1 GENERAL PROVISIONS
1.1 Scope
This regulation stipulates the mandatory technical requirements and management requirements that must be complied with in the investment, construction, renovation, and upgrading of trench and tunnel works.
1.2 Applicable Entities
This regulation applies to organizations and individuals involved in the investment, construction, renovation, and operation of tunnel and trench works.
1.3 Referenced Documents
The referenced documents below are essential for the application of this regulation. In cases where the referenced documents are amended, supplemented, or replaced, the latest versions shall apply.
QCVN 01:2021/BXD, National Technical Regulation on Construction Planning;
QCVN 02:2022/BXD, National Technical Regulation on Natural Condition Data for Construction;
QCVN 33:2019/BTTTT, National Technical Regulation on Installation of Telecommunications Outside Plant Cable Networks;
QCVN 01:2020/BCT, National Technical Regulation on Electrical Safety.
1.4 Terms and Definitions
In this regulation, the following terms are understood as follows:
1.4.1
Technical Trench
A small-sized underground route structure for installing pipelines, cables, and technical pipelines.
1.4.2
Technical Manhole
A vertical underground structure within the technical trench system, used for installing and connecting telecommunications, power, public lighting cables and wires, water supply pipelines, energy supply pipelines (if any), and reserve supply.
1.4.3
Technical Tunnel
A large-sized underground route structure sufficient to ensure that people can perform the tasks of installing, repairing, and maintaining technical equipment and pipelines.
1.4.4
Technical Connection
The connection between underground technical pipelines, cables, wires, trenches, and technical tunnels with each other.
1.4.5
Underground Technical Pipelines, Cables, Wires
Water supply, energy supply, drainage pipelines, power supply and communication lines constructed underground.
1.4.6
Emergency Exit
A structure that ensures the exit of operating personnel from the technical tunnel to the ground in case of an emergency.
1.4.7
Isolation Compartment
A part of the technical tunnel, with an independent ventilation system, which is a temporary shelter for operating, repairing, and maintenance personnel in case of an emergency.
1.4.8
Control Station
A construction for installing the control and monitoring system for the operation of technical equipment in the technical tunnel.
2 TECHNICAL PROVISIONS
2.1 General Requirements
2.1.1 Trench and tunnel works must conform to the construction planning, urban planning, and specialized planning approved by competent authorities.
2.1.2 The design and construction of trench and tunnel works must consider the impact of natural conditions, the service life of the works, the impact of climate change, and sea level rise. In particular, it must consider:
– Ensuring the load-bearing capacity of the building structure;
– Taking into account the topographic, geological, and hydrological conditions and sea level rise conditions in the area;
– Not affecting adjacent works and other works that the trench and tunnel cross;
– Allowing the application of advanced construction technology;
– Convenient and efficient in construction and operation.
2.1.3 Materials and structures of trench and tunnel works must ensure the requirements of durability, fire safety, water resistance, and stability throughout the service life (lifetime) under the impact of loads and natural environment, meeting the technical requirements according to the selected applicable standards.
2.1.4 The size of the trench and tunnel must ensure the designed functions, safety, convenience during operation, and take into account future growth.
2.1.5 The depth and location of trenches and tunnels must be based on technological characteristics, topographic conditions, engineering geological conditions, and hydrogeological conditions. The depth of the technical infrastructure network and other works that the trench and tunnel cross, as well as the construction methods and loads acting on them, must be considered.
2.1.6 The connection of underground technical infrastructure works with each other and with other underground works must ensure safety, convenience in operation, and meet the technical requirements for the connecting works.
2.1.7 The fire and explosion safety, drainage, lighting, and ventilation systems in trenches and tunnels must ensure convenience during construction, repair, maintenance, and servicing.
2.1.8 In areas affected by mining activities and land subsidence areas, technical measures must be taken to ensure the safety of trenches and tunnels.
2.1.9 Dryness and cleanliness must be ensured in trenches and tunnels.
2.1.10 Trenches and tunnels must have identification marks on the ground surface.
2.1.11 Geotechnical – environmental monitoring, geological environment monitoring, the tunnel works themselves, underground technical infrastructure works, and adjacent works must be carried out during the construction and operation of tunnel works.
2.2 Technical Trench
2.2.1 Structure of Technical Trench
2.2.1.1 A technical trench is structured with: technical manholes, a support system, and separate compartments (if any) for arranging wires, cables, and pipelines.
2.2.1.2 The size and shape of the technical trench must meet the needs (with a 10% reserve) of installing various types and sizes of wires, cables, pipelines, and safety distances between them, complying with the provisions in the regulations for each type of pipeline arranged in the technical trench.
2.2.1.3 The depth of the technical trench is determined based on the following principles:
– Ensuring the load-bearing capacity of the building structure;
– Taking into account the topographic, geological, and hydrological conditions and sea level rise conditions in the area;
– Not affecting adjacent works and other works that the trench crosses;
– Allowing the application of advanced construction technology;
– Convenient and efficient in construction and operation.
2.2.1.4 When arranging a technical trench under the sidewalk, outside the vehicle lane, the edge of the trench must be at least 1.0 m away from the building wall.
2.2.1.5 On branch lines in residential areas, it is allowed to be arranged under the vehicle lane. The lateral distance between the technical trench and urban underground technical infrastructure works not located in the trench or tunnel must comply with the provisions of QCVN 01:2021/BXD.
2.2.1.6 The layout of technical trenches in residential areas must anticipate the possibility of constructing works in stages as well as their expansion and repair.
2.2.1.7 The depth from the top of the trench cover to the sidewalk surface must not be less than 0.3 m, and to the vehicle lane surface must not be less than 0.7 m.
2.2.1.8 The bottom of the technical trench must have a minimum longitudinal slope of 0.1% to ensure drainage and dryness in the technical trench.
2.2.1.9 Technical manholes must be arranged at intersections, turns, and on straight sections of the technical trench with a maximum distance of 100 m.
2.2.2 Wires, Cables, Pipelines in Technical Trench
2.2.2.1 In the technical trench, it is allowed to arrange telecommunications, power and public lighting wires and cables; water supply pipelines; energy supply pipelines. Wires, cables, and pipelines arranged in the technical trench must have identification marks according to current regulations.
2.2.2.2 The arrangement and undergrounding of wires, cables, and pipelines must be based on the following principles:
– Ensuring the connection with the common system of wires, cables, and pipelines of the urban area;
– When combining the arrangement of wires, cables, and pipelines in the technical trench to the subscribers, it must comply with the regulations on shared use of the system of technical manholes and tanks in the local area and relevant specialized regulations;
– The location of wires, cables, pipelines, and the distance between them must be clearly identified so as not to affect each other and must ensure safety throughout the operation process, complying with the provisions in QCVN 01:2020/BCT, QCVN 33:2019/BTTTT and other relevant legal provisions;
– The horizontal arrangement of wires, cables, and pipelines must be suitable with the technical requirements for each type, convenient for operation, management, maintenance, and ensure fire and explosion safety. The distance from the pipeline to the wall of the technical trench must not be less than 0.05 m.
2.2.2.3 Wires, cables, and pipelines in the technical trench must be placed on supports or in separate compartments. The structure of the pipeline supports as well as the contact position between the pipe and the support must ensure durability, stability, safety, and convenience in the management and operation of the system.
2.2.2.4 The distance, size, and number of supports for various types of pipelines and power supply must be suitable with the design of each work and ensure the provisions in 2.2.1. For wires and power cables with different voltages when placed on the same support, there must be partition walls or a distance of 0.05 m.
2.2.2.5 Wires, cables, pipelines, and connection joints in the technical trench must ensure the mechanical, physical, chemical, electrical requirements, moisture-proof, corrosion-resistant properties, and durability in the underground environment.
2.2.2.6 Pipes, pipe lining materials, and coating materials or accessories and parts of the pipeline system must all be suitable for the intended use and maximum operating pressure. The regulations of relevant sectors must be complied with.
2.2.2.7 Measures must be taken to prevent interference to communication lines caused by power lines when arranged together in the technical trench.
2.2.2.8 The minimum vertical clearance between the cantilever supports for wires, cables, and pipelines in the technical trench must ensure:
– Between communications cantilever supports, a minimum of 0.15 m; the distance from the communications cantilever to the power supply support located above, a minimum of 0.2 m;
– The distance from the cantilever support for technical equipment to the roof and bottom of the technical trench, a minimum of 0.15 m;
– The distance from the water supply pipeline or other technical systems and from the power supply cantilever to the roof and bottom of the technical trench, a minimum of 0.2 m.
2.2.3 Technical Manhole
2.2.3.1 The minimum clear dimensions on the plan of the technical manhole in the technical trench system must ensure convenience in operation, with a length not less than 1.5 m, the depth and width of the manhole must be greater than the depth and width of the technical trench by at least 10%.
2.2.3.2 Dryness, cleanliness, convenience for entry and exit, and operation in the technical manhole must be ensured.
2.2.3.3 The surface of the technical manhole cover:
– Must be at the same level as the finished traffic road and sidewalk;
– Must be at least 0.05 m higher than the ground level of the green area;
– Must be at least 0.2 m higher than the ground level in non-built-up areas;
– The technical manhole cover must be able to withstand the impact load in all cases;
– Ensure that solid waste does not fall into the technical manhole.
2.2.3.4 At locations with water collection, at least 02 submersible pumps must be arranged (one working pump, one backup pump).
2.2.3.5 When using a gravity drainage system from the manhole or water collection pit through a pipe or channel, the diameter of the pipe or channel must not be less than 0.2 m, in which the drainage slope from the manhole or water collection pit to the common drainage system is at least 0.5%.
2.3 Technical Tunnels
2.3.1 Structure of technical tunnels
2.3.1.1 Technical tunnels consist of: functional rooms, isolation compartments, control stations, entry or exit and emergency exits, water collection pits, structural details for installing lighting, drainage, ventilation, communication, security signal systems and automatic warning devices in case of fire and explosion incidents.
2.3.1.2 The selection of dimensions, shape and structure of technical tunnels must be based on the following principles:
– Ensure the installation needs of types, sizes of cables, lines, pipes and safe distances between them, complying with regulations in the standards for each type of cable, line, pipe arranged in the technical tunnel;
– Ensure safety, efficiency and convenience in the operation, maintenance and repair of cables, lines, pipes arranged in the technical tunnel;
– Must have provisions for future expansion.
2.3.1.3 The minimum clearance height of technical tunnels is 1.9 m; the minimum clearance width is 1.6 m. The clearance width and height of walkways in technical tunnels must not be less than 0.8 m and 1.8 m.
2.3.1.4 The bottom of technical tunnels must have a minimum longitudinal slope of 0.1% towards the water collection pit, ensuring drainage and dryness in the technical tunnel.
2.3.1.5 Each isolation compartment in the technical tunnel must have an independent ventilation device. The length of each isolation compartment and the location of the isolation compartments must be calculated based on urban construction conditions, technical solutions and master planning.
2.3.1.6 Entry or exit doors must be arranged at intersections and on tunnel routes with a maximum distance of 500 m/door, with a clearance length not less than 1.5 m, a clearance width not less than 1 m. The doors must have ladders to access the technical tunnel.
2.3.1.7 The covers of entry or exit doors of technical tunnels must be designed to eliminate the possibility of water flooding into the tunnel with a probability exceeding the flood level based on historical hydrometeorological, hydrogeological data and sea level rise forecasts.
2.3.1.8 There must be a system of directional and emergency exit signs in the technical tunnel.
2.3.2 Cables, lines, pipes in technical tunnels
2.3.2.1 The arrangement of cables, lines, pipes in technical tunnels must comply with the design documents approved by competent authorities.
2.3.2.2 Telecommunication, power and public lighting cables and lines; water supply pipes; energy supply pipes; drainage pipes (if any) are allowed to be arranged in technical tunnels. Cables, lines, pipes arranged in technical tunnels must have identification marks according to current regulations.
2.3.2.3 The arrangement and undergrounding of cables, lines, pipes in technical tunnels must meet the following requirements:
– Ensure safety for people, the works themselves, adjacent works and related technical infrastructure systems;
– Ensure connection with the common cable, line, pipe system of the city;
– When combining the arrangement of common cables, lines, pipes in technical tunnels, regulations on the shared use of technical conduits and chambers in the area and relevant industry standards must be complied with;
– The positions of cables, lines, pipes and the horizontal distances between them must be clearly determined to avoid mutual interference and must ensure safety throughout the operation process, complying with the provisions of QCVN 01:2020/BCT, QCVN 33:2019/BTTTT and other relevant legal regulations. The clearance distance from pipes to the walls of technical tunnels must not be less than 0.05 m.
2.3.2.4 Cables, lines, pipes in technical tunnels must be placed on supports or in separate compartments. The structure of pipe supports as well as the contact positions between pipes and supports must ensure strength, stability, safety and convenience in the management and operation of the system.
2.3.2.5 The distances, dimensions, and number of supports for various types of pipes and power lines must be in accordance with the design of each works and ensure the provisions in 2.3.1. For different types and voltages of power lines when placed on the same support, there must be partitions or a distance of 0.05 m between them.
2.3.2.6 Cables, lines, pipes, and connecting joints in technical tunnels must ensure mechanical, physical, chemical, electrical, moisture-proof, corrosion-resistant, and durability requirements in underground environments.
2.3.2.7 Pipes, pipe lining materials, coating materials or accessories and parts of the pipeline system must all be suitable for the purpose of use and the maximum operating pressure. Relevant industry standards must be complied with.
2.3.2.8 Measures must be taken to prevent interference to communication lines caused by power lines when arranged together in technical tunnels.
2.3.2.9 The minimum vertical clearance between cantilever supports for cables, lines, pipes in technical tunnels must ensure:
– Between information line cantilever supports, a minimum of 0.15 m; the distance from the information line cantilever to the power line support above, a minimum of 0.2 m;
– The distance from the technical equipment cantilever to the roof and bottom of the technical tunnel, a minimum of 0.15 m;
– The distance from the water pipe support or other technical systems and from the power line cantilever to the roof and bottom of the technical tunnel, a minimum of 0.2 m;
– The distance between power line cantilever supports up to 35 kV, a minimum of 0.25 m.
2.3.2.10 The minimum distance between optical lines and power line systems arranged in technical tunnels must comply with the safe distance regulations in QCVN 01:2020/BCT, QCVN 33:2019/BTTTT.
2.3.2.11 Pipes made of flammable materials in technical tunnels must be placed in separate compartments.
2.3.2.12 It is not allowed to install gas pipes, pipes carrying flammable and combustible substances together with cables in technical tunnels.
2.3.3 Technical requirements for technical tunnels
2.3.3.1 In plan, technical tunnel routes must be prioritized along streets and main traffic axes; they may be placed under sidewalks or under roadways.
2.3.3.2 The minimum horizontal distance between technical tunnels and underground urban technical infrastructure works must comply with QCVN 01:2021/BXD.
2.3.3.3 The depth from the ground surface to the top surface of the technical tunnel roof must ensure safety when subjected to the impact of adjacent works, temporary loads on the ground surface, and in all cases, must not be less than 0.7 m. When placing tunnels deeper than the foundations of adjacent buildings or technical networks, technical measures must be taken to ensure the safety of those works.
2.3.3.4 The angle and intersection position in plan of technical tunnels with other linear works (metro, railway, road, tram, etc.) must not be less than 60°. The distance from the intersection to the equipment of the above works must ensure safety during operation.
2.3.3.5 Technical systems: lighting, ventilation, water supply, drainage, power supply, fire prevention and fighting, emergency exit and operation control systems in technical tunnels must ensure safety, not cause incidents during the construction and operation of the works and must comply with the provisions of the selected applicable standards.
2.3.3.6 The power supply for technical tunnels must be from two independent, separate sources, complying with the provisions of QCVN 01:2020/BCT.
2.3.3.7 It is not allowed to connect other consumers (street lighting, advertising works, commercial works, etc.) to the power grid of technical tunnels.
2.3.3.8 There must be a water collection system flowing by gravity into collection pits, arranged at low positions of the technical tunnel.
2.3.3.9 When using a separate pumping station for the technical tunnel or pumping water from collection pits, at least 02 submersible pumps must be arranged (one working pump, one standby pump).
2.3.3.10 When using a gravity drainage system from the collection pit through pipes or gutters, the pipe or gutter diameter must not be less than 0.2 m; in which the drainage slope from the collection pit to the common drainage system is at least 0.5%.
2.3.3.11 Surface water, groundwater and other liquids must be prevented from entering the technical tunnel works, and anti-corrosion measures must be taken for the technical tunnel.
2.3.3.12 Technical solutions must ensure sanitation and safety standards for workers during construction and operation.
2.3.4 Building structures
2.3.4.1 The structural design of technical tunnel works must take into account the impact of loads, natural factors according to QCVN 02:2022/BXD and the interaction of the works with the surrounding geological environment as well as adjacent works.
2.3.4.2 There must be measures to seal the gap between the outer face of the technical tunnel structure and the excavated tunnel wall, meeting waterproofing requirements according to the selected applicable standards or the approved design brief.
2.3.4.3 When arranging technical tunnels in areas affected by earthquakes, subsidence areas or areas affected by mining activities, measures must be enhanced to stabilize, prevent subsidence, waterproof, and prevent fire and explosion for the technical tunnel structure and the pipes within it.
2.3.4.4 When crossing water obstacles:
– The depth of the technical tunnel section under water must consider the specific conditions of each area, in all cases, must not be less than 0.5 m from the design elevation of the riverbed to the top (roof) of the technical tunnel; within the river channel limits with boat traffic, it must not be less than 1 m;
– The protective layer on the top of the technical tunnel must be reinforced to resist the erosive impact of the water flow;
– The joints between the prefabricated segments of the technical tunnel must ensure waterproofing. Waterproofing materials for joints must be made of elastic materials and have long-term durability.
2.3.5 Ventilation
2.3.5.1 Ventilation of technical tunnels (artificial or natural flow) must consider the impact of climate change. Temperature and wind velocity conditions in technical tunnels must ensure compliance with current regulations on occupational safety and hygiene. The spacing and cross-section of ventilation ducts must be calculated based on the cross-sectional dimensions of the technical tunnel, specific area conditions to ensure safety for repair, maintenance and servicing personnel in the technical tunnel when switching on the ventilation equipment. The spacing between ventilation ducts must not exceed 150 m in all cases, and the cross-section of ventilation ducts must not be less than 0.2 m. Measures must be taken to ensure safety, security and avoid rainwater from entering the technical tunnel.
2.3.5.2 A system for monitoring and checking the content of carbon monoxide (CO), toxic gases, and flammable and explosive gases must be equipped in areas where the technical tunnel route intersects gas-bearing strata and gas pipelines.
2.3.6 Warning signals
2.3.6.1 A warning device system must be installed for the operation of energy supply sources and the presence of toxic gases in the technical tunnel.
2.3.6.2 An automatic fire alarm system must be installed in the technical tunnel.
2.3.6.3 The technical tunnel must be equipped with a security signal system or surveillance camera for the purpose of detecting unauthorized intrusion of violators in the technical tunnel.
2.3.6.4 Warning information and signals must be transmitted to the control station.
2.3.7 Fire safety
Technical tunnels must ensure fire safety in accordance with fire prevention and fighting laws and other relevant legal regulations.
2.4 Maintenance
2.4.1 Technical trenches and tunnels must be periodically maintained or replaced throughout the operation period of the works to ensure their designed functions.
2.4.2 Technical trenches and tunnels must be maintained in accordance with regulations on the maintenance of construction works.
3 IMPLEMENTATION
3.1 Transitional Provisions
3.1.1 For construction investment projects approved before the effective date of this regulation, implementation shall continue in accordance with the regulations at the time of approval; the investment decision maker has the right to choose to apply this regulation.
3.1.2 Construction investment projects approved from the effective date of this regulation shall be implemented in accordance with the provisions of this regulation.
3.2 State management agencies in charge of construction in localities are responsible for organizing the inspection of compliance with this regulation in the formulation, appraisal, approval and management of construction designs.
3.3 The Ministry of Construction is responsible for disseminating and guiding the application of this regulation to relevant entities. During the implementation of this regulation, if there are any problems, all comments should be sent to the Technical Infrastructure Department, Ministry of Construction for guidance and resolution.
