The situation of “digging up and filling down roads" has been an existing stinging problem in many urban areas for many years. With an original solution, the Labour Hero – Dr. Hoang Duc Thao and his colleagues had an initiative to settle this "problem".

Reasons of digging up the roads

In recent years, the development of urban systems and the process of urbanization in our country have been happened rapidly all over the country. Many of the technical infrastructures in urban areas such as transportation systems, water supply, drainage, lighting, trees, collection and disposal of solid waste ... which have been renovated, upgraded or newly constructed have been developed rapidly contributing to renew face of urban areas, gradually enhancing the quality of urban areas, improving the lives of urban populations, contributing to the poverty alleviation and the creation of a foundation for sustainable urban development.

However, the construction, installation and operation of infrastructure projects on roads have been inadequate. The installation of the lines (cables, communication cables, fiber optic ...), pipelines (pipelines of water supply, drainage ...) underground roads or pavements separately is a fairly common method at our urban areas. Although this method is simple, low cost but it will be only suitable if there are not many lines and pipelines.

Real situation of laying the systems of urban infrastructure underground

Moreover, the disadvantages of these works are difficult to manage; the roads and pavements are often excavated and filled down for repair, renovation, operation and maintenance. In addition, because there is no unity among the construction units, each work (cable, water, lighting, information ...) is managed by different units, it is difficult to construct new projects and there are regular incidents on the constructed roads due to not knowing the exact location.

There are many roads which have just been filled down by one unit and then excavated by the other unit. This worsens the urban landscape, causes dust, dirt, environmental pollution and obstructing traffic.... These affect the lives of people much and cost for the preparation of the investment project (survey, design of project...) due to coincidence, overlap, repeat of the work that each investor has to invest the same.

These types of underground projects are now interested in the new urban areas but not concentrating in the technical boxes, only arranging separately. The asynchronous investment situation of above mentioned infrastructure projects has brought about bad effects to be active in the project schedule and project quality, wasted of time, money, effort and caused difficulties in the management of urban development investment.

Economic development associated with the development of urban transport infrastructure, in which, the works of urban infrastructure is an integral part of urban traffic. Therefore, we cannot build a modern urban area without a complete and synchronous construction of underground system of urban infrastructure. This problem has been institutionalized by the Law on Urban Planning of the XII National Assembly.

The interlacing network is quite common in the centers of big cities

Currently, not only in the big cities such as Hanoi, Ho Chi Minh but also in other provinces and cities of the country, most of the networks of high voltage, medium voltage and low voltage are aerial; and all types of "mistletoe" as telephone cables, fiber optic for internet "being installed” with a dizzy speed, the cobweb system of grid and communication cables of these cities not only worsens the urban landscape but also causes unsafe for people. Therefore, the "aerial garbage collection" for returning beautiful landscapes to the cities is no longer a "private task" of electrical industry.

The system of electrical poles is not strictly managed, so some enterprises “have illicitly wired for electricity” in an arbitrary way without getting any license. This means they can wire for electricity at any places where being convenient for them, they ties interlacing wires as a "cobweb" as long as reaching their purposes. The “hurry illicit wiring” of the cables which is not under any order or standard not only worsens the urban landscape but also causes unsafe for residents living below the cables. There have been many accidents on the roads due to cables have been broken and hung over in the air. This is a "trap" for passers.

Settling of this “problem” with the precast technical trenches

Facing these inadequacies, Dr. Hoang Duc Thao – General Director of Ba Ria-Vung Tau Urban Sewerage and Development Company together with his colleagues implemented the theme of "Research and application of precast reinforced concrete tranches with thin walls for laying infrastructure system in urban areas of Vietnam underground " in order to implement the urban embellishment process towards the civilization, modernization to deploy the synchronous sustainable and useful construction of urban infrastructure system in accordance with the provisions of the Law on urban planning.

The solutions of technical Tuynel, Cable pipe, technical tank and technical trenches are normally used for laying the works of infrastructure in urban areas underground. After analyzing the advantages and disadvantages of the alternatives, Dr. Hoang Duc Thao and his colleagues evaluated: The technical trenches have shown the most remarkable advantages during the investment, construction, operation, repair and maintenance...

The current manufacture and construction of technical trenches in Vietnam can be divided into two categories: on-site constructed technical trenches or precast ones. The on-site constructed technical trenches may include the technical trenches constructed with bricks or concrete poured on site manually. These technical trenches have some limitations such as low productivity due to waiting for a long time, not active in the project schedule, costly in construction and especially not assure the quality: the products are not uniform, concrete grade is low, the products do not guarantee the waterproof, corrosion…

On-site constructed technical trenches

Compared with the on-site constructed technical trenches, the precast ones have the advantages such as quick construction manipulation; the quality is guaranteed by the in-house verification and cost savings due to manufacturing according to the industrial line. These technical trenches can be precast with a part of body and the slap is concreted or the whole of trenches are precast and transported, assembled on site.

However, the technical trenches in the current market: having simple structures, without compartments and used with horizontal support; Ensuring the safe isolation distance among the infrastructure works is very difficult due to the dimensions of trenches are limited by the conditions of urban underground space, many technical infrastructure cannot be arranged at one place; The surface area is not enough to arrange distances according to the norm of each sector…

Dr. Hoang Duc Thao said: “In order to overcome the current situation of frequent digging up and filling down the roads, it is necessary to invest the synchronous upgrading of the technical infrastructure system, especially must lay the works of urban infrastructure underground. The solution is to manufacture the precast reinforced concrete technical trenches with thin walls arranged the suitable compartments to install underground infrastructure systems, ensure the requirements of safe, water-resistant, anti-erosion, anti-corrosion, high bearing capacity and manufacture at low cost.

The solution of Dr. Hoang Duc Thao and his colleagues’ technical trenches

The given technical solution is the design of reinforced concrete technical trenches with thin walls precast into each section and being connected to each other by rebate joints; Each section of trench is divided into several compartments depended on the numbers of underground works which are required for installation at each areas; The cover slab of the trench is reinforced concrete bearing plate, its underside is arranged slots along the slab in order to fix it to the wall and to resist horizontal thrust; the slots contacting slab and trench is inserted high quality cement mortar to ensure being tight, preventing water from outside flowing into the trenches.

 

The solution is deployed in many cities after successful trial in Ba Ria - Vung Tau

From given technical solution, Dr. Hoang Duc Thao and his group of colleagues determined to invest in researching and successfully applied in Ba Ria - Vung Tau, which has contributed to upgrading the system of urban technical infrastructure. Not only in Ba Ria - Vung Tau, this technology has been applied in many cities and provinces in the whole country.

With this research theme, Dr. Hoang Duc Thao and his colleagues were highly appreciated by the World Intellectual Property Organization and Vietnam Fund for Supporting Technological Creations (VIFOTEC). This research works was awarded the first prize of Scientific and Technological Innovation Award of Vietnam by VIFOTEC. At the same time, this research theme also win WIPO award for the best works.