Patent GB-403732-A (GB)
Title: Improvements in or relating to traffic control signals
IPC: E01B9/22
Filed: 1932-06-30
Abstract: 403,732. Road signals for controlling traffic. AUTOMATIC ELECTRIC CO., Ltd., Strowger Works, and RENSHAW, P. B., Brookwood, Alder Road, West Derby, both in Liverpool. June 30, 1932, No. 24843/33. Divided on 403,720. [Class 118 (ii).] In a system in which a number of control signals are regulated from a master controller the following features are provided : (1) if the local units are time controlled, their individual equipment affects the signals at a slower rate than the rate of the master controller so that the individual units only effect complete control when the master equipment is not in use ; (2) certain movements of the equipment are always locally controlled to ensure a predetermined minimum shewing for all signals ; (3) the master controller sends control pulses to the controlled units at different times during its cycle to maintain the phase relationship required with the progressive type of traffic control systems; (4) the master controller sends signals to the local units only when signal changes are to be made and the signals sent vary with the change to be made so that a local unit receives each type of signal only once during its cycle ; (5) emergency equipment enables all the signals at all or any of the local units to be put at danger; (6) manual control equipment is fitted, and (7) if the local units are pad-operated the master equipment is only effective during maximum timing conditions and then need only affect the changes on one of the two routes. Specifications 403,720, and 403,731, the description in which is identical with part of the description in this Specification, and Specification 356,102 are referred to. Normal arrangement, time-controlled equipment. The master equipment shewn in Fig. 1 controls three distant units, over banks 1a, 2a and 3a of DST respectively, the equipment controlled over 2a being shewn in Fig. 2. The system is operated from A.C. mains 10, 11 transformer XFR supplying rectifying valve VLV which feeds the neon lamp N, and metal rectifier bridge MRA which supplies DSM, F and the signalling lines. The condenser QB charges, at a rate determined by the position of pointer 12, and N flashes, operating E which connects current to the wipers of DST and energizes F. F pulls up, maintains the current circuit to the wipers of DST, energizes DSM, shunts E and the neon lamp N and flashes the master fail alarm lamp MFA. E falls away and after the slow period of F, DSM steps and the cycle is repeated, signal pulses being sent to the controlled units when a wiper of DST is resting on a connected contact, the pulses being heavy or light as determined by the connection of resistances in the circuits. The pulses are transmitted to the various units at different points in the cycle of DST, to maintain the phase relationship required for progressivesignal systems. The local control equipments comprise cam shafts fitted with twenty-two cams and having six positions, the shafts being rotated by solenoids such as S, Fig. 2. All the cams are not used in the system described and are not shewn in the figure. The cams closed in the various positions of the apparatus are marked M in the chart shewn in the figure. With the cam shaft in its first position, cams 1, 9 and 22 are operated ; cam 9 lights the green signal GNS for the north-south road, cam 22 the red signal for the east-west road and cam 1 completes a circuit for condenser QA. The circuit to QA includes part of a resistance 13, the amount of resistance being so adjusted that QA charges in say 10 seconds. The neon lamp IN flashes, A operates and S steps the cam shaft into its second position in which the lamp signals remain unchanged but cams 2 and 7 close. Cam 2 connects power to the condenser QA through an adjustable tapping to resistance 13 (the connections to 13 not being shewn) which is adjusted to include a large amount of 13 in the circuit so that QA is charged at a very slow rate. Under normal working QA is not charged in this circuit as DST reaches a contact connected through a resistance to the equipment and a light pulse is received which operates B. As cam 7 is closed the condenser QA is charged over this circuit, A and S operate and the cam shaft moves to its third position in which cams 3, 10 and 22 are closed. The east-west signal remains red but the north-south signal changes to amber. If desired the amber signal can be shewn to both routes at this time by connecting up as shewn at 14. Cam C3 connects the power to QA through an adjustable tapping to 13, which determines the time of the amber signals and when QA is charged, IN flashes and the cam shaft steps to its fourth position, changing the east-west signals to green and the north-south signals to red. Cam C4 is closed and, being wired in parallel with C1, after about 10 seconds, the switch is stepped to position 5 where the signal lamps are unaltered but C5 and C18 are closed. C5 is connected in a similar manner to C2 and its connection is normally ineffective as 2a of DST now again reaches a connected contact and a heavy pulse is transmitted over the control wires to energize B and C, B being ineffective but C completing a low resistance charging for QA to step the cam shaft to its sixth position. The amber signal is now shewn on the east-west route for a time determined by the connections to C6, when the shaft is rotated to its initial position and the cycle is repeated. Non-inductive resistances are connected across the signal wires to prevent operation of the system by surges and inductive discharges. Operation in the event of failure of the master equipment or of line faults. Should the master equipment fail, the cam shaft is stepped from positions 2 and 5 when QA charges up over C2 and C5 respectively, the time of operation under these conditions being somewhat slower than under normal working. A similar operation occurs when a line fault occurs unless the line fault is such as to maintain either or both relays B and C energized in which case the switch steps from 2 and 5 immediately it reaches them and the apparatus works at a faster rate, the rate being determined by the connections to 13 which control the stepping in the other positions of the cam shaft. Special controls. The closing of contacts ARS by a manually operated key energizes the relay AR at all sub-stations which opens the circuit of QA to stop further movement of the cam shaft, opens the circuits of the green and amber lights and joins the circuits of the red lamps. As one of the red lamps is always illuminated all signals are thus set at red. In operated, the additional resistance YG is shorted and QA charges quickly to again operate A and step the shaft to position 2 giving the right of way to the E.W. route. a further position of the manual key, contacts css 1, 2 and 3 are operated to disconnect power from the master impulser circuit and energize relays CS at all sub-stations to open the supply circuits. In a third position of the key, contacts css 1 and 2 only are operated to disconnect the master controller, the local units then working as independent units. A key at the local equipment controls contacts MAN, which disconnect the impulsing circuits at MANI and at MAN2 enable the apparatus to be controlled by push button PB. Contacts ARS1 and 2 allow an individual unit to be set at " all red." The lamp MFA flashes in synchronism with the transmitted impulses so that failure of the impulse circuit is indicated. Road-pad-operated system. Figs. 3 and 4 indicate the local equipment of a road-padoperated system, the master controller being brought into use only under maximum timing conditions. The switches INS, VNS, IEW, VEW, LNS and LEW are wired to appropriate tappings of resistance 20 whilst switches MNS and MEW are wired to resistance 21. It is assumed that the cam shaft is in position 6 and that there is no traffic in either street. The right of way is for north-south and condenser QA is charged over C4. If a vehicle arrives on the east-west route, contacts DEW are operated and D energizes and locks. QA discharges over FA and A operates to energize S which steps the shaft to position 1 giving the amber signal to N.S. and, if the dotted connection is used, amber-red to E.W. The condenser is now charged over C 13 and LNS and, as E is not A further charging circuit for QA is now completed over C14 and IEW and, as D is still up, the shaft is stepped to position 3 where D falls away. The lights are unchanged but QA is now charged over C15 and VEW. If further vehicles arrive on the E.W. road, D is again energized whilst the vehicles are on the ramp and QA discharges over C16, giving a time extension to the route, the allowance being less for fast moving vehicles than for slower ones as they are in contact with the ramp for less time. Should a vehicle arrive on the N.S. road, E will be operated to complete the circuit for A, so that should the gap between vehicles on the E.W. road be sufficient to allow QA to charge, A is energized and the cam shaft is moved on to position 6. Should the traffic on the E.W. road be substantially continuous however the maximum timing circuit becomes operative. As soon as relay E is energized and locks a circuit is completed over e2, C17, MEW and C12 to charge QB, which charges at a much slower rate than QA. As the road N.S. is the main road, contacts C8 are closed in all positions of the shaft but position 6 so that when QB is fully charged, B is energized and the cam shaft steps on to give right of way to the N.S. road. Had the shaft been in position 6 however when the maximum timing became operative, contacts C8 would have been open and the energization of B would have been held up until the receipt of the correct pulse from the master equipment had energized C. The instants at which right of way is withdrawn from the main road traffic is controlled by the master controller and may be adjusted in phase to permit main road traffic