Patent GB-1187718-A (GB)
Title: Improvements in or relating to Traffic Signal Systems
IPC: G08G1/081
Filed: 1968-08-19
Abstract: 1,187,718. Road traffic signals. SIEMENS A.G. 19 Aug., 1968 [18 Aug., 1967], No. 39559/68. Addition to 1,054,119. Heading G4Q. In a traffic control system, including a traffic control unit as claimed in Claim 1 of the parent Specification 1,054,199, each traffic signal set associated with a highway intersection is controlled by its individual storage register AS p  and comparator V g  and each of the storage registers can be programmed by a signal timetable generator SP g , located at a common control centre Ze, over two links (1), (2). The signal timetable generator SPg includes a synchronous motor Sy driving a punched tape L s . The programme is read into the operational storage register AS p  at the intersection Kr1 by hand operation of key 1 1  which closes relay contacts 1 1  to 1 4 . This allows pulses obtained by monitoring contacts K1, K3 to be fed to the register AS p  and pulse distributer T v . The register AS p  may store 210 bits and after 210 control pulses have been picked up from the tape via K3 the relay I drops out so that the signal timetable generator SP g  may be connected to the register AS p  of another section such as Kr2 by pressing key of contact 2 1  which activates relay II and contacts 2 1 -2 4 . When the storage register AS p  has been programmed the switch Sch2 is closed to connect the timing pulse generator ZT g 1 via control pulse generator StT g  to the pulse distributer Tv. The distributer Tv records the content of the store AS p  step by step in a 14-stage shift register Rg1. A further register Rg2 stores the actual time of running. A once delayed control pulse 14<SP>1</SP> is fed to a comparator Vg which compares the content of the right half of the shift register Rg1 with the content of the register Rg2. If a coincidence occurs the comparator returns the register Rg2 to 0, via link 15. A twice delayed pulse 14<SP>11</SP> adds to the time in register Rg2. When a third delayed pulse 14<SP>111</SP> occurs the actual time in register Rg2 is recorded in register Rg1. After the 21st pulse the green time is available in the right half of register Rg1 for the signal Sg1. The comparator Vg is triggered to carry out a comparison between this value in Rg1 and the actual time in Rg2. The result is fed to a shift register Rg3. After the 28th pulse the " red " time of the signal Sg1 is available in Rg1 and similarly the signals compared in Vg are recorded in a register Rg4. A delayed pulse 210<SP>1</SP> from distributer Tv is applied to trigger bi-stable stores Sp1-Sp14 so that they take over the outputs of registers Rg3, Rg4 and set the switches sp1 to sp14 of signals Sg1-Sg14 accordingly. The pulse distributer Tv produces a twice delayed pulse 210<SP>11</SP> which stops control pulse generator StTg and excites the signal timetable generator SPg via link 2 to pass any pending change of signal timetable to the store ASp. After the finish pulse 210<SP>11</SP> has occurred, if the key T1 is pressed to operate relay I a new programme can be read into the store ASp. The signal timetable generator SPg may alternatively include punched cards, magnetic tapes or other data carriers and may be associated with a teleprinter which may record dates and times of programme changes. The system may be operated in dependence on traffic by means of traffic detectors in which case a data processing system is included which stores several signal timetables one of which can be fed into the storage register ASp on demand from that intersection Kr1. Failure of timing pulses from the control centre Ze, causes after 2 seconds a monostable circuit to return to its rest position and switch in a local time pulse generator ZTg2 to replace ZTg1. Setting all signals to " red " may be provided during blocking of an intersection or when programme changes are made to the store ASp. Having regard to the provisions of section 9 of the Patents Act, the Specification directs attention to the claims of Specifications 1,110,205 and 1,110,206.