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A decrease from programme II to programme I takes place under similarconditions and with the associated n 4 knob.Hogalidsgatan is similarly equipped with three programmes. So far thefollowing settings have been found suitable:Maximum times onprogramme Iprogramme IIprogramme 111Langholmsgatan(phase A)20 sees.30 sees.50 sees.Hogalidsgatan(phase /))12.5 sees.17.5 sees.25 sees.Number of maximum times takenout by the traffic in sequencen, (I-» II)n, (II -* III)Number of maximum times not takenout by the traffic in sequencen 3 (III—> II) 3n, C11 —* I > 3When the programme selectors are switched off. the installation functionsas an ordinary vehicle-controlled system with maximum times that can beset separately and that are entirely distinct from the maximum times forprogrammes I, II and III.Fig. 3Control cabinetx7714On the left of the left-hand photograph is thecontrol and indicating panel on which differentforms of operation can be set and indicationsof vehicle impulses etc. can be read;in the centre are the maximum time selectors.The latter, shown in enlargement (right), areused for setting the different programmes betweenwhich the system automatically changesso as to adapt the signals as required by thecurrent traffic situation.To arrive at proper settings of the eight n knobs, as also of the maximumknobs, naturally requires a careful study of the traffic. The aim is to selectvalues which cause the signals to follow programme I at nighttime, programmeIII during peak hours, and programme II at other times.Experience gained hitherto has shown that the requirements have beensatisfied. At midday, for example, it may be noticed that programme II alternateswith programme I on Hogalidsgatan, while at the same time programmeIII alternates with programme II on Langholmsgatan. At night programme Iusually occurs on Hogalidsgatan, and programme I or on some occasionsprogramme II on Langholmsgatan.26