Report to ITA

UNDERGROUND CONSTRUCTION IN VIETNAM THE PAST, PRESENT AND FUTURE Bui Duc Chinh1, Nguyen Duc Toan2 Abstract: This paper summerises the history of tunnels and underground structures construction in Vietnam during the XX century, and introduces some ongoing and upcoming projects. The paper also presents a number of problems that need to be paid due attention in the design, construction and management of tunnels in Vietnam in the years to come.

1. Introduction: Underground structures mentioned in this paper include transport tunnels (railway tunnel, roadway tunnel, etc.), municipal underground works (subway system, parking spaces, pedestrian tunnel etc.) and underground system of hydropower plants. This paper will summarize all the underground projects of Vietnam that have been built, are being underway of construction and will be realized in coming years. Some problems on design and construction of underground works in Vietnam are also briefly described.

2. Underground projects already completed or underway: 2.1 Transport tunnels: Before the World War I (1914-1917), Vietnam had no transport tunnel. Underground construction history in Vietnam dates back to the years 1926-1936 under the rule of the French when they begun building the North-South trans-Vietnam railway line. During this period of time, twenty seven (27) railroad tunnel with a total length of 8,409 meters were built using the French design code valid in 1921-1927. These tunnels are to overcome the sea-approaching mountain ridges from the Central province of Quang Binh to Nha Trang city. Generally, all linings consist of stone masonry sidewalls and cast-in-place concrete top crown with a thickness from around 40 to 50 cm. Upon completion of the World War II, Vietnam gained its independence in September 1945, but almost immediately had been striving to survive through the two notable wars, the first was to defend the return of the French which ended with the Dien Bien Phu battle in 1954, the second is known worldwide as American war lasting from 1954 to 1973 1

Ph.D., Head of Underground Structures Department, Institute of Transport Science and Technology (ITST), Hanoi, Vietnam. Web: http://www.itst.gov.vn. Email: [email protected]; or: [email protected] 2 Bridge Engineer, Underground Structures Department, Institute of Transport Science and Technology (ITST), Hanoi, Vietnam. Email: [email protected] ; or: [email protected]

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between the Geneva conference and Paris conference. During this war time, a number of tunnels (12) with a total length of 3,103 meters were built (in 1968-1970) for the railroad lines in the Northern Vietnam that connect Hanoi to three provinces of China, i.e. Guangdong (Guangzhou city), Guangxi (Nanning city) and Yunnan (Kunming city). These tunnels were constructed based on design codes translated from that of Russia and China. Their linings were made of cast-in-situ concrete. Totally, railroad system of Vietnam has 39 tunnels with 11,512 meters in length, all of them were designed for the rail gauge of 1,000 millimeters. The longest tunnel is 1,196.7 meters and the shortest one is only 60.5 meters, both are located in Tuy Hoa district of Phu Yen province. From that time forward, no more railroad tunnel was built. There is only one noticeable repair work in recent time, i.e. the rehabilitation project for 4 railway tunnels around the Hai Van Pass area (Tunnel No. 7, No. 9, No. 10 & No. 13). This project is funded by French government and executed by a joint venture of VSL and Freyssinnet during 2003-2004.

As to roadway tunneling, the following tunnels have been excavated: ™ Doc Xay tunnel (built during 1995 - 1997): It lies on the National Highway No.1A belonging to Hoa Lu district of Ninh Binh province, near Ha Trung district of Thanh Hoa province. This mountain tunnel characterizes itself by a short length of 150 meters and a thick reinforced concrete lining. ™ Deo Ngang tunnel (built during May/2003 - Aug./2004): Deo Ngang tunnel (meaning Transverse Pass) also lies on the National Highway No.1A at around Km 591+550 to 594+399 to connect two provinces of Ha Tinh and Quang Binh. It was designed by the top-ranking Transport Engineering Design Incorporation (TEDI) and constructed by Song Da Construction Incorporation. The main parameters of this mountain tunnel are as follows: 495 meters long, 11.9 m wide, 7.5 m high for two traffic lanes plus a walkway, reinforced concrete lining, application of the NATM construction method. Carriageway inside tunnel is concrete pavement 24 cm thick for the design speed of 80 kilometers per hour. This tunnel will help improve running condition through the Ngang pass, increasing transportation effectiveness, decreasing traffic accidents and detrimental environmental impact. ™ A Roang 1 & A Roang 2 tunnels (Built during Dec./2002 to Aug./2003): Both are located in mountainous region to the west of imperial Hue city, belonging to the Ho Chi Minh Highway. Constructed according to the NATM technology by Truong Son Construction Company (Ministry of Defense), total lenth of the two tunnels is less than 1 km.

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™ Hai Van tunnel (Started Oct/2000, Anticipated Opening to Traffic in May/2005): At this moment (i.e. December 2004), the biggest transport tunnel still under construction is the Hai Van Pass Roadway Tunnel (Hai Van means “Sea Cloud”) on the National Highway No.1A connecting Thua Thien - Hue province and Da Nang city. All civil works were already completed, there remain only some mechanical, electrical and auxiliary items. Opening to traffic is scheduled to be in May 2005. The tunnel system consists of Main Tunnel, Evacuation Tunnel and Ventilation Tunnel, which is designed and constructed on the basis of the NATM philosophy and under financial support of Japanese government. The Main Tunnel has a length of 6,280 m, clearance width of 11.9 m whereas carriageway is 10.0 m, crown radius of 5.95 m, height from finished grade of 7.5 m and opening area of 73.3 m2. The Evacuation Tunnel runs parallel to and center-to-center apart 30 m from Main Tunnel, it serves as an escaping way in case of accident occurred inside the main tunnel. The length of this tunnel is 6,292 m, the width 4.7 m, the height 3.8 m, and opening area 15.5 m2. Longitudinal ventilation system is applied in this project, it includes 32 ceiling jet fans, 3 electrostatic precipitator tunnels and a ventilation tunnel. Total length of the Ventilation Tunnel is 1,910 m; other parameters include 8.2 m wide, 5.3 m high, crown radius 4.1 m and 36.2 m2 opening area. Its cross section is divided into two halves by a reinforced concrete partition center-wall 25 cm thick, one half serves to supply fresh air into Main Tunnel and the other to exhaust waste air out of Main Tunnel.

2.2 Municipal underground works: No municipal underground works such as subway (metro) system, parking garages or pedestrian tunnel have been built in Vietnam until the end of the twenty century.

2.3 Subsurface system of hydroelectric plants: This kind of construction also just has been brought into Vietnam with the breaking ground ceremony of the Hoa Binh hydropower plant in November 1979 (completed in 1994). This plant is located on the Da River (a tributary of Red River), about 76 kilometers to the south-west of Hanoi. Since then, many other hydroelectric plants have been consecutively constructed, such as Yaly, Can Don, Da Nhim, etc. The design and construction of underground tunnel system of these hydroelectric plants had been done according to traditional (conventional) method put forth by Russian builders. Some other big hydropower plants that will be realized in a near future include Son La and Tuyen Quang plants in North-West of Vietnam. At present, Dai Ninh hydroelectric plant is being constructed; its headrace tunnel is being excavated by TBM introduced by Kajima and Kumagai contractors of Japan. -3 -

3. Some projects that will be constructed in future: 3.1 Transport tunnels on National Highways and Railways: ™ A second backbone railway line parallel to the existing trans-Vietnam railway line is under consideration of the government. Unlike the existing unique line which mainly runs along the coastal plain strip next to the Pacific ocean, the new one will go to the west mountainous area (Truong Son range) along the border with Laos and Cambodia. Therefore, a number of mountain tunnels can be predicted. This project is within the general development planning of railroad sector until the year 2020 [1]. ™ Some important tunnels on National Highway No.1A [2]: Together with Doc Xay tunnel, Deo Ngang tunnel (already opened to traffic) and Hai Van Pass Roadway tunnel (nearing completion), some other new mountain tunnels will be excavated on National Highway No.1A in order to ensure safety for exploitation of this artery transport line of the country. They are: ♦ Deo Ca tunnel: Meaning of “Deo Ca” is Big/Main Pass. This mountainous roadway tunnel is situated in a neighboring area of Phu Yen province and Khanh Hoa province, about 520 kilometers from Ho Chi Minh City. Design and plans are being finalized. Anticipated tunnel length and investment is 4,500 meters and 200 millions US dollars, respectively. Ministry of Transport (MoT) of Vietnam determines that this tunnel is one among eight construction projects that must be given first priority to call for foreign capital investment. ♦ A mountainous roadway tunnel from Hien district to Thanh My of Quang Nam province in Central Vietnam may be constructed in 2005 3.2 Underground works that will be constructed in big cities: 3.2.1 Hanoi city: ™ Underground works at intersections: According to the transport development planning of Hanoi to the year 2020, on the city's roadway traffic network, in addition to National Highways and radial motorways, 4 new belt rings and 17 main municipal road axes will be built. In order to ensure smooth flow of increasing traffic on the city's roadway traffic network, it is necessary to consider for improvement and new construction of 53 spatial (multi-level) intersections on the above-mentioned new belt rings and main municipal road axes. One of the effective solutions in constructing intersections is to use underground structures below them. In some main projects that are ongoing, construction of pedestrian tunnels at some crossroads such as Nga Tu Vong, Kim Lien and Nga Tu So etc., can be taken as examples. -4 -

™ River-crossing underground projects: According to the adjustment of general development planning of Hanoi to the year 2020 [3], the capital city will be mainly enlarged to the North-West and South-West directions, taking Red River as a symmetric axis. Therefore, the construction of river crossings are becoming an urgent problem. Apart from the construction of some big bridges such as Thanh Tri bridge, Nhat Tan bridge…, a river-crossing tunnel project beneath the Red River has also been proposed, and in future some other river-crossing tunnel proposals can be easily anticipated. ™ Subway (metro) system: According to the general development planning of Hanoi to the year 2020 [4], besides the roadway traffic network there will be also a railway traffic network. Plans to the year 2020 of the new network divide the construction process of the municipal railway system into three stages. Stage 1 (from 2004 to 2010) will build total 46.10 km with 16.45 km going underground and 21 subsurface stations. Stage 2 (from 2010 to 2020) will build total 66.33 km with 5.25 km going underground and 7 subsurface stations. Stage 3 (after 2020) will build more 114.89 km with 9.0 km going underground.

3.2.2 Big cities in Central Vietnam: ™ Hue city: An underground roadway tunnel crossing Huong (Perfume) river is being under study. The proposed tunnel will connect the Dai Noi zone (Royal Palace) on the north riverbank with city's central area on the south riverbank, and it is anticipated to be built around 2005-2006. ™ Da Nang city: Construction of the first pedestrian tunnel in this important central city is also under preparation. The tunnel location is proposed to link the Da Nang Supermarket with the city Park namely 29/3 (29th March). With a size of 6 m wide and 4 m high, this pedestrian tunnel can adopt a volume of 4,200 participations per hour. 3.2.3 Ho Chi Minh city: ™ Underground works at intersections: According to the development planning of transport sector of Ho Chi Minh City to the year 2020 [7], the city's road network will have 1210 intersections, out of that there are 320 important intersections on 75 main streets and gateway traffic roads. At present, hundreds of road junctions are being under overloaded condition. To deal with this matter, the most effective measure would be using tunnels to intersect underground. Ho Chi Minh City has already drawn up a project to transform 4 existing same-level intersections into multi-level ones by means of underground tunnel, including: ♦ Intersection of Nam Ky Khoi Nghia street (Uprising South Vietnam) and Ly

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Chinh Thang street ♦ Intersection of Dien Bien Phu street and Hai Ba Trung street ♦ Intersection of Xo Viet Nghe Tinh street and Cach Mang Thang Tam (August Revolution) street ♦ Intersection at Quang truong Dan chu (Democracy Square) ™ River-crossing underground projects: Ho Chi Minh City typifies the topographical characteristics of Mekong delta with many rivers and canals. In order to preserve these unique waterways and natural environment, many river crossings are necessary [6]. As for Saigon river only, on the section of river flowing through the inner city districts it is planned to construct 10 new bridges with an average length of 1,800 m for each. The problem would become unsolvable if the bridges have to span over the densely populated riverbanks. Land acquisition (site clearance) often costs a huge amount of investment and it is very difficult to keep the existing architectural scenery. In this case a river crossing by means of underground tunnel beneath the riverbed may resolve the matter. According to the plan, at the end of this year the City will begin construction of Thu Thiem immersed tunnel under the Saigon river as well as associated roadways. This tunnel belongs to the Contract Package No.4 of the East - West Boulevard Construction Project, which has a length of about 22 kilometers going through 6 districts and connecting the city center with the new Thu Thiem urban area, with total expenses of over 600 millions USD funded by ODA loans. The most appropriate location to cross Saigon river and link the city center with the new Thu Thiem urban area was selected to be at the end of Ham Nghi street, it is one among 10 advantageous crossing points. The Project had many structure options between various types of bridges and underground tunnels, finally the immersed tunnel option was chosen. Total length of the tunnel option is 1,774 meters (approach roads: 551 m, tunnel section with cover plate: 851 m, immersed tunnel section: 372 m). Tunnel height is 9.05 m, tunnel width is 22.80 m (outer dimensions), providing 4 traffic lanes. Total expenses of about 121.5 millions USD for tunnel construction is estimated. ™ Subway (metro) system: In the world, metro has been built at big cities having more than one millions inhabitants and traffic volume of 12,000 to 60,000 participations per hour (in one direction during the rush hour). Although preliminary investment is large, metro is much more economical compared to other technical solutions considering the same passenger-carrying capacity. Ho Chi Minh City has established a pre-feasibility plan for its municipal transport network based on the iron-wheel means, which incorporates a closed subway system. In the year 2000, the JTCA and TEDI South have jointly organized a workshop on strategies for developing metro in Ho Chi Minh City [8,9]. The workshop provided

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a relatively complete planning on the iron-wheel transport system of Ho Chi Minh City. It combines the iron-wheel transport running on the surface near to city center and its periphery with the subway system going underground the city's existing and new center areas. The combination plan is being finalized and would be brought into construction in a near future. Several main lines which can be expected include the ones from Ben Thanh to Tan Son Nhat with 11 km long, Ben Thanh - An Lac 15 km long, Ben Thanh - Thu Thiem, Ben Thanh - Nam Sai Gon, etc. ™ Underground parking garages, utilities tunnels and other technical underground lines: Recently Ho Chi Minh City has scheduled to construct a number of underground parking spaces, commercial services and public sanitations etc. In some large road construction projects within the new urban areas such as at Thu Thiem zone and District No. 2, underground tunnel systems running below sidewalks have been used to contain cables and technical pipes. ♦ Underground parking garage at Tao Dan Park: The underground space will be used for car parking, the upper space will be used as a football ground (stadium). This garage will be built at the corner of Huyen Tran Cong Chua road where it crosses Nguyen Du street. A four-storey basement is located in an area of 910 square meters, where three storeys will provide parking for 800 cars and the remaining storey functions as a service and commercial center. Upon completion of the parking garage, ground surface will be returned to stadium construction party. This project is implemented in the form of BOT in 30 years. Total investment is estimated at about 140 billions VND. ♦ Tan Tao pedestrian tunnel: The purpose of this pedestrian tunnel is to provide a safe underground path for the workers in the Tan Tao industrial zone instead of having to cross through National Highway No.1A. Its construction is planned to start in October 2004. Tan Tao pedestrian tunnel will link the Tan Tao industrial zone to the Pouyuen Vietnam Joint Stock Ltd. The concrete lining tunnel is designed for two-wheeled vehicles and pedestrians with following work items: main tunnel section, approach tunnel section, staircases, two-way traffic pavement and other facilities; investment may cost more than 27 billions VND. 4. Some problems on design, construction and management of transport underground works in Vietnam: 4.1 Problems on design: In the first years of the XX century, tunnel construction had been carried out mainly by the French on the trans-Vietnam railway line within the Central Vietnam. General feature of these railway tunnels is that they were designed according to the old French -7 -

specifications for the rail gauge of 1,000 millimeters. Calculations were made in accordance with traditional methods of Soil Mechanics and Rock Mechanics in the early years of the 20th century. From mid 1960s to beginning of 1980s, the design of tunnels in Vietnam was mainly for the sake of additional tunnels construction on the railway lines in Northern Vietnam, and was in principle based on the Specifications/Standards of China and USSR. These Specifications were set up on the basis of the research results of Soil Mechanics and Rock Mechanics in mid of 20th century. In recent years, in line with the integration process of the country to the world, Vietnamese engineers have already approached to new design methods [10]. Loadings (earth pressures) acting on the tunnel linings used by these methods are not supposed in advance, but they are determined by solving the problem of soil/structure interaction with support of Finite Element Method (FEM). Design engineers have familiarized themselves with the use of geotechnical software such as SAGE CRISP of The Crisp Consortium Ltd, PLAXIS of PLAXIS BV Ltd., module SIGMA in GEOSLOPE program of GEOSLOPE-International Ltd., and MISES3 program of TDV Co. used for the NATM method, etc. Especially, with the assistance of Japanese side through a technology transfer plan at the Hai Van Pass Construction Project, Vietnamese engineers have successfully designed and constructed the Deo Ngang (Transverse Pass) tunnel by themselves. It is well known that an underground structure is a combination of various systems. In addition to the main structural part which involves professionals expert in geotechnics and structural analysis, underground works also demand the involvement of professionals of many other fields relating to design and installation of auxiliary systems such as electrical, mechanical, ventilation, etc.

4.2 Problems on construction: As stated above, during the early period all the tunnels on the trans-Vietnam railway route have been built by the French using manpower and simple tools, the linings are made of cast-in-place plain concrete in combination with stone masonry. Tunnel length is relatively short and facilities are very simple. During the next period between the decades 1960 and 1980, the construction of additional tunnels in Northern railway lines as well as construction of underground tunnel system at Hoa Binh hydropower plant have essentially followed the USSR technology, where the lining is considered as a main load-carrying member resulting in a heavy and costly structure. In the last years of 20th century, advanced construction technologies have been

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transferred to Vietnam, mainly through Hai Van Pass Project. One of such technologies is NATM method for construction of mountain tunnels. Then Vietnamese tunnel builders have effectively applied NATM in construction of Deo Ngang tunnel. However, more complicated problems concerning construction of urban underground structures in soft soil conditions of Hanoi and Ho Chi Minh City are posing many new challenges.

4.3 Problems on management: Railway tunnels in Vietnam all had been constructed by manpower in the past, the quality of materials and workmanship was not so high, furthermore, after a long service time without a high-standard and consistent maintenance/repair system, nowadays they are holding out their function in a rather bad condition and can affect normal train running at any time. Recently-built or forthcoming roadway tunnels with modern technologies almost have complicated equipment systems such as ventilation, lighting, power supply, SCADA etc. which require appropriate management procedures. This is also a significant challenge to Vietnamese tunneling industry.

5. For conclusion: Though with a young professional forces which just acquired modern technologies (NATM) in a short period of time, Vietnamese tunnel builders have gradually mastered some advanced tunneling techniques and made contributions to successful construction of modern transport tunnels. In the face of new tasks on underground construction, especially urban underground works, much effort of the Vietnamese tunnel builders should be made. Vietnam has newly become a National Member of ITA-AITES, therefore much support in many aspects ranging from experiences introduction and education/training to information/activity exchange from ITA-AITES side is very needed to facilitate the smooth incorporation of Vietnam into the ITA-AITES processes.

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REFERENCES [1]. Decision No. 06/2002/QD-TTg dated 07/Jan./2002 of Government's Prime Minister on the approval of the General Development Planning for Vietnamese Railway Transport Branch to the year 2020. [2]. Decision No. 162/2002/QD-TTg dated 15/Nov./2002 of Government's Prime Minister on the approval of the Development Planning for Vietnamese Roadway Transport Branch to the year 2020. [3]. Decision No. 108/1998/QD-TTg dated 20/Jun./1998 of Government's Prime Minister on the approval of the Adjustment of General Planning for Hanoi City to the year 2020. [4]. Transport Development Planning of Hanoi City to the year 2020. [5]. Development Planning for Public Transportation of Hanoi City to the year 2010 and 2020. [6]. Decision of Government's Prime Minister on the approval of the General Planning of Ho Chi Minh City to the year 2020. [7]. Transport Development Planning of Ho Chi Minh City to the year 2020. [8]. Development Planning for Public Transportation of Ho Chi Minh City to the year 2010 and 2020. [9]. Iron-Wheel Transport Planning of Ho Chi Minh City and Neighboring Region to the year 2020 and the following years. [10]. Bui Duc Chinh, Nguyen Thai Khanh (2004), “On the application of finite element method in calculating of underground structures”, Report at the Scientific Conference of the Institute of Transport Science and Technology (ITST), October 2004.

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