Highway tunnels are long, enclosed environments with emergency parking bays, vehicular cross passages, pedestrian cross passages, substations, ventilation rooms, firefighting points and communication equipment rooms distributed along the route. When vehicle collisions, fires, equipment failures or emergency calls occur, personnel on site need to contact the control center as quickly as possible, while duty operators must promptly confirm the incident location and notify inspection, maintenance, firefighting and traffic management teams.

Mobile phones can be affected by network coverage, battery level and site conditions, making them unsuitable as the only emergency communication method inside a tunnel. Standard office telephones are also not designed for long-term exposure to humidity, dust, vehicle vibration and continuous noise. Tunnel emergency communication therefore requires fixed industrial telephones connected through a SIP dispatch platform with broadcasting, video surveillance and call recording systems, allowing field calls to enter the control center's incident response workflow directly.

Communication Challenges in Highway Tunnels

Communication points are distributed along the tunnel, often at considerable distances from the control center. After an incident occurs, a caller may be unable to accurately describe the chainage or travel direction, particularly in smoke, power outages or stressful situations. Relying only on verbal descriptions can therefore delay accurate incident identification.

If telephones, broadcasting, video surveillance and fire alarm systems operate independently, duty operators must separately locate the corresponding camera, broadcast zone and contact numbers after receiving an emergency call. Repeatedly switching between different platforms adds operational steps and increases the risk of mismatching field locations.

Tunnel environments also contain continuous noise from ventilation fans, traffic and electromechanical equipment, so ordinary ringing may not always attract attention quickly enough. Equipment rooms, areas associated with hazardous-material vehicles or other locations identified through risk assessment may also require explosion-proof telephones selected according to the applicable hazardous-area classification.

System Components and Access Architecture

A highway tunnel emergency communication system typically consists of field communication terminals, the transmission network, a dispatch platform, broadcasting and alarm equipment, and a recording management system. Telephones installed along the tunnel connect to the control center through industrial Ethernet, a fiber ring network or a dedicated communication network. Dispatchers can answer calls, monitor terminal status and initiate communications from a unified interface.

Each field telephone should be registered with the tunnel name, travel direction, chainage, equipment number and installation location. When a call reaches the dispatch console, the duty operator can immediately identify the calling terminal without spending additional time confirming where the call originated.

Existing analog emergency telephones can be connected to the SIP dispatch system through a voice gateway. Existing equipment does not need to be replaced all at once, and new-build sections and renovation sections can be upgraded in stages according to actual network conditions.

Field Communication Terminal Deployment

Main Tunnel and Emergency Parking Bays

Industrial weatherproof telephones or emergency help phones are suitable for emergency parking bays, tunnel portals and fixed emergency points along the tunnel. Terminals should provide clear identification, simple operation and reliable environmental protection so that drivers or personnel in distress can directly contact the control center.

Vehicular and Pedestrian Cross Passages

Cross passages are used for vehicle diversion, personnel evacuation and emergency rescue. One-touch call terminals can be installed at these locations. After receiving a call, the duty operator can identify the specific cross passage from the terminal name and issue evacuation or standby instructions through the nearby broadcast zone.

Equipment Rooms and Substations

Industrial telephones can be installed in ventilation rooms, pump rooms, substations and communication equipment rooms so that maintenance personnel can contact the control center. The terminal enclosure, protection rating, operating temperature and installation method should be selected according to local humidity, dust and equipment noise.

Special Hazardous Locations

Explosion-proof telephones are not a standard requirement for every location in a highway tunnel. They are only required where a risk assessment confirms the presence of flammable gases, combustible dust or another potentially explosive atmosphere. In such locations, communication terminals should be selected according to the hazardous substance, area classification and temperature group, with the appropriate explosion-proof certification.

Control Rooms and Management Stations

A visual dispatch console is recommended for the tunnel control center, while management stations and duty rooms can use SIP dispatch telephones. Both terminal types can operate within the same numbering system to support routine communication, call transfer and coordination between different operating positions.

Communication Control at the Dispatch Center

The dispatch console displays communication objects by tunnel section, chainage, direction and operating role, while showing terminal states such as online, offline, idle, ringing and in-call. Duty operators can initiate calls by selecting a location directly without memorizing large numbers of telephone numbers.

When a field telephone calls in, the dispatcher can answer directly or transfer the call to inspection, maintenance or management personnel. When several departments need to participate, field personnel, maintenance teams and managers can be connected to the same call, reducing repeated relaying of information.

Emergency help phones can be assigned a higher call priority. If an important line is occupied, authorized personnel may use call intrusion, forced release or monitoring functions where supported by the project configuration. These functions should be restricted to designated roles, and all related operations should be fully recorded.

If a terminal goes offline, the network is interrupted or SIP registration fails, the management platform should generate a prompt or alarm. Maintenance personnel can then arrange inspections according to the equipment number and installation location, preventing field telephones from remaining unavailable for long periods without being detected.

Telephone, Broadcasting and Video Integration

Emergency communication should not end when a telephone call is connected. After receiving an emergency request, the control center needs to use nearby video surveillance to confirm the type of incident, notify the relevant response teams and issue announcements to the appropriate tunnel section.

Taking a vehicle collision inside a tunnel as an example, the response workflow can proceed as follows:

1. A driver or field worker calls the control center using an emergency telephone;

2. The dispatch console displays the tunnel name, travel direction and chainage of the calling telephone;

3. The duty operator answers the call and opens nearby cameras to verify the situation;

4. Inspection, rescue or maintenance teams are notified according to the incident;

5. Nearby broadcast zones are used to instruct approaching vehicles to slow down or stop;

6. If evacuation is required, broadcasting and audible-visual alarm devices near the cross passage are activated;

7. Field feedback, dispatch calls and broadcast operations are stored under the same incident record;

8. After the response is completed, the duty operator confirms closure of the incident.

Telephone locations, camera IDs and broadcast zones should be mapped during system construction. Once this relationship is established, an operator receiving a call can immediately open nearby video and select the corresponding broadcast zone without searching for equipment numbers again.

When integrating with fire alarm systems, traffic incident detection or a tunnel supervisory platform, the interface method, trigger conditions and control permissions should be clearly defined in advance. Actions involving lane closure, personnel evacuation or equipment shutdown should retain a manual confirmation step.

Call Recording and Incident Records

The recording system stores important calls between field telephones, dispatch consoles and management positions, together with information such as caller number, called number, call time, connection status, call duration and operator position.

Management personnel can search records by tunnel name, telephone number, chainage, time or incident ID. If one incident involves several calls, transfers, broadcasts and field updates, the complete response process can be reconstructed chronologically.

Recordings are useful not only for incident review but also for duty inspections, equipment fault tracking and confirmation of instructions. For example, records can show when a maintenance team received a task, whether a traffic warning was issued and when normal tunnel traffic was restored.

Recording retention periods, backup locations, query permissions and export rules should be configured according to operational management requirements. Important records should be protected against deletion or modification by ordinary user accounts to prevent loss of incident documentation.

Reliability and Project Implementation

Highway tunnel communication systems need to operate continuously. Long tunnels, tunnel groups and important traffic corridors can be equipped with redundant dispatch servers, server redundancy, fiber ring networks, UPS power supplies and network operation alarms according to the required management level.

If a core device fails, the standby equipment should take over key communication services as quickly as possible. Numbering data, terminal configurations and recording files should be backed up regularly to prevent a single equipment failure from causing simultaneous loss of system configuration and historical records.

Before formal deployment, terminal registration, voice quality, hotline calling, auto-answer, call transfer, broadcasting, recording and offline alarm functions should be tested. For SIP devices, audio codecs, DTMF transmission, call control and interoperability between equipment from different manufacturers should also be verified.

During field installation, telephone numbers, actual installation locations, chainage labels and platform names should be checked at the same time. Terminal information must remain consistent with actual field locations so that the control center can accurately identify the relevant tunnel area when an alarm occurs.

Operational Results After Deployment

After the system is deployed, fixed emergency call points are available throughout the tunnel, allowing personnel to contact the control center from nearby locations. Duty operators can identify the travel direction and chainage directly from the incoming call information, then open nearby video, contact response teams and issue broadcast announcements.

With centralized terminal status monitoring, offline devices and network abnormalities can be detected promptly. When telephone, broadcast and dispatch records are stored by incident, duty inspections and post-incident reviews no longer depend on manually collecting data from several independent systems.

Becke Telcom can configure industrial weatherproof telephones, explosion-proof telephones, SIP dispatch telephones, dispatch consoles, dispatch servers, voice gateways, recording servers and broadcast terminals according to tunnel length, point distribution, environmental conditions and existing network infrastructure, providing reliable fixed communication for routine tunnel operations, electromechanical maintenance and emergency response.