PROBLEM TO BE SOLVED: To maintain the polluted state of air in a tunnel with a crossroad and a junction excellently, and to operate ventilation facilities accurately. ;SOLUTION: In a wind-direction anemometer 3 in a junction tunnel, wind velocity Vr3 in the junction tunnel is measured, and a measured signal is output to a jet-fan operation-number arithmetic means 5 through a switch 7. The arithmetic means 5 checks wind velocity Vr3, a jet-fan operation-number command value NJF* is increased by ΔNJF (number) from a current value when the value of the Vr3 is made lower than a preset value Vr3L, and the value NJF* reduced by ΔNIF (number) from the current value is output to a jet-fan driving device 6 as a new command value when the value of the Vr3 exceeds a preset value Vr3U. When the wind-direction anemometer 3 in the junction tunnel cannot be used by trouble, etc., the switch 7 is turned off and a switch 8 is turned on, and the arithmetic means 5 arithmetically operates the number of jet fans operated by using the arithmetic result of a wind-direction wind-velocity arithmetic means 4 in the junction tunnel.;COPYRIGHT: (C)1998,JPO
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