The system is set to an alternating mode when the tunnel is clear. Entrances A and B will display red and green lights alternately. The alternating time can be configured to 10, 20, or 30 seconds.

(It is recommended to install different signal lights at both ends to prevent vehicles from entering during critical timing and causing accidents.)

When a vehicle approaches Entrance A, the system switches to a dedicated traffic flow mode.
■ Entrance A: Displays a green light with an LED sign showing “One-way traffic. Drive with caution.”
■ Entrance B: Displays a solid red light with an LED sign showing “Oncoming traffic. Do not enter.”

If a single vehicle enters Entrance A and no other vehicles are detected within 50 seconds, the system automatically reverts to the alternating mode (Scenario 1). This ensures that the tunnel is quickly made available for traffic from the other direction.

When a vehicle enters Entrance A, the green light remains active. If another vehicle follows, the system allows for continuous entry. The 50-second green light timer is reset with each new vehicle detection at the entrance.
Calculation: Based on a 350-meter tunnel and a speed of 30 km/h, the green light duration is optimized for safe passage.
Time Limit: The maximum continuous green light time is capped at 3 minutes to prevent long-term congestion.

After 3 minutes of continuous entry from Entrance A, the system initiates a traffic flow change.
Entrance A: Switches to a red light after exactly 3 minutes, prohibiting further entry.
Entrance B: The green light will not be activated until 50 seconds after the last vehicle has been detected at Entrance A. For example, if the last vehicle entered at the 2-minute 50-second mark, Entrance A’s light turns red at 3 minutes, and Entrance B’s light turns green at 3 minutes 40 seconds.
Default Mode: If both entrances are clear after this sequence, the system will switch back to the alternating mode.