Tunnel ancillary facilities refer to all kinds of facilities and equipment that need to be built in tunnel construction and operation, including but not limited to the following aspects: 1. Lighting facilities: The tunnel must have good lighting facilities to ensure traffic safety. Lighting facilities generally use high-intensity fluorescent lamps, xenon lamps, light-emitting diodes, etc. Ensure that vehicles can see the road conditions, road signs and other vehicles clearly when driving in the tunnel.

2. Ventilation system: The exhaust gas emitted by vehicles in the tunnel will reduce the oxygen concentration in the air, and exposure to this environment for a long time will cause danger to human body. Therefore, it is necessary to establish a ventilation system in the tunnel. Ventilation system is divided into natural ventilation, mechanical ventilation and mixed ventilation. Ventilation equipment usually includes fans, range hoods, ventilation pipes and radiators.

3. Drainage facilities: Drainage facilities inside the tunnel are very important, which can effectively reduce rainwater accumulation and prevent flooding. Drainage system is generally divided into valley drainage and pipeline drainage. Valley drainage is to collect the seepage water from the high trough, and then discharge it to the lower drainage ditch by using the inclined road surface. Pipeline drainage is to drain the leakage water to ditches or collecting wells outside the tunnel through well pipes or drainage pipes.

4. Fire fighting facilities: The safety and disaster risk of the tunnel must be considered during the tunnel construction, so it is particularly necessary to set up fire fighting facilities in the tunnel. Fire control facilities include fire alarm system, fire extinguisher, fire hydrant, fire shutter door, smoke detector, etc. In order to take timely measures to ensure traffic safety in case of fire and other emergencies.

5. Monitoring facilities: In order to know the status and operation of the tunnel, a real-time monitoring system should be installed in the tunnel. Monitoring facilities include road lighting, video monitoring, traffic flow monitoring and air quality monitoring. These facilities can monitor the situation inside the tunnel in real time through the linkage of various sensors and controllers, and make early warning and maintenance in time.

Tunnel ancillary facilities play a vital role in the safety and operation of the tunnel, so we must attach great importance to the construction and maintenance of these facilities in the process of tunnel construction and operation.