Patent GB-521588-A (GB)
Title: Improvements in traffic control systems
IPC: G08G1/081
Filed: 1938-08-18
Abstract: 521,588. Traffic control systems. NEUHAUS, J. Aug. 18, 1938, Nos. 24335, 24336, and 24337. Convention dates, Aug. 18, 1937, Jan. 17,1938, and July 12, 1938. [Class 118 (ii)] In a traffic control system, the control arrangements at each cross-road are connected directly to a central control station which receives visual or telephonic indications of the condition of traffic at the cross-roads. The normal control of the system from the central station coordinates the signals at the cross-roads according to predetermined normal traffic densities but the signalling periods of the cross-roads may be regulated independently and the co-ordinated control may be replaced by direct manual control at the central station or at the crossroads. Control system, Figs. 1 and 4, mainly mechanical. The control position at the central station comprises (1) a road diagram 1 with lamps controlled from the various cross-roads by the point duty officer to indicate congestion, (2) a series of drums 5 which control the red/green ratio at the various cross-roads, the brushes which determine the ratio being set longitudinally by levers 9, (3) a control handle 10 governing the speed of motor 6 which drives the drums, (4) a control 7 which exercises control in a progressive manner along the main street,on the relative rotary position of the drums, and (5) a series of switches 13 for each cross-road by means of which automatic control is cut out and the signals controlled manually. The control mechanism is shown in Fig. 4 and comprises a series of rotating drums 5, one for each crossroads and consisting of two commutators, one for each road, with conducting portions for the red, amber and green signals connected by wires to the lamp relays. The red, green and amber control portions are separated by helical non- conducting portions so that the red/green ratio is varied by moving the brushes 22, 23 along the drums, this being effected by levers 9. The drums are driven by motor 6. The relative angular positions of the drums are controlled by handle 7 which rotates shaft 38 carrying a spiro-conical cam 40 whereby shaft 42 is rotated. This shaft moves the drums by means of gears 45, 46, the ratio of which progressively increases from drum to drum as the distance of the corresponding cross-roads from the control point increases. The adjustment of the speed of the motor 6 by control 10 involves also a vertical motion of the spiro-conical cam 40, to effect adjustment of the relative position of the drums. Electrical control system, Figs. 8 to 10. The central station equipment for controlling the red/green ratio and times of commencement of the cycles at the various cross-roads comprises a rotating switch R1, Fig. 10, adapted to impulse the wires I ... N, one for each crossing, at times dependent on the closure of switches BI ... BN. The switch magnet is stopped by impulses from a contact of relay B controlled by A which is intermittently energized by cam Q driven by motor M. The central station equipment individual to one crossing say that corresponding to wire I, Fig. 10, is shown in Fig. 9, and the circuits at the crossing are shown in Fig. 8. When the crossing is in the uncontrolled condition, key Ar2, Fig. 9, is open and Arl is in the central position shown, and flashing amber lights at the crossing are operated over Fjc, Fig. 8, and back contacts of relays H and B. To initiate control, key Ar1 is thrown to connect up the impulse wire I and Ar2 to complete the line loop in which H, Fig. 8, pulls up followed by A and B whereby flashing amber is cut off and the red lamps R1, R2 switched on. The impulses on wire I are repeated by J to the line and the resulting impulses by relay H operate and release relays 1A, 2A under the control of relays C, D, E to perform switching cycles on the red and green lamps R1, V1, R2, V2 of the main and subsidiary roads. The cycle does not include amber. Supervisory lamps V, R, Fig. 9, are controlled by a switch R2 stepped by J. Faults, signalling and arrangements for dealing with. Lamp LD, Fig. 9, is lit by the relapse of normally energized relay LA if the line is open or one line is earthed or by the operation of marginal relay M if the line is shortcircuited. All these faults release H, Fig. 8, to bring in the flashing amber signal. The point duty officer may then control the impulse relay H by means of a press-button BS and release switch Bc. Congestion signalling. The point duty officer operates and releases one of the keys N, E, S, O, Fig. 8, according to the road on which congestion occurs. This operates one, both or neither of relays X, Y and starts a stepping switch Ra which proceeds bv interaction of the magnet with W, relays X, Y being held when the switch goes off normal. The contacts of X, Y connect relay K to one, two, three or four contacts of the switch and K operates Ap which sends A.C. impulses over the line to the control station where they are received by P and operate a counting chain 1B-8B which lights a lamp S, N, E, O, corresponding to the operated key. The control officer then makes the requisite adjustments. When the congestion has been cleared, the point duty officer operates key An which terminates the signals. Telephonic communication. The control officer operates key C (contacts 22, 23) whereupon Aq pulls up and connects A.C. to the line for the release period of normally operated relay BA which falls back. At the crossing, relay T responds followed by VA, G, E2 and N, which gives visual and ringing signals. The point duty officer lifts the receiver and relay A1 operates over the switch hook CC and sends back A.C. during the release period of N. At the control station N1 pulls up and lights lamp LA whereupon the officer thereat operates key C to connect up his set. A call from the crossing is set up bv lifting the receiver, whereupon Ap is operated over the switch-hook CC and sends the A.C. calling signal,- which is terminated by the operation of Cp. At the control station, A.C. relay P pulls up and energizes N2 which lights lamp LA. Modified system, Fig. 12 (not shown). This system, which is generally similar to that of Figs. 8 and 9, comprises the following modifications : (1) the cycle includes an amber warning; (2) the lamp relays are controlled by a step-bystep switch responding to the control impulses; (3) the control impulses are sent over the banks of a stepping switch, one bank for each crossing, (4) supervisory impulses are sent back to the control station to light red, amber and green lamps in correspondence with the crossing lamps and (5) the relay chain at the 'control station for responding to congestion signals is replaced by a step-by-step switch.