Patent GB-698254-A (GB)
Title: Improvements in or relating to traffic signals
IPC: G08G1/085
Filed: 1950-08-25
Abstract: 698,254. Road signals for controlling traffic. SIEMENS & HALSKE AKT.-GES. Aug. 25, 1950 [Aug. 25, 1949; Feb. 1, 1950]. No. 21117/50. Class 118 (ii). A relay circuit for controlling road traffic signals in more than two phases permits the signals to be operated in any desired phase sequence. For each pair of signal groups displaying opposite main signals there is provided a main group relay and a subsidiary group relay the contacts of which operate the signals in the desired sequence, and each of the combinations of pairs of signal groups which are simultaneously changed are controlled by a phase circuit energizing the appropriate main and subsidiary group relays. To permit operation in any desired phase sequence there is arranged in at least some of the phase circuits one winding of subsidiary group relays of a plurality of other phase circuits. Circuits are described for both normal and divided phase working and also arrangements whereby all the signals may be set to red in the event of a traffic breakdown. An auxiliary circuit permits automatic working in a fixed phase sequence. Fig. 3 shows a circuit for controlling six different traffic directions in three phases as illustrated in Fig. 2, the directions being grouped in three pairs AB, CD, EF which are required to display opposite main signals. In the figs, a red stop signal is indicated by a filled-in circle, a yellow change-over signal by a hatched circle and a green clear signal by a circle containing a cross. A, C and E are the main group relays, B, D and F the subsidiary group relays, and I, II and III phase relays controlled bv manually operated switches S 1 , S 2  and S,. Considering first the condition when phase II is in operation. Relays C, F and B are operated through contact d, and all other relays are released. As a result the following signals are on in accordance with the condition set out in Fig. 2: stop signal AH, clear signal BF, clear signal CF, stop signal DH, stop signal EH and clear signal FF. To change from phase II to phase III, switch S 3  is operated to energize relay III. Contact. 3 applies voltage to relays B and D. Relay D operates, opening contact d, and breaking the phase II circuit and releasing relay F. Relay B remains held over the phase III winding and relay C remain held over winding C'. Due to this change-over of subsidiary relays D and F, change-over signal Cz replaces clear signal CF and change-over signal Fz replaces clear signal FF. No change occurs in signal group AB. This condition is maintained as long as switch S is closed thus determining the duration of the change-over period. Upon release of S 3 , relay III releases and contact 3 opens. Relay E then operates via contact f, opening contact e 2  and releasing relay C. A holding circuit for winding E' is completed via contact e 3 . Due to this change-over of main relays C and E, red signal CH and green signal DF are switched on reversing group CD whilst red signal FH and green signal EF are switched on reversing group EF. No change occurs in group AB. Phase III conditions are therefore established as indicated in Fig. 2. Subsequent change from phase III to any other phase takes place in like manner under control of switches S 1 -S 3 . A modification of the control circuit, Figs. 6 and 7 (not shown), provides a tacility whereby, in the event of traffic breakdowns, accidents, &c., it is possible to give the red signal in every direction after first showing the change-over signal in directions showing green. This is effected by providing each subsidiary group relay with a further winding by which it is possible simultaneously to alter all their switching conditions. Fig. 8 (not shown) illustrates a modification of the lamp circuit to include red and green pedestrian signals which change-over with the traffic signals. In further modifications, Figs. 9 and 10 (not shown) a yellow signal is included in the change from red to green. Fig. 11 illustrates an embodiment in which the individual phases are divided into two parts. This is of advantage where, for example, a tramway or pedestrian crossing is to be given right of way for the first part and barred for the second part of a phase. In the Figure group B comprises the normal two-colour signals AH, and AH, which change-over between the two parts of the phase. Group CD comprises normal signals for each direction together with an additional pair of signals CH which give a clear signal for the second part of the phase giving a clear signal for group C. Group EF similarly comprises normal signals for each direction together with an additional pair EH arranged to give a clear signal for the first part of the phase which gives a clear signal for group E. The control of the phases is effected as in Fig. 3 by manually-operated switches S 1 -S 3 , the switching-on of a second part of a phase being effected by operating the switch a second time. It is possible to change to another phase whilst operating the first part of a phase without first switching to the second part of the phase. Considering first phase II to be switched on by S 2 . Contact 2 energizes relays B and F and on release relay C operates and holds via winding C'. Thus in group CD, stop signal DH and clear signal CF are on whilst auxiliary signals CH remain. with stop signal CHH on. This constitutes the first part of phase II. When switch S 2  is closed again an auxiliary main group relay CH operates through contacts 2 and c, holding itself via winding CH'. Contact CH then changes the auxiliary signal lighting the clear signal CHF. This constitutes the second part of phase II. The change to phase III proceeds as described with reference to Fig. 3, the auxiliary signal CH remaining at clear however during the change-over period since relay CH is not released until relay E operates to open contact e,. In the case of phase III, the auxiliary signals EH are controlled by a relay ES which operates via contacts e 3  at the beginning of the first part of the phase. The auxiliary signals accordingly change-over with clear signal EHF on and remain thus until S, is closed to initiate the second part of the phase. Relay EH then operates and at contact eh' releases relay ES which changes back the auxiliary signals with stop signal EHH on. The operation for group AB is generally similar, the contacts ch and as of relays AH and AS changing over the auxiliary lamp groups AH, and AH 2  between the two parts of the phase. Figs. 12a, 12b, 13a, 13b (not shown) illustrate a modification of the arrangement shown in Fig. 11 to include a change-over signal in the auxiliary signals. Figs. 14a, 14b, 15a, 15b (not shown) includes in addition a second auxiliary signal group without a changeover signal. Fig. 16 (not shown) shows an arrangement similar to that described in connection with Fig. 6 (not shown) for use with a divided phase system and providing the facility whereby, in the event of breakdowns, accidents &c., the signals may all be set to red. Figs. 18-20 (not shown) illustrates an arrangement in which the number of phases is increased to 4 and the number of signalling groups to 14. Automatic working. Fig. 17 (not shown) illustrates a stepping switch operated through a resistance-condenser circuit for automatically switching the phase relays I, II and III in a fixed sequence. The switches S 1 , S 2  and S, are retained for manual operation in any sequence.