Standards for communications systems for expressways in Vietnam

Hello, the editorial board would like to answer as follows:

1. What is a communications systems for expressways?

Communications systems for expressways is a system of equipment and applications of advanced science and technology to carry out communication between departments involved in highway management and operation and with traffic participants on the highway.

2. Principles for building a communication system in Vietnam

National Technical Standard TCVN 12191:2018 stipulates the principles for building communication systems on highways as follows:

- The communication system on the highway needs to be designed to be interconnected throughout the system to ensure internal communication connections between the Traffic Management and Operations Center with stations, service areas, and mobile vehicles. The system must allow any terminal in the system to make calls to external telephone numbers over the public switched telephone network (PSTN).

- The coverage area of the land mobile radio communication system needs to cover all highway works including the Road Traffic Management Center, toll booth area, service area, parking lot, and other areas along the expressway.

- The communication system needs to meet the following specific requirements:

+ The capacity is large enough to serve all highway projects, with redundancy to ensure a high level of readiness for system expansion and upgrading and external communication connections.

+ Using modern technology, designed in a modular style with a compact structure, capable of responding to changes in frequency and technology.

+ Hving simple operation.

+ Highly stable, providing the best voice and data communication capabilities, capable of communicating quickly, instantly, and smoothly, not depending on any other public communication network.

+ Need to operate with good quality without being affected by any type of interference from any other device information system.

+ Highly confidential, ensuring the safety of information transmitted throughout the system.

+ There is a backup configuration, ensuring continuous communication throughout the system in case of an incident.

+ Ensuring technical requirements on electromagnetic compatibility according to current standards.

+ Ensuring requirements for electrical safety, fire safety, protection against overvoltage, lightning, and lightning shock.

+ There is a tool to monitor the operation of devices. Errors in equipment will be detected and notified promptly through the warning system. During error repair, it is necessary to have backup equipment that operates well so as not to interrupt the operation of the communication system.

+ Equipment for the communication system must be highly durable and ensure quality according to current standards.

+ Frequencies and equipment used for communication systems must be licensed according to current regulations.

+ Not affecting the operation of other information systems on the highway.

3. Technical requirements for communications systems for expressways in Vietnam

3.1 Emergency telephone system

-  Function

The emergency telephone system is used for the purpose of receiving reports of accidents and incidents on the highway from individuals and organizations, operating 24/7. Once a call is established, if there is no answer within 10 seconds, a message will be logged, indicating that the call has been received and will be answered immediately.

The emergency telephone system is composed of two parts:

+ A system of signs indicating emergency phone numbers is along the road, and emergency phone booths are arranged along the highway. Emergency telephone booths are not required to be installed on highways.

+ Telephone to receive emergency calls at the Road Traffic Management Center to collect and process information to ensure that when accidents and incidents occur, rescue work will be deployed immediately and information coordinated quickly with road patrol, traffic police, and medical forces.

3.2 Signs indicating emergency phone numbers

Signs indicating emergency phone numbers are installed on both sides of the highway, with dimensions and installation locations according to regulations on road signs on highways. The installation distance between signposts is 500 m. Instructional information on the sign must include an emergency phone number and a sign placement procedure so that the reporter can easily locate the location on the highway.

3.3 Ground mobile radio communication system

- Operating mode

The ground mobile radio communication system is used for the purpose of connecting professional vehicles and mobile objects on highways. A land mobile radio communication system whose configuration may include: Mobile radio terminals - radios, signal repeaters, radio communication base stations, central controllers, and other system equipment components. Depending on the required communication distance between functional units equipped with mobile radio terminals on the highway, the system can be designed to operate in one of the following basic modes:

+ Direct mode operation (DMO)

Direct mode allows communication between mobile radio terminals without using network infrastructure. The maximum communication distance between two mobile radio terminals is no more than 3 km; in urban areas, it is no more than 2 km. In direct mode, mobile radio terminals can operate in point-to-point (individual call between two terminals) or point-to-multipoint configurations (group call between terminals). For radio communication between functional departments with a distance greater than 2 km, it is necessary to use a signal repeater (with an antenna installed in an elevated position). The direct-mode repeater (DM-REP) rebroadcasts the signal to enable communication over longer distances.

+ Operate in trunk mode (TMO)

Radio trunking mode uses digital trunking to allow simultaneous transmission of both voice and data based on the network infrastructure, increase coverage for the entire highway area, and use channels effectively with a multi-channel system for multiple mobile radio terminals.

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(According to National Technical Standard TCVN 12191:2018)

Best regards!

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