied with current. By reversing the position of the switch 9 at any signalling device 1 the conditions of operation will be reversed for the particular device. The switch 9 at any signalling device 1 may also be set into an intermediate or " off " position so that both the relays A and B are de-energized and the caution signal is given continuously by the signal Element 4 thus permitting of non- automatic control of traffic at this point. If it is desired to give a general caution signal throughout the district the switch 30 can be opened. A modified signalling system is described by means of which a special danger signal such as a bell can be made operative at each signalling device throughout the district by means of a switch at the point of control.