GB719121A - Improvements in road traffic signalling installations - Google Patents

Abstract

719,121. Road signals for controlling traffic. SIEMENS & HALSKE AKT.-GES. Oct. 29, 1952 [Oct. 31, 1951], No. 27236/52. Class 118 (2). Centralized supervision and control of traffic signals is obtained without the disadvantage of a multiplicity of cables by providing group control apparatus in the neighbourhood of sets of signals automatically controlled thereby, and connecting all the group control stations in common to a central control station with individual lines from group stations to the central station whereby any selected group station may be switched onto the common cabling circuits for supervision and control of that particular group station. Each group station GS comprises an automatic programme selector P to regulate several sets of signalling apparatus S (only one set being shown in the Fig.) in respect of total phase time and the phase time ratio. The programme selector is stepped forward by an electromagnet PW on each closure of a time switch z driven by a clock mechanism. Two contact banks b3 and b4 of the programme selector P are connected by common cabling to the central control station Z through contacts of a relay AN which is controlled over an individual line a1 from the control station Z. If switch n is operated the relay AN is energised and potentials from contact banks b3 and b4 are fed to non-polarised relays N1, N2 and to polarised relays P1, P2 at the central station Z whereby the potentials are analysed to indicate the condition of selector P from the nine possible permutations of no potential, positive, or negative potential on the two lines a3, a4. Control of the group station is obtained by additionally closing switch y which energises a relay U at the group station and disconnects electromagnet PW from time switch z and connects it to line a5, whereupon the switch t may be operated to step the programme selector P until the desired condition is established as indicated by the relays P1, P2, N1, and N2. To return the group station to its normal programme the switch y is released after sufficient operations of t to bring the selector P into its position corresponding to the instant of reconnection. The line a2 may be utilised to listen to operation of the group station selector by means of contacts i operated thereby to apply alternating current via condensers C1 and C2 to a telephone receiver T. A relay R operates at the group station in the event of a fault and its contact r energises relay St over line a1 to sound an alarm at the central station Z. Signalling apparatus S may also be associated with road-pads K.