Issue 4 September Driving Through Complexity

Transcription

1 Issue 4 September 2014 Driving Through Complexity

2 140 Mechanical PLATFORM Gap Fillers to be Installed for SCL mtr projects facts & figures 122 PAirs of systems interfaces on a typical MTR project 100+ temporary traffic stages for Whampoa station construction Tunnel Boring Machines Non-traffic hours per day for working around operating railway ( hrs) 2300 Automatic Platform Gates to be Installed for SCL DRILL- AND-BLAST 52for 5 new lines of tunnel ALIGNMENT 52kilometres km km km km Tunnel Boring Machines CUT-AND- COVER Immersed Tube

3 02 Foreword by Acting Chief Executive Officer PAGE 29 Putting Theory into Practice September 2014 ISSUE 4 CONTENTS 03 Message from Projects Director PAGE 05 Conquering the Underground 06 Driving Through Complexity 12 The Sensitive Application of Drill-and- Blast Excavation PAGE 19 Complex Systems 20 Designing and Managing Traffic around Sites 24 The Dynamics of Interface Management 30 Admiralty Station: Engineering Challenges to Create a Major Transport Hub 36 Preserving our Heritage, Progressing for the Future 42 Upgrading Operating Lines for Future Railway Services 46 Building an Architecturally Inspired High-Speed Rail Terminus for Hong Kong Editorial Board Members Danal Blessis Patrick Cheng Mona Lam Lesly Leung Patrick Lun Samantha Siu Maggie So P H Tang Paul Tsui Editor Angela Tam, Insitu Publishing Limited Creative Director Ian Yap, Toppan Vite Limited Project Manager Billy Tung, Toppan Vite Limited Photographer Johnny Tung The MTR Projects Journal is published by Insitu Publishing Limited on behalf of the MTR Corporation Limited. ISSN:

4 foreword by Acting Chief Executive Officer foreword by Acting Chief Executive Officer The MTR Corporation is working hard to make Hong Kong s railway network better than ever, connecting to places never served before, using new and advanced methods to construct in highly developed areas, and enhancing our network integration to improve customer journeys. The current portfolio of expansion projects will bring the first high-speed rail services to the city. Another first will be a medium rail, automated train operation South Island Line (East) that will join our urban rail network. In parallel, we are renewing the oldest part of our system, the East Rail Line, to form the Shatin to Central Link s North South Line, which will create our fourth rail harbour crossing. Designing, constructing and operating the MTR in Hong Kong has never been easy, but it has always been rewarding. Now in our 35th year of operation, we have faced challenges from the outset in getting stakeholder buy-in for each new line, in achieving cost and programme targets, and in identifying and mitigating risks. The results have always provided welcome railway services that, combined, form a public transportation backbone that is the envy of the world. Each project we have undertaken through the years has had its unique set of complexities. Implementing the current programme of five major projects in short succession is perhaps the greatest challenge we have faced. But we are driving through these complexities diligently and persistently to ensure we deliver the new railway services that Hong Kong needs for its future growth and prosperity. We are nearing the completion of the first of our five major projects, the West Island Line, which will extend the Island Line into Hong Kong Island s vibrant Western District. As we do this, we are redoubling our focus on the core activities that will enable us to meet our customers increasing expectations while deliver- ing our new Hong Kong rail projects in a safe and timely manner. The experiences we gain and the continuous improvements we make every day prepare us to meet the greater challenges of the future. I hope the stories in this issue of The MTR Projects Journal will demonstrate our ongoing commitment to driving through complexity with positive solutions that achieve desired results. This is the work that our engineers, management and staff thrive on. Lincoln Leong Acting Chief Executive Officer, MTR Corporation 02 The MTR Projects Journal

5 message FROM projects director message FROM projects director Solving complex problems is nothing new to engineers. In fact, this is what engineers do everyday solving problems by applying science and technology to create an improved society for current and future generations. In this issue of The MTR Projects Journal, we focus on how we are applying engineering and project management techniques in solving some of the interesting technical complexities associated with the current railway projects we are delivering for Hong Kong. We are building MTR s largest railway station the West Kowloon Terminus for the Express Rail Link in highly complex ground conditions, with a dam separating the site from the sea. The end product will not only change the state of travel between Hong Kong, the Pearl River Delta region, and major cities on the Mainland of China; it will create a new landmark with open green spaces surrounding an architecturally inspired structure. At Admiralty we are installing extensive support structures beneath the existing operating tunnels to enable the delicate excavation for the future South Island Line (East) and Shatin to Central Link. This will create our largest hub connecting four urban rail lines in the heart of the central business district. Along the busy corridor formed by To Kwa Wan and Ma Tau Wai Roads in Kowloon City, the construction of the Shatin to Central Link requires extensive diversion of traffic and utilities as well as preservation of ancient historical artefacts recently discovered. Completion of these works will bring direct train services between the eastern and western New Territories, via the centre of Kowloon, and ease congestion on the existing cross-harbour routes. At this juncture in our multi-project expansion, we are addressing issues involving tight programmes and cost increases among several of the projects. Our project teams are driving through these complexities with determination to address the challenges and deliver our new railways with the high standards of safety and quality that we all have come to expect. We are doing this by focusing on positive solutions that address complex situations. While projects always come with uncertainties and challenges, we tackle these with a can-do spirit. Our teams, partnering with our consultants and contractors, have the combined expertise and ingenuity to achieve the results we all desire bringing our exciting railway expansion programme to fruition. T C Chew Projects Director, MTR Corporation The MTR Projects Journal 03

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7 Conquering the Underground Driving through complexity The sensitive application of drill-and-blast excavation The MTR Projects Journal 05

8 Driving through complexity Tunnel boring machine breakthrough in urban Kowloon section of Express Rail Link Driving through complexity Mechanised tunnelling minimises disruption in busy districts but must tackle various underground challenges Imagine building a mass transit system in Hong Kong by excavating open pits. In a city as packed with people and traffic as Hong Kong, the idea is unlikely to be welcomed. Mechanised tunnelling techniques, however, have enabled the MTR Corporation to build running tunnels underneath some of the busiest districts in town whilst minimising disruption to surface activities. The use of tunnel boring machines (TBMs) is one of three common methods for excavating tunnels, the other two being drill-and-blast and cut-and-cover. Where there is a long stretch of running tunnels in similar ground conditions, TBM tunnelling is the preferred method because it does not involve the use of explosives that may cause noise and vibration near sensitive receivers in built-up areas nor does it require disruptive open-ground excavation. TBM tunnelling is also efficient. A TBM weighing more than a thousand tons and measuring 6-9m in diameter is equipped to multitask, excavating in front while simultaneously installing and grouting a precast segmental lining behind. Over the years, we have built on our knowledge of Hong Kong s geology in order to make the best use of sophisticated TBMs, of which 16 are being deployed for the construction of 15 km of twin-bore tunnels for West Island Line (WIL), Express Rail Link (XRL) and Shatin to Central Link (SCL). This knowledge is reflected in the Express Rail Link (XRL) project, where we were able to package the contracts to make the best use of resources, with sections of soft or mixed ground excavated by TBMs and sections of hard rock between the mountain ranges of Kam Shan, Tai Mo Shan and Kai Kung Leng being excavated by the drill-and-blast method. Slurry vs EPB TBMs Two types of TBMs are being used on our projects: slurry TBMs and earth pressure balanced (EPB) TBMs. The type of TBM chosen for each tunnel section is a function of ground conditions, risk of encountering obstructions, and the fineness and clay content of the soft soils. 06 The MTR Projects Journal

9 Driving through complexity Tunnel boring machines (TBMs) have enabled the MTR Corporation to build running tunnels underneath some of the busiest districts in town whilst minimising disruption to surface activities. Slurry TBMs are capable of tunnelling through sections of rock but are generally used to excavate in loose sand or gravely ground. A support medium in the form of a water and bentonite mix is used to pressurise the ground face in front of the TBM, enabling a slurry machine to excavate safely in areas with a high water table. EPB TBMs work by using the excavated material itself as the support medium. A paste is formed in the excavation chamber by mixing the excavated soil and groundwater together with additives as necessary to condition the material so that it is capable of forming an impermeable pressure plug in the screw conveyor inside the EPB machine, so called because it requires the pressure of the paste in the excavation chamber to balance the pressure of the surrounding soil and groundwater. The rate at which excavated material is transferred to a belt conveyor by the screw conveyor and the TBM s advance rate are carefully monitored and controlled to ensure the pressure from the paste is maintained. This tunnelling approach, along with the installation and grouting of a precast segmental lining immediately behind the excavation face, minimises groundwater ingress, especially in a place like Hong Kong, which generally has a high water table. In ecologically sensitive areas such as the Mai Po to Ngau Tam Mei section of XRL, this is of utmost importance. The advanced tunnelling machines we have today were still in their infancy at the time the Modified Initial System of the MTR was built in the 1970s. Thanks to new TBM technology, the soft ground that would have been impossible to excavate efficiently 30 years ago can now be tackled, making it possible to plan alignments that serve the public better. TBM tunnelling has also made it possible to thread tunnels for the new projects through crowded spaces without disturbing existing MTR lines, utilities below ground or heavily trafficked areas above ground. For example, about 100m of an SCL tunnel between Hin Keng and Diamond Hill will be constructed in mixed ground with just m separation from the existing Kwun Tong Line tunnel. Elsewhere, the tunnels cross above a major water supplies tunnel with just 6m separation in solid rock. The original Water Supplies Department protection zone precluded drill-and-blast excavation methods. Through working together in reviewing the proposed measures and systems, both WSD and the project team were able to allow blasting to proceed under these circumstances, according to the SCL works programme. Underground obstructions Over the years, the lessons learnt from the projects we have undertaken are continuously reviewed and applied. For example, our experience with underground obstructions along XRL has helped us improve the tendering pro- The MTR Projects Journal 07

10 Driving through complexity Golden Dragon 15 Golden Dragon 16 6 Dia. 9.9m Boring distance 2.9km Length 103m EPB/Slurry Slurry Zhao-jun 1 Zhao-jun 2 Dia. 9.2m Boring distance 5.2km 7 Length 114m EPB/Slurry EPB 6 7 Fan Li Hua Fan Li Hua Dia. 9.2m Boring distance 2.6km Length 80m EPB/Slurry EPB Soeng Ngo Iron Lady Dia. 9.3m Boring distance 9km 9 Length 94m EPB/Slurry Slurry Xi Shi Dia. 6.5m Length 70m Boring distance 0.8km EPB/Slurry Slurry TBM Section Shatin to Central Link TBM Section Express Rail Link TBM Section West Island Line Tunnel Boring Machines will bore approximately 30km of tunnels to form 15km of twin-track tunnels for the current railway expansion programme 08 The MTR Projects Journal

11 Driving through complexity Nu-wa 1 Dia. 7.4m Boring distance 3.5 km Length 96m EPB/Slurry Slurry Mu Gui-ying Dia. 7.4m Boring distance 1.6km 2 Length 95m EPB/Slurry EPB TBM cutterhead is lowered into position in its launching shaft for Express Rail Link southern section tunnel Princess Iron Fan Princess Wencheng 3 Dia. 7.4m Boring distance 3.1km Length 96m EPB/Slurry Slurry Boring distance Under Design 4 1.1km Boring distance Under Design 5 1.0km Full length assembly at manufacturing plant of TBM for tunnel drive from To Kwa Wan to Ma Tau Wai stations, Shatin to Central Link Slurry TBM assembled in its launching shaft for Shatin to Central Link tunnel section near Diamond Hill The MTR Projects Journal 09

12 Driving through complexity break the section of piles that crossed the tunnel alignment. Another challenge involved unknown piles that were discovered during a TBM drive from Nam Cheong to the West Kowloon Terminus. After ground treatment from the surface, workers were sent in front of the TBM to cut the piles, about 40m below ground. This is a project that showed the importance of choosing the right TBM, as the slurry machine enabled workers to access the tunnel face and remove the piles underground. Had a different type of TBM been used, surface access entailing road closures and utility diversions would have been required. Safety and environmental priorities The XRL TBM tunnels are generally located some 40m below ground, enabling them to avoid most building foundations whilst still ensuring the safety of workers operating the TBMs. During interventions to carry out necessary maintenance and repairs of the cutterhead, these machines use compressed air to counter the pressure exerted by groundwater on the cutterhead. Working with compressed air this far below the groundwater table is not unlike taking a deep sea dive and has the same effect on the human body. The workers are effectively working in a hyperbaric environment that requires decompression before they can return to the surface, a process that would take much longer and involve more risk to the workers health should the tunnels be any deeper. Concrete segments for tunnel lining are loaded into the TBM cess by specifying more expensive but versatile slurry TBMs where obstructions may be anticipated. Such obstructions are among the challenges faced by TBM tunnelling. At Nam Cheong about 300 H-piles were removed to make way for the TBM drive through the area. The task called for a new solution as the typical methods for pile removal failed to work: the vibro hammers employed to pull out the H-piles, installed years ago for a future property project, were broken in the process and an attempt to jack up the piles by using powerful hydraulic cylinders also failed. In the course of the operation, it was discovered that the piles could not be completely removed by these methods because they had been bent and twisted when driven into large boulders, which were part of an old seawall. Instead of building a cofferdam for the wholesale removal of the piles, which would have been costly and time-consuming, we collaborated with the contractor in first trialling, then importing, a Japanese pile extraction method called rotator and wedge, which was adapted to the handling of the steel H-piles. Modifications to the method included the development of a cylinder-shaped wedge that could be lowered into a heavy duty steel casing to twist and Where the tunnels are close to the surface, continuous monitoring is carried out to ensure nearby structures are not affected by tunnelling works. This was the case during construction of West Rail near Kowloon Park Drive in Tsim Sha Tsui, where the TBM passed by the foundation of a flyover and was only 5-6m below ground in the vicinity of the former Marine Police Headquarters. The sheer size of the TBMs used for railway tunnelling presents its own challenges. For example, on the Shatin to Central Link (SCL), the delivery of a TBM was complicated by the loading capacity of a bridge over which the 145-ton cutterhead had to be transported. Prior to its delivery to the launch site from a pier on the former Kai Tak runway, a contingency plan was drawn up for the delivery of its parts involving the development of a traffic management plan and coordination with the Police, Transport 10 The MTR Projects Journal

13 Driving through complexity A time for celebration: One of eight TBM breakthroughs for Express Rail Link Department, Highways Department and other stakeholders. An excess weight permit was finally issued by Highways Department after protection work was carried out on the bridge and design calculations were provided to confirm the bridge s ability to support the delivery. Environmental protection is also a priority. As the removal of excavated material by road will have a significant impact on road traffic, the MTR Corportion has taken the initiative to establish a centralised system for removing the excavated material by sea. On XRL, this consists of six barging points and conveyors for transferring the spoil for removal. The slurry used by the slurry TBMs is treated at treatment plants where the excavated material is separated from the bentonite used for the slurry mix before it is transferred back to the excavation face and reused. Our commitment to environmental protection is also reflected in the procurement aspect of our TBM projects. One EPB machine, procured to excavate the Diamond Hill to Kai Tak section of SCL, is a refabricated machine which has previously been used in Rome and Panama. Used TBMs of the right specifications are rarely available at the right time. In this instance, we were able to take advantage of the completion of a project in Panama involving short tunnels. The machine therefore was still relatively new and was modified with a new cutterhead as well as various hydraulic equipment, bearings and electronic equipment ahead of its launch to excavate the two 750m drives for this contract. TBMs deployed in Hong Kong may drive relatively short distances compared to those used on some major infrastructure projects overseas, but the challenges of tunnelling in Hong Kong are often far more complex. Varying ground conditions, congested underground space, embedded obstructions (known and unknown), removal of spoil, and delivery of the huge equipment and parts without overwhelming the busy road network all present problems to be solved. By applying the collective knowledge accumulated over the past two decades by the tunnelling engineers within MTR Corporation together with the latest advances in TBM technology, we are driving through these complexities to deliver the much-needed MTR services to meet the demands for decades to come. Over the years, we have built on our knowledge of Hong Kong s geology in order to make the best use of sophisticated TBMs, of which 16 are being deployed for the construction of 15 km of twin-bore tunnels for West Island Line, Express Rail Link and Shatin to Central Link. Removal of obstructions from front of TBM cutter head The MTR Projects Journal 11

14 treasuring our customers Drilling jumbo drills holes to be charged with explosives for the next tunnel advance for Express Rail Link

15 The sensitive application of drill-and-blast excavation The sensitive application of drill-and-blast excavation Drill-and-blast excavation has been in use long before any MTR railway tunnels were formed in Hong Kong, but it has advanced with modern technology to become a precision method of tunnelling All five of the major railway projects underway in Hong Kong involve tunnelling to form new underground sections of the railways. Drill-and-blast excavation is being employed on all of the projects and accounts for some 26km or about half of the tunnel length being constructed. This method involves the use of explosives inserted into holes drilled by drilling jumbos to blast through rock underground to form spaces for tunnels and stations. Tunnelling method considerations In the early planning stage of a new railway, MTR Corporation s experienced tunnelling engineers consider a wide variety of factors in determining the method of construction to be employed for a certain section of tunnel, whether by drill-and-blast, cut-and-cover, or tunnel boring machine (TBM). We often adopt drill-and-blast excavation where we need to tunnel through long stretches of rock, or where we expect highly variable ground conditions, or where the tunnel is not long enough to justify the large up-front cost of a TBM, or where flexibility is needed that a TBM cannot provide. For shorter tunnels and those with multiple adits, complex configurations and non-standard excavation profiles such as stations with multiple entrances, drill-and-blast excavation is usually fit for purpose and often the most practicable excavation method. It is also the preferred solution for two-way tunnels with a central dividing wall, whose horseshoe shape differs from the circular pattern of a TBM-excavated tunnel. Drill-and-blast excavation is particularly suitable in areas where ground conditions are uncertain or known to be highly variable, as it allows for a more rapid change in the excavation approach. Conversely, TBMs are better suited where they can be designed for specific types of ground conditions and where tunnel excavation needs to be as least disruptive as possible. Therefore, in selecting the best tunnelling method to be employed, our engineers factor in several variables including the known ground conditions, risk factors of unknown ground conditions, length of tunnel, design of the future track configuration, types of stations and entrances, estimated excavation rates for each type, programme time available, and cost. For example, due to the depth of rock cover under the three mountain ranges through which the Express Rail Link (XRL) passes, investigative boreholes had to be drilled a considerable depth, but many still did not reach the tunnel horizon, especially along the middle 6km of tunnels under Tai Mo Shan, Hong Kong s highest mountain. Using drill-and-blast excavation has enabled us to cope rapidly with the difficult ground conditions encountered in faults along this section of the alignment. The excavation of 35m of soft ground near Shek Yam, on the southern side of the mountain range, was tackled when the contractor switched to mechanical excavation after 12m long spiles and steel ribs were installed to support the tunnel. Like TBMs, drilling jumbos have undergone technological advances over the years. Today jumbos with 6m drilling rods can be pre-programmed for automatic drilling according to a set pattern. This is especially useful for controlling and minimising underbreak as well as The MTR Projects Journal 13

16 The sensitive application of drill-and-blast excavation After bulk excavation, waterproofing and tunnel lining works proceed inside Nam Fung tunnel between Admiralty and Ocean Park stations for South Island Line (East) Modern technology is employed for precision drill-and-blast tunneling, shown here on Express Rail Link 14 The MTR Projects Journal

17 The sensitive application of drill-and-blast excavation Magazine sites are established for security and control of explosives storage overbreak. It also means that blast holes are drilled very accurately, increasing the success of the blast in terms of the amount and shape of the excavation. The hard rock prevalent in Hong Kong tends to wear down drill bits quickly, and this must be considered in evaluation of drilling costs. Application of specialised tunnelling techniques The main challenge with drilling in such hard rock, however, lies in the high degree of jointing in the rock, where the jointed or fractured rock can jam the drill rods. Adverse joint orientations can also impact face and crown stability where, if not sufficiently pre-supported, instability of the face and crown can result. Some XRL tunnels have required temporary pre-supports to be installed due to poor rock quality. In a crossover cavern in the Ngau Tam Mei to Tai Kong Po section of XRL, heavy grouting has been required to address high water inflows through the joints in the rock. the blast face, including pre-existing tunnels, buildings, hospitals, archaeological features, schools, slopes and retaining walls. Mitigation measures for air overpressure, which can cause windows to rattle, include the use of noise enclosures to reduce overpressure from the shock waves created by each blast. These also serve to contain flyrock. Depending on the ground conditions as well as the need for air-overpressure and vibration control, the charge weights per blast hole must be adjusted, with lower charge weights resulting in a shorter advance per blast round. For example, for an excavation to progress at an average rate of between 4.5 to 5.8m a day in a 180m 2 face, more than 200 blast holes may be required with 12kg of explosives inserted into each, to be discharged with a small delay of 8 milliseconds between each blast. Where the blasting takes place close to SRs, the charge weight must be reduced in order to lower resultant air-overpressure and vibration levels. The tunnel face may be required to be split into additional headings to limit the number of blast holes where it is necessary to reduce the charge rate per round. Various new technologies have been adopted to minimise the impact of the blasting works on SRs. On the West Island Line (WIL), for example, we have used water as ballast to suppress both noise and dust from each blast. One of the main concerns of drill-and-blast excavation is generation of air overpressure and vibration associated with the use of explosives, which may impact neighbouring structures and slopes. We are normally required to monitor sensitive receivers (SRs) located at both surface and subsurface features surrounding Geophysical surveying to determine location of high-voltage cables A 6m x 6m pilot tunnel (left) enabled drill-and-blast tunnelling to proceed under high-voltage cable tunnels The MTR Projects Journal 15

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19 The sensitive application of drill-and-blast excavation Electronic detonators have also been used to more precisely time each blast and reduce vibration. One example is the excavation of a tunnel near Lei Tung Station on the South Island Line (East) (SIL(E)). The railway tunnel is located under two existing high-voltage cable tunnels with the closest separation being just 3.2m. The power company had initially declared a 27m no-blast zone and set a vibration limit of 12mm/sec. We were able to overcome this restriction by first excavating a 6m x 6m pilot tunnel at the lower left side of the proposed railway tunnel, away from the invert of the cable tunnels. There we conducted a series of detailed geophysical surveys to ascertain the actual separation between the cable and railway tunnels. The pilot tunnel was excavated with very low charge weights per blast hole. The pilot tunnel was then carefully enlarged with electronic detonators used to precisely control the delay between detonations, which each carried a charge weight of 0.12kg to 0.7kg, enabling the excavation to progress at 0.5m to 1.2m per blast. NONEL (non-electric) detonators are used to charge the blast face for the next tunnel advance for Express Rail Link Delivery and storage considerations Another challenge of drill-and-blast excavation is the delivery of explosives to site. For the public s safety, the Mines Division (MD) of the Government s Civil Engineering and Development Department (CEDD) only makes a limited number of road trips carrying a limited NEQ (net explosive quantity) each day. To ensure the construction programme will not be disrupted by a shortage of explosives, a magazine can be used for stockpiling cartridge emulsion, detonating cords and detonators. This provides flexibility for timing of deliveries such as at night time or in the early morning. For XRL, two explosives storage magazines were set up in Tai Lam and So Kwun Wat, having considered their proximity to the work sites and distance away from population centres. Hong Kong generally adopts the UK s Health and Safety Executive (HSE) Guidelines for safe distances permitted from population centres for placement of these magazines. For an underground magazine constructed to store explosives for WIL, the US Department of Defence Guidelines for Underground Magazines were adopted, as these contains more specific guidelines on rock spalling and shotgun effects associated with accidental explosive discharge in an underground explosive magazine. The shotgun effect includes a review of the impact of and travel distance associated with material and debris shot out of an underground adit or tunnel. Safety measures at the magazines include separate storage areas for detonators and packaged (cartridge) emulsion, the installation of robust CCTV systems and rigorous stock control. Regular audits of the stockpile are conducted by MD as well as our own auditors. To ensure public safety, contractors are required to transport no more than 200kg of explosives per delivery, using MD-licensed trucks. On WIL, we also commissioned a consultant to undertake a hazard-to-life assessment for the storage and transport of the explosives. Each magazine takes time and money to build and occupies unique spaces. Once decommissioned, alternative use of these spaces can be arranged. The 360m long U-shaped tunnel built at the WIL magazine has now been decommissioned and returned to Lands Department for future use. The two magazines set up for XRL, once decommissioned, may be reused to serve other infrastructure projects that involve drilland-blast excavation. The complexity of building railway tunnels in Hong Kong is compounded by its geological formations and its dense urban areas juxtaposed with sensitive and diverse rural areas. By applying new tunnelling technologies with a wealth of experience gained over the years, our engineers are driving tunnels further and deeper to bring MTR s railway lines to our customers desired origins and destinations. The MTR Projects Journal 17

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21 Complex Systems Designing and Managing Traffic around Sites The dynamics of interface management The MTR Projects Journal 19

22 Designing and Managing Traffic around Sites The largest and most complex temporary traffic management scheme in Hong Kong: West Kowloon Terminus, Express Rail Link Designing and Managing Traffic around Sites Bringing RAILWAY services into populated areas previously unserved by the railway network involves advanced engineering as well as complicated logistics planning 20 The MTR Projects Journal

23 Designing and Managing Traffic around Sites The scarcity of land in populated areas of Hong Kong usually means the whole or part of a new railway extension has to be constructed in public roads. Hence, a major element of urban rail extension projects is the planning for road and pedestrian traffic diversions at ground level to allow foundation and excavation works to proceed underground for the stations and railway facilities. These Temporary Traffic Management Schemes (TTMS) can involve shifting of traffic lanes, changing traffic flow from two-way to one-way traffic with detours, roadway rerouting, or temporary road closures. One of the more complex TTMS requirements is at the site of Whampoa Station, which will become the new terminus for the Kwun Tong Line Extension. This railway extension will reduce travel time from 25 minutes on the current overloaded roadway to just 5 minutes by train on a 3km journey from Mong Kok to Whampoa. This new station spans an entire city block, and its east and west concourses are located directly beneath two busy road intersections. To minimize impact on residents and traffic, an extensive TTMS was devised to enable pipe piling and excavation works to be carried out while keeping vehicular and pedestrian traffic flow moving. In the area around this one station, over 100 stages were designed into the TTMS to allow for progressive diversion of the existing maze of utilities, some uncharted, and enable the construction sequence to proceed with minimum impact to the community. From design to approval Designing and implementing the TTMS is a complex exercise that involves more than just ingenious traffic engineering considerations. Due to the wide variety of people affected, it requires extensive consultation with local residents and businesses, road-based transportation providers, District Councils and government departments. The general arrangements for the TTMS are typically set out by the design consultant prior to contract tender stage and finalised once the contractor is on board. Some of the critical criteria to be considered for successful TTMS include: minimising long traffic detours maintaining quiet condition of neighbourhoods ensuring safe conditions for traffic to pass by equipment and plant conducting major lane closures at night and reopening before the morning peak With all the stakeholders and government authorities involved, gaining approval for a TTMS is a complex matter in itself. Given the complexity of the construction sequence for railway projects and the tedious procedure for securing approval for TTMS under the normal government process, an accelerated process has been developed to allow the TTMS for railways to be considered and approved in a non-conventional, fast-track manner. Since the construction of the first MTR railway project, we have instituted Site Liaison Groups (SLGs) to facilitate the process of obtaining approvals. Jointly chaired by the MTR Corporation s Project Manager and the Highways Department Railways Development Office s Chief Engineer, the SLG s core members include officials from the government s Transport Department, Traffic Police, Fire Services, Home Affairs, and other departments, as required, together with the Contractor. With these resources assigned and meetings held regularly, the various stages of a TTMS can be discussed and approved quickly. The SLG is particularly useful because the traffic management plan proposed during the detailed design stage of a railway project is expected to undergo changes during actual implementation. Changes in work sequence or method Kwun Tong Line Extension's Whampoa Station east concourse site beside the recognisable cruise ship-shaped shopping mall The MTR Projects Journal 21

24 Designing and Managing Traffic around Sites TTMS stages for Kwun Tong Line Extension's Whampoa Station west concourse construction may affect traffic flow, and the traffic conditions at the construction stage may also be different from those during the design stage, thus requiring fine-tuning to the originally agreed arrangements from time to time during the construction phase. Securing smooth implementation Even after approval is gained, smooth implementation of TTMS requires close coordination and communication with the public. One example is the implementation of a large-scale TTMS on Ma Tau Wai Road, to facilitate construction of Ma Tau Wai Station as part of the Shatin to Central Link. In such an old district with bustling roadside activities, simply streamlining traffic demand by removing bus stops and eliminating casual parking would not work without the accep- tance of the community. Our approach was to launch a publicity drive to inform the public of the impending road closures in the area, advising motorists in advance to choose alternative routes to reach their destinations. Given advanced notice of reduced traffic capacity in the area, many motorists heeded the warning and avoided the area when the TTMS was implemented. We also worked with the bus companies to relocate bus stops and assigned Caring Ambassadors to help residents and other travellers locate the temporary bus stops, cross the road or explain other details of the TTMS. The result: unexpectedly smooth traffic flow through the busy district. Demand-side management often makes the difference between improved traffic flow and worsened congestion. During construction of South Island Line (East), we met with the authorities of several international schools located in Wong Chuk Hang area to discuss the impact of our TTMS on traffic in the area. We were able to win the schools cooperation in adjusting the school programmes, with some starting class minutes earlier and others starting minutes later. This small change proved sufficient to avoid congestion during the morning and afternoon peak hours. Working closely with the relevant District Council is also critical to the success of a TTMS. For example, we initially proposed to close two out of six lanes of Pok Fu Lam Road for up to six months to facilitate the erection of falsework for the construction of a footbridge connecting West Island Line s HKU Station with the University of Hong Kong s Centennial Campus. This however aroused concerns, particularly since the road is a key access for Queen Mary Hos- 22 The MTR Projects Journal

25 Designing and Managing Traffic around Sites pital. As an alternative, we proposed the intermittent closure of all lanes during the night for two weekends. This alternative was discussed in a town hall-style meeting before being taken through a trial run on a Saturday night. As the road was principally used by taxis in the small hours, we also sought the help of taxi associations to warn their members against using the road during this period. As a result, the footbridge was successfully lifted without adverse impact on access to and from the hospital. Importance of open dialogue The importance of maintaining communication with the District Councils is also demonstrated by the willingness of District Councillors to accept a TTMS that involves complete road closure. Although the construction of the West Kowloon Terminus of the Express Rail Link is a massive project, we had agreed not to reduce the number of traffic lanes in the area during construction. This however posed a challenge as our only option then was to shift the existing roads left or right while a new underground road network is constructed to replace the existing network. Eventually, we came up with an alternative involving the provision of a number of temporary roads that would enable us to close two existing roads. By explaining to the District Council the improved traffic flow that would result from speedy completion of the underpass, we were able to secure the Councillors support for a four-year closure of a key southbound road as well as the permanent closure of another road, once traffic was diverted to the temporary roads to the east of the site. To secure the public s support, open dialogue must be established to understand the particular needs on a case-by-case basis. Through active listening, we can respond to meet the needs, by providing temporary roadside facilities as well as other facilities that will help the locals adjust to the change more easily. Examples include the provision of wheelchair access for an elderly home in Western District, to compensate for the obstruction posed by kerbside fencing erected for the construction site, and the temporary relocation of two hawker stalls in the same district. With a high degree of planning, coordination with authorities, and cooperation with the public, the TTMS can be effectively implemented TTMS designed to keep traffic and businesses running while construction progresses With a high degree of planning, coordination with authorities, and cooperation with the public, the TTMS can be effectively implemented and benefit the smooth progress of the railway project. and benefit the smooth progress of the railway project. In some cases, the TTMS proves not to be an inconvenience as some traffic diversions result in improved traffic flow in the area. Occasionally, the TTMS even becomes a permanent arrangement as a result of improved traffic flow following its implementation. Whether the TTMS is a welcome improvement in the community or a necessary inconvenience to be borne for the longer term improvement in the railway network, MTR Corporation has learned through decades of experience that the process of planning, approving, and implementing a successful TTMS hinges on our ability to communicate, consult and coordinate through every stage of this people-driven activity. The MTR Projects Journal 23

26 The dynamics of interface management The dynamics of interface management On a railway project, the interfaces stretch the boundaries of complexity Station construction requires coordination among multiple systems and services, shown here at West Island Line HKU Station 24 The MTR Projects Journal

27 The dynamics of interface management 24 The MTR Projects Journal Simplified systems interface diagram Every construction project involves many interfaces, between the civil works, building services, architectural and electrical and mechanical contractors. The number of interfaces increases exponentially with the number of contracts and systems involved. In a railway project involving trains, signalling and network controls, specialist expertise and coordination are required. The challenge is compounded by the fact that the interfaces are not only limited to activities on any single site, but are spread across an entire railway line and often involve the operating railway as well. For example, trackside installation works such as cable laying and trackside equipment transportation require works trains which must be coordinated to ensure different contractors have access to them as needed within a restricted time window and to avoid disrupting train services where operating lines are involved. Defining physical and functional interfaces Another facet adding to the complexity of interface management in a modern railway project is that interfaces are not confined to those visible physical interfaces mentioned above, but also embrace intangible interfaces known as functional interfaces. This is particularly important for the many railway systems involving electronic processing systems and software, e.g. rolling stock, signalling, lifts and escalators, HVAC, and supervisory control and data acquisition (SCADA). Both the intangible interfaces and those visible interfaces require proper management to ensure the safety, reliability and proper functioning of the railway can be delivered. Very often more than two interfacing systems are involved in realization of one specific railway function. The management of these intangible interfaces across a large number of disciplines is a real challenge to the project delivery. Interface management is critical to project execution to maintain both harmony and progress. We have therefore adopted a systematic approach towards this element of our projects by clearly identifying pairs of interfaces and defining the roles and responsibilities of the relevant internal and external parties in managing each interface. Interface management begins at the project definition stage of a project and continues all the way through to project delivery. Project Definition Documents are used to baseline the requirements of each project while system interfaces are detailed in the Interface Requirement Specifications (IRS). The IRS define the technical scope, critical performance requirements, roles and responsibility for the interfacing components of every pair of systems. An interface matrix is used to show every interface between two systems. With each pair of systems having interfaces on average and multiplied by the number of systems involved on a railway project, the interfaces involved can number in the hundreds, especially on a railway line with many stations. During construction stage, the IRS will be used by the contractors to further produce detailed interface documents for design and testing. We also use System Integration Functions (SIF) to help us maintain focus on those key functions critical for the opening of a railway, involving intangible functional interfaces. This is an important tool for monitoring such intangible functional interfaces among the thousands of functional requirement of a railway. SIF are identified during preparation of the Project Definition Documents and usually involve the The MTR Projects Journal 25

28 The dynamics of interface management integration of as many as systems on a typical railway project. A project life cycle of interfaces The interface challenge also involves the coordination of various construction works during the design, construction and testing and commissioning phases. For example, a station s design must take into account the need to accommodate trackside equipment. During construction, detailed programming ensures all contractors have the required access to carry out their work without interrupting each other. Finally, all structures and systems are checked during the testing and commissioning stage to ensure seamless integration with the existing network. Increasingly, building information modelling (BIM) is used to carry out clash analysis and coordinate the different works. It is a visualisation tool that facilitates both the design and collaboration among different parties. BIM is now specified for the modelling of four main types of components: architectural, structural, building services and railway systems. By improving design coordination, facilitating construction coordination and carrying out clash analysis, BIM has helped our interface management during both the design and construction phases. During the construction stage we use a range of programming tools to help us manage the various interfaces. Coordinated Installation Programmes (CIPs) are used to detail the sequence of activities to be carried out in specific areas by different contractors during set time windows when they will be given access. For example, a civil contractor will provide access to a plant room for a building services contractor for a certain period of time to install equipment before the plant room is handed back to the civil contractor. A preliminary CIP will first be drafted by the Project Programming Team to integrate with contractors individual programmes. Workshops will be arranged to agree on the programme and draw out any interface conflicts between contractors whilst extra provisions will be considered to iron out the interface conflicts along the critical path. After the contract-specific interface issues are recorded, the preliminary CIP will be revised to finally form a CIP which will be dynamically updated according to actual progress. Construction at the South Island Line (East) Wong Chuk Hang Depot integrates the systems and works of many contracts Tripping into testing and commissioning The Track-Related Installation Programme (TRIP) is another programme tool applied specifically to track-related works, such as track-laying and trackside equipment installation. It is used to coordinate activities requiring the use of works trains, assigned to contractors according to the sequence of activities on each section of track and the contractors input. There are two types of works trains: engineer s trains usually used for routine maintenance are allocated by our operations colleagues to support trackside installation works on new projects; and new works trains procured to serve specific projects. Where there are interfaces with the operating railway, say work on the Kwun Tong Line Extension at Yau Ma Tei Station, we must follow operating railway procedures by submitting a request through the Engineering Works & Traffic Information Management System (ETMS) three weeks before the engineer s trains are needed. The detailed possession arrangement and allocation of engineer s trains can be confirmed once a Traffic Notice is issued. For greenfield sites with no interface with the operating railway network, new works trains are procured. Since they cannot be taken to site via the operating network, their loading and unloading locations have to be planned and identified during the detailed design stage. For underground tunnels, temporary openings are usually left at ground level for lowering the works trains and for loading and unloading of equipment to be installed. On Shatin to Cental Line, for example, the works trains will be lowered into the tunnel through an opening in Kai Tak, near the former airport runway. Finally, during the testing and commissioning phase of a project, all system integration functions are checked for compliance with the IRS set out in the contracts before a project is handed over to our operations colleagues. All system interfaces defined in the IRS undergo integrated tests. Testing and commissioning requires meticulous planning and execution as there are so many systems and pairs of interfaces to be checked, making the final delivery of a railway project a uniquely complex exercise. 26 The MTR Projects Journal

29 The dynamics of interface management Building information modelling assists coordination of multiple railway systems and building services Works trains play a vital role in the track related installation programme The MTR Projects Journal 27

30 28 32 The MTR Projects Journal

31 Putting Theory into Practice Admiralty Station: Engineering challenges to create a major transport hub Preserving our heritage, Progressing for the future Upgrading operating lines for future railway services Building an architecturally inspired highspeed rail terminus for Hong Kong The MTR Projects Journal 29

32 Admiralty Station: Engineering challenges to create a major transport hub Admiralty Station: Engineering challenges to create a major transport hub Few passengers using the MTR s Island Line and Tsuen Wan Line at Admiralty Station would be aware of the highly complex and challenging civil engineering works taking place under their feet Admiralty Station, currently a two-line interchange, is in the process of being transformed into Hong Kong s first four-line interchange station, with six levels of underground space being excavated to accommodate the platforms and tunnels for South Island Line (East) (SIL(E)) and Shatin to Central Link (SCL). The extension to the existing station is being built in a keyhole site beneath Harcourt Garden, surrounded by underground structures on all sides including Harcourt Car Park to the east and the existing station and platforms of the Tsuen Wan Line (TWL) and Island Line (ISL) to the west, north and south. While the new SIL(E) and SCL platforms will be accommodated within a deep cavern and platform tunnels, the works to integrate the old and new structures have required considerable ingenuity as well as innovation to overcome the station planning and engineering challenges. The new integrated Admiralty Station will more than double the existing station footprint. It is designed to facilitate fast and convenient interchange between the two new lines as well as the two existing lines. SCL Overrun Tunnels Cavern and Tunnel : Excavation by drill-and-blast method Between platform tunnels being constructed for SCL, a rock cavern has already been excavated to the south of the existing station to accommodate the SIL(E) platform, and structural works are well under way. Underpinning and excavating beneath Island line The excavation of the rock in the cut-and-cover section has required the use of mechanical breaking with the extensive use of large excavators of up to 85 tons in size, supported by drill-and-blast excavation. For this work to proceed, significant stakeholder interface with Existing Admiralty Station SIL(E) Cavern and Tunnels Admiralty Station Extension Island Line Underpinning New Extension : Excavation by mechanical and drill-and-blast methods Government and MTR Operations and Railway Protection has been required. Robust work methods and blast designs have been developed by the project team to undertake the work safely and to minimise the impacts to the existing railway structures. Excavation is now 38m below rock head and some parts of the site have now reached formation level. The delicate excavation underneath the ISL running tunnels is necessarily 30 The MTR Projects Journal

33 The MTR Projects Journal Drill-and-blast method has been used to excavate the cavern and tunnels for the future South Island Line (East) and Shatin to Central Link tunnels adjacent to the existing Admiralty Station 31

34 Admiralty Station: Engineering challenges to create a major transport hub Underpinning of the Island Line, with progressive excavation between temporary supports 32 The MTR Projects Journal

35 Admiralty Station: Engineering challenges to create a major transport hub The safety-first approach is the top priority in the delivery of the complex construction and in managing the challenging interfaces with the operating railway. proceeding carefully and methodically. This involves complex underpinning beneath the ISL and involves 28 temporary structural steel columns progressively installed and then extended incrementally as the excavation continues downwards. The underpinning works span 58m in length and extend up to 19m wide and 26m deep. The final stage of the underpinning works will see any temporary columns in permanent locations encased in concrete to form the station structure, and all other temporary works will be removed. The existing structure is supported by a series of prefabricated steel beams installed during the initial excavation process and then concreted in place. The existing structure is then supported on steel columns and jacks, with a computerised jacking system to control movement of the structure. Stringent engineering control is adopted so as to ensure the operating railway is provided with maximum protection at all stages of the work. With the safety of the operating railway as the principal concern, redundancy is inherent in both the design and methodology employed for the underpinning. Beams, columns and jacks are all designed with appropriate factors of safety to meet all Hong Kong building stan- dards whilst providing redundancy for a lost column support scenario. The method of excavation and rock support is managed through a three-stage permit system. Multiple headings are carefully advanced with the rock support being installed to the side walls and face before the next advance can commence. The work is proceeding 24 hours a day and seven days a week with full-time specialist supervision on site monitoring all the underpinning systems. The support structure for the underpinning works involves approximately 2,500 tons of Complex system of underpinning uses 28 temporary steel columns to support the operating Island Line during excavation below The MTR Projects Journal 33

36 Admiralty Station: Engineering challenges to create a major transport hub 34 Trimming The to formation MTR Projects and foundation Journal work in progress for the new Admiralty Station extension

37 Admiralty Station: Engineering challenges to create a major transport hub Building information modelling assists the design and construction of congested reinforced concrete members steelwork and 1,700m 3 of concrete. A total of 164 jacks with a capacity of 610 tons each are connected via five hydraulic pumps. Supported by the hydraulic jacks, the load will be transferred between each adjacent slot as the underpinning works proceed systematically down to final formation level. With only half of the jacks engaged at any one time, this over-capacity ensures the ISL slab is adequately supported at all times. Locking rings with a capacity of 900 tons each ensure that, should there be a problem with the hydraulic system, the supported structure will only settle a maximum of 1-2mm. Innovating for safety To monitor movement and the load on the temporary works, seven separate monitoring systems are in operation providing automatic real-time information. Three separate Automatic Deformation Monitoring Systems (ADMS) have been installed in the tunnels and the cut-andcover section to monitor different elements of the existing railway and the temporary works. In addition, 3D vibrating wire sensors have been installed at the joints of the existing ISL structure. Load cells provide constant real-time loads on the columns and stroke sensors measure any movement between the top of the underpinning column and support beams. The ADMS includes traditional robotic total stations and targets as well as vibrating-wire technology that uses liquid sensors to monitor structural movements. Whilst vibrating wire technology is not new to Hong Kong, its use combined with the liquid level system is a first in Hong Kong. The system is proving itself to be highly accurate with a tolerance of ±0.1mm, and with readings being taken every two minutes it provides key information as part of the monitoring of the structure. An equally stringent monitoring regime is also implemented to ensure nearby buildings, roads and pedestrian accesses are not affected by the excavation works being carried out for the station extension. Structural surveys of nearby buildings are conducted during the works and the impact of blasting-related works is also regularly monitored. Building Information Modelling (BIM) has been used to create a 3D model for the new station structure, including the complex reinforced concrete works. This has proved critical in ensuring the supporting elements fit together and meet the tight tolerances required. For example, it has been used to avoid clashes in reinforcement at the very congested beam and column interfaces in both the cut-and-cover areas and the ISL underpinning zone. To convert Admiralty Station from a simple two-line interchange to a major four-line hub in the heart of Hong Kong s central business district, the project team has established robust engineering solutions and put in place rigorous on-site management controls, including 24-hour specialist supervision of the works. This safety first approach is the first priority in the delivery of the complex construction and in managing the challenging interfaces with the operating railway. When completed, the new Admiralty Station will be established as a world-class transport interchange. The MTR Projects Journal 35

38 Preserving our heritage, Progressing for the future Diaphragm walls for Shatin to Central Link's Ma Tau Wai Station are being constructed adjacent to buildings along Ma Tau Wai Road 36 The MTR Projects Journal

39 Preserving our heritage, Progressing for the future Preserving our heritage, Progressing for the future Building the Kowloon City section of Shatin to Central link involves protecting old buildings, coping with busy roads and preserving Hong Kong s heritage Threading a new railway line through public land in order to avoid land resumption has always been a challenge in built-up Hong Kong, and perhaps nowhere more so than the Kowloon City section of Shatin to Central Link (SCL). The 22m wide, 320m long Ma Tau Wai Station is being constructed under Ma Tau Wai Road. To maintain traffic flow, three stages of temporary traffic management schemes (TTMS) are being implemented, both to facilitate construction of the station box and to ensure the works will not affect the old buildings in the area. Up to three lanes of traffic are closed for each stage of the project. As the area has less northbound traffic than southbound traffic, the first two stages of TTMS will maintain one northbound lane and two southbound lanes. During the first stage, the three lanes on the east side of the SCL alignment were closed for the installation of a diaphragm wall up to 60m into the ground to act as the external wall for this three-level station. The three lanes to the west side of the alignment are closed for the second stage of TTMS for diaphragm wall construction on that side. In the third and final stage of TTMS, two middle lanes will be closed. The first stage of TTMS was particularly challenging due to the number of petrol stations and other facilities that required access. The west side of the road does not have similar access issues but is bordered by older buildings. The construction work is being carried out in close proximity to buildings that are more than 50 years old in some cases. One is a pre-world War II building that dates back more than 70 years. Prepared with Alert, Action, Alarm To protect these delicate older buildings from potential settlement due to the station excavation, temporary cross walls are being built between the diaphragm walls to strengthen the station structure and prevent slippage of the ground below the buildings. These concrete cross walls, believed to be used for the first time in Hong Kong, will be broken through as the slabs are completed through top-down construction. Construction of the diaphragm walls involves the use of rigs that are more than four storeys high. The activity of such heavy equipment in close proximity to the buildings naturally gives rise to concern over noise and vibration. To reassure residents, we have instituted vibration monitoring for more than 20 buildings in the area in accordance with our AAA procedures (for Alert, Action, Alarm) for handling vibration incidences. Under this arrangement, an alert will be triggered when vibration reaches peak particle velocity (ppv) of 4mm/s, action is taken when it reaches 6mm/s, and an alarm is raised when it reaches 7.5mm/s. Seven buildings identified as potentially more susceptible to vibration are monitored in real time, 24 hours a day. To date, vibration registered by these buildings has remained well within the allowable limits. The MTR Projects Journal 37

40 Preserving our heritage, Progressing for the future Removal of bored piles obstructing the TBM drives from Ma Tau Wai to Hung Hom below the East Kowloon Corridor 38 The MTR Projects Journal

41 Preserving our heritage, Progressing for the future With the construction work just 4m away from some of the buildings, special measures have been adopted to minimise safety issues, noise and general nuisance to the public as well. The special hoardings used on this project consist of transparent polycarbonate panels mounted on concrete to allow through natural light. Above these panels, patterned netting is provided for the public s safety. SCL passes under the East Kowloon Corridor to the south of Ma Tau Wai Station. As two piles supporting one of the flyover s piers fall within the tunnel alignment, they have to be removed before tunnelling works can begin. The process involves the construction of eight new piles and two new pile caps in a U shape around the base of the existing pile cap. Once the load of the pier has been transferred to the new foundation, part of the existing pile cap and piles will be removed. During the design stage, we identified a bored pile wall consisting of 17 one-metre diameter bored piles, which had been constructed as protective works for the pier supporting the highway. These bored piles are being removed before the arrival of a tunnel boring machine (TBM) in the area in the middle of Discovering archaeological heritage sites A 7.4m diameter slurry TBM is being used to drive the tunnel for this section of SCL. A launching shaft was constructed in the north, at the tip of the future To Kwa Wan Station, for the drive south towards Ma Tau Wai Station. Prior to works commencement on the station, which occupies part of the former Kai Tak airport, an Environmental Impact Assessment (EIA) was conducted. After taking into consideration past archaeological investigations and historical documents, the approved EIA report determined that the north area of Sacred Hill, where the eastern part of the station lies, potentially contained archaeological artefacts. A survey-cum-excavation was recommended in the area. During formation of the launch shaft in the western end of the site, however, workers discovered more than 500 old coins dating back to the Song-Yuan Dynasties (10th and 14th centuries). An archaeological watching brief was extended as per the request of Antiquities and Monuments Office (AMO). Some old building foundations and a square well were subsequently discovered in the south-western corner of the TBM launch shaft, in an area now marked as T1. Careful measures had to be planned to protect these historical discoveries while allowing the archaeological investigation and construction works to continue. In order to minimise the potential impact from weather and nearby Excavation of TBM launch shaft at To Kwa Wan Station site on hold pending protection works for archaeological features at area 'T1' The MTR Projects Journal 39

42 Preserving our heritage, Progressing for the future Elaborate archaeological dig in progress to preserve artefacts discovered from the Song-Yuan Dynasties works and subsequent to AMO s agreement, we installed a sheet pile wall around T1 after surveying and backfilling the square well and placed sand bags to stabilise the other archaeological features. Vibration detection devices have been installed to closely monitor their stability, which is also supervised by the archaeologists. The strutting designed to support the TBM launch shaft has been changed to accommodate T1 while construction work continues. Thus excavation of the station and launch shaft has been split into two levels, with the protected T1 remaining at a higher level while excavation continues down to the track level in the unaffected area. Progress for the future while preserving the past Constructing the To Kwa Wan to Ma Tau Wai section of SCL has presented a combination of known and emergent complexities that need to be managed to deliver the underground railway through this delicate area. Not only is the project dealing with complexities of building in a brownfield corridor, with fragile old structures along a congested road artery, the preservation of heritage elements is playing a large role in this project s delivery. As the To Kwa Wan station is being constructed amidst an archaeological dig, extensive communication and collaborative efforts between engineers, archaeologists, the Government and the public have been necessary to preserve the heritage values while serving the best interest of our society. Ultimately, the opening of the SCL East West Line in this section of East Kowloon will be a major factor contributing to the revitalisation of the Kowloon City District, with new transportation infrastructure and preserved cultural heritage. 40 The MTR Projects Journal

43 Preserving our heritage, Progressing for the future Not only is the project dealing with complexities of building in a brownfield corridor, with fragile old structures along a congested road artery, the preservation of heritage elements is playing a large role in this project s delivery. Installation of sheet piles using low noise/vibration piler and sand bags protect archaeological finds at area 'T1' The MTR Projects Journal 41

44 42 The MTR Projects Journal Platform strengthening and modification works along existing East Rail Line stations for the future Shatin to Central Link operations

45 Upgrading operating lines for future railway services Photomontage of automated platform gates and other platform upgrades at East Rail Line Tai Wai Station Upgrading operating lines for future railway services The oldest line on the MTR network is being retrofitted to form a STRATEGIC North-South corridor INCLUDING a fourth rail harbour crossing East Rail Line (EAL), the oldest line on the MTR network, and Ma On Shan Line (MOL) are undergoing retrofitting works involving platform modifications and the installation of Automatic Platform Gates (APGs) as part of their integration with the future Shatin to Central Link (SCL). These projects comprise the installation of 2,300 APGs on 53 platforms at 21 stations along the two lines. Structural modification of existing platforms on these operating lines is necessary prior to the APG installation, particularly in EAL stations, because the 40-year-old platform structures will be subject to additional loading induced by the newly installed APGs. The installation and safe use of APGs will require flat and uniform platform surfaces. Preparing for Automatic Platform Gates Recognising the construction constraints imposed by the operational railway, a simple design approach is adopted to utilize the inherent station stability to provide support to the platform edge. Instead of major reconstruction, steel bars are used to tie the platform wall to the station structure and the bar levels are carefully designed to avoid the concealed utilities in the platform slab. Meanwhile, undulation is observed on platform surfaces after many years of service. Re-levelling is required for the safe use of APGs. This is achieved by raising the floor with fast-setting screed which can sustain passenger use within hours. With the raised platforms, the danger of passengers tripping is mitigated by lifting the track (thus lifting the train floors) simultaneously. The level differences between train floor and platform are tightly controlled throughout the process to meet stringent operating standards. EAL platforms have shown irregular horizontal edges due to differential movements experienced over the years. To enable the commissioning of future SCL trains with wider car bodies, it is required to re-establish the EAL control base alignment and redefine the platform edges to best fit existing conditions. The new edges will provide sufficient passing clearance to the future wider trains. This is achieved by reconstructing the platform slab structure at the edge. Flexible gap protection, which can be easily adjusted to suit different trains running The MTR Projects Journal 43

46 Upgrading operating lines for future railway services at different stages, are put in place to control platform gaps during modification works and the required track slewing. In conjunction with the platform levelling work, this opportunity is seized to enhance the EAL platform environment by re-finishing the whole platform with new floor tiles and new floor markings. Durable stone floor tiles are selected and standardized platform markings are incorporated to give a coherent and modern appearance. Platform gradient is also refined to enhance passenger experience and comfort. Minding the platform gaps EAL platforms tend to have wider gaps than platforms on other lines as they have to accommodate different types of trains over longer platforms with greater curvatures. To protect passengers who may not notice the gaps after the APGs are installed, measures are being taken including the use of wider SCL trains and the introduction of mechanical gap fillers to reduce the stepping distance where excessive gaps are located. These fillers will work with the signalling system to automatically extend filler plates over the gaps on train arrival, before the train and APG doors open; and retract them on train departure, after the train and APG doors have closed. About 140 gap fillers will be installed at Lo Wu, University and Mong Kok East Stations where these platforms have the biggest curves and widest gaps. Although the design has minimised as much as possible many construction constraints, there are remaining difficulties confronting the construction works within the operating railway environment. Firstly, most of the platform edge modification works are carried out during the non-traffic hours, typically from 2.00 a.m. to 4.30 a.m. This limited time slot severely restricts the amount of work that can be done during each night. To exacerbate the matter, in order to work on the platform edge, the application for special access is required but this can only be allocated, on average, three times a week per station. To follow stringent Operating Railway requirements, works have to be well protected and all hazards minimised and inspected before a platform is reopened for public use and train service is resumed each morning. Retractable mechanical gap fillers such as these will reduce wide gaps at curved platforms Working in close partnership with the track maintenance team has ensured the designed gap and level difference are met throughout the construction. The rail track of a single platform may need to be lifted/slewed up to times at different sections in order to match the platform work staging and the final track alignment and profile. Even though the level of the steel bars to tie the platform wall to the station structure is carefully designed to avoid the concealed utilities in the platform slab, cable detection has still to be carried out before the works, to identify any unforeseen buried cables, conduits, services or obstructions. To avoid damaging these cables, which could lead to serious consequences, extensive detection has to be carried out before exposing them manually using hand digging. This is a very slow but necessary process. The APGs will be installed after the new signalling system and trains for SCL are in place. They must operate in tandem to ensure the train door operation is accurately aligned with that of the APGs. Installed during non-operating hours at night, APGs will be tested immediately to ensure accurate operation and coordination with the signalling system and commissioned into service the following day. MOL platform gates and extensions Platform strengthening to some MOL stations is also being carried out in preparation for APGs. Here, the presence of noise absorptive panels, cable brackets and railway systems significantly limits the available space under the platform void and complicates the strengthening design and installation. The strengthened platforms are being enhanced with steel struts to withstand the additional shear and bending moment due to the wind and crowd loading on the APGs. This approach towards platform strengthening removes the need to reconstruct the platform wall and slab, which would be more highly disruptive. All MOL platforms are being extended by up to about 100m to accommodate the increase from four-car to eight-car trains. Thanks to some structural provisions already allowed in the MOL design, such as the steel couplers and cast-in bolts, impact on the operating railway line is significantly minimised. With the close proximity to the operating line, most of the work is carried out during non-traffic hours. For the Wu Kai Sha terminus station, it has been possible to carry out some works during daytime with alternate closing of the platforms during non-peak hours, without significant impact to the operation. This strikes a good balance between the noise impact of night-time works on nearby residents and the impact to the railway s operation. The modifications to the existing stations of MOL and EWL are paving the way for the expanded services of the SCL s East West Line and North South Line, respectively. Executing these changes in the operating environment requires complex planning, engineering and coordination for continued smooth and safe operations on the existing lines while enabling the effective delivery of even greater SCL services in the years to come. 44 The MTR Projects Journal

47 Upgrading operating lines for future railway services Structural modifications underway along East Rail Line to upgrade 40-year-old platforms Platform extension works in progress at Che Kong Temple Station on Ma On Shan Line The MTR Projects Journal 45

48 Building an architecturally inspired high-speed rail terminus for Hong Kong Artist's impression of West Kowloon Terminus Entrance Building incorporating green spaces Building an architecturally inspired high-speed rail terminus for Hong Kong Construction under multiple contracts, fabrication of an iconic roof and quick design turnaround are among the challenges of building this vast structure On a site about the size of the passenger terminal at Chek Lap Kok, we are building the terminus of the Express Rail Link, Hong Kong s portion of the China High Speed Rail Network. Unlike the air passenger terminal, however, the facilities and services in the West Kowloon Terminus (WKT) will be completely located underground. It is a large- scale complex structure covering more than 380,000m 2 gross floor area. It consists of four basement levels, two storeys above ground level, a three-level underpass system, road works, external drainage and utility works, eight footbridges, two pedestrian subways and two noise mitigation decks. Construction method For a normal underground station, diaphragm walls are built around the perimeter of the station with a system of struts installed for lateral support (excavation lateral support ELS). As the 12ha site of the WKT is too large for conventional ELS, soil is retained on both sides of the excavation and different methods of construc- 46 The MTR Projects Journal

49 Building an architecturally inspired high-speed rail terminus for Hong Kong Works progressing on the superstructure for West Kowloon Terminus, including nine mega-columns and a multi-system roof of aluminium and glass, as shown in the building information model rendering tion are adopted depending on the location. The bulk of the terminus is being built using a pseudo top-down method. In this, the middle portion of the structure is built from the bottom up while the perimeter is built from the top down utilising support from completed slabs while the retaining soil is removed from the lower levels. Due to the size of the terminus, construction is divided into several contracts to complete the terminus structure and diaphragm wall. Using the different methods of construction top down, bottom up, and pseudo top down the contractors are working simultaneously and in coordination to meet the challenging programme. This approach means the site, though large, is highly congested and interface management is essential. The site s location in the heart of a busy road network adds further complication. WKT is bounded on all four sides by main roads, making access for materials handling particularly challenging. A temporary traffic deck has been provided and various temporary traffic management schemes have been staged to maintain traffic flow. As a result, the peripheral works are split into sections being constructed in individual cofferdams and backfilled so the roads can be shifted before more construction is carried out in adjacent cofferdams. Two concrete batching plants were built specifically for two of the WKT contracts to reduce the number of lorry movements required. For the northern terminus section, concrete is pumped through three pipelines directly from plant to pour, over a distance of 500m. Despite this, concrete lorries are required to bring in additional concrete from a batching plant at Tsing Yi, over 10km away, to suit the demand for concrete for the various pours on a given day. With construction and excavation taking place across the site, storage space is at a premium. To maintain productivity despite the lack of space to store reinforcing steel, bar-bending yards have been set up in various parts of the The MTR Projects Journal 47

50 Building an architecturally inspired high-speed rail terminus for Hong Kong Complicated interfaces between permanent and temporary works site to supplement output from a bar-bending factory. Two bar-bending yards are also set up off-site. All the works are being carried out as more than 100 dewatering pumps operate to keep the site dry. Due to its waterfront location, the site has a high water table of +2mPD. On average the pumps remove enough water to fill half a swimming pool every day and much more during rainstorms. Spoil removal A dedicated barging facility is set up to remove excavated materials by sea, to avoid overloading the road system. All the changes and coordination are carried out at a running pace as the excavation, roof erection, temporary works and permanent works evolve in parallel. Excavated materials are lifted out of the deep basement for transfer to the barging facility. The ground consists of rock at -10 to -20mPD, on top of which is a mixture of completely decomposed granite (CDG), alluvium, marine deposits and backfill used to form the reclaimed area. The barging facility is equipped with three holding tanks for sorting the materials, with spoil being disposed of at various marine and land locations. Waste found in the spoil is removed before disposal. Due to the barging facility s proximity to the China Macau Ferry Terminal, there are three peak ferry periods from 8:00 to 10:00 a.m., 12:00 to 2:00 p.m., and 6:00 to 8:00 p.m. when barge access is not permitted. Given the volume of material involved and the limitation on barging, alternative disposal has been arranged whereby excavated rock is taken to another barging facility in Nam Cheong for handling. Roof erection WKT will feature an architecturally striking steel roof made up of 8,500 tons of structural steelwork forming a geometrically complex series of V-shaped trusses supported by nine groups of curved steel columns. It will have a clear height of 49m, and the longest truss will span 175m with a maximum free span of 48m. A high degree of accuracy is required in the fabrication and erection processes as each piece must 48 The MTR Projects Journal

51 Building an architecturally inspired high-speed rail terminus for Hong Kong Footbridges Connecting Location 1 To Kowloon Station and Developments To Kowloon Station and Developments To Kowloon Station and Developments 4 To Public Transport Interchange 5 To Austin Station 8 6 To Austin Station LIN CHEUNG ROAD UNDERPASS To Public Transport Interchange and surroundings Jordan Road Footbridge (reprovision) AUSTIN ROAD WEST UNDERPASS WEST KOWLOON CULTURAL DISTRICT (FUTURE) A network of roads, footbridges and subways will connect the West Kowloon Terminus with its surroundings The works on the arch structure of the Entrance Building can be seen in the centre of the photo. The MTR Projects Journal 49

52 Building an architecturally inspired high-speed rail terminus for Hong Kong be made, delivered and installed in the right order to tight tolerances. The roof cladding system is equally challenging, comprising 11 different types of cladding systems that make up 5,000m 2 of cladding and glazing. There are 3,700 glass panels and 19,000 aluminium panels, of which 90% are geometrically unique. The trusses, which are up to 12m wide and 6m deep, are being fabricated in sections in factories in China and Thailand where we have stationed staff to monitor the production process closely. To make sure these elements fit together, truss assembly is rehearsed at the factories where they are bolted together and lifted to check for deflection, then taken apart again and shipped to site for reassembly. Each section is correctly aligned when delivered to Hong Kong, ready to be bolted together using up to 75mm diameter bolts with 3mm tolerance and lifted into position by one of three 60-ton capacity tower cranes. Casting of the concrete on top of the steel truss, which will form the permanent roof of WKT, takes place at 20m above ground. The 30m high curved steel columns are also being fabricated off-site and will be connected by central nodes weighing up to 57 tons each to form a tree-like support system for the roof. Building information modelling assists the construction process and the future management of the facility All the steel components are stored off-site and brought in as required for the erection process. The truss sections are brought in by sea via the busy barging facility, necessitating temporary suspension of spoil removal and aggregate delivery. Due to their massive size, the steel columns are delivered by long trailers requiring four to five hours of road closure at night. Fast-track design WKT s unique floor plate and layout requires a substantial quantity of drawings to depict the activities and functions of each level. The design covers 39 discrete architectural packages and 17 civil and structural packages that are inter-referenced within the package of each discipline and cross-referenced to other disciplines. Because they are all inter-related, a single change in one element will cascade changes across many drawings. Due to the iconic nature and huge scale of WKT, the design of the temporary works (excavation lateral support and roof erection) are complicated and have implications for the design of the permanent works. The temporary works 50 The MTR Projects Journal

53 Building an architecturally inspired high-speed rail terminus for Hong Kong designers and permanent works designers are working together during the construction stage to produce a consolidated design with temporary and permanent stage effects properly considered. Close coordination and multi-iterations are required, in parallel with the construction works, to ensure the structural integrity considering both the forces of the temporary works and those of the permanent works. Similarly, close coordination is required between the design of the architectural, civil and structural elements and the building services (BS) and system-wide installations, a process that involves thousands of drawings. The workload involved is all the more substantial as a result of changes transpiring with the West Kowloon Cultural District development, which interfaces with WKT. These kinds of design changes during the construction stage are resource-intensive and must be carried out quickly, in parallel with the construction. One of nine curved steel mega-columns, 30m tall, being erected to support the Entrance Building roof structure The Interface between the contracts for the southern and northern sections at ground floor level, West Kowloon Terminus The MTR Projects Journal 51

54 Building an architecturally inspired high-speed rail terminus for Hong Kong Artist's impression of Entrance Building and Austin Road West underpass All the changes and coordination are carried out at a running pace as the excavation, roof erection, temporary works and permanent works evolve in parallel. New details for the permanent works are issued regularly taking into account the requirements of the temporary works designers for ELS and roof erection, four designated building services sub-contractors and 20 other designated and specialist electrical and mechanical services contractors. Driven by the vision Building such a vast, architecturally inspired terminus in this sensitive location requires great care and coordination to manage each complexity individually and as part of the whole. Driven by the vision to complete such a special facility, not only for its transportation benefits but also for the beautiful space it will create in the West Kowloon district, our project team in collaboration with the designers, contractors, sub-contractors and many stakeholders are working together to bring this mega station to reality. 52 The MTR Projects Journal

55 廣深港高鐵 Guangzhou-Shenzhen- Hong Kong Express Rail Link Tai Wai Diamond Hill 沙田至中環綫 shatin to central link West Kowloon Terminus 觀塘綫延綫 kwun tong line extension 西港島綫 west island line 南港島綫 ( 東段 ) south island line (east) West Kowloon Terminus Facts & Figures 12ha / 380,000m 2 S i t e area/ GFA 3,700 19,000 Glass Aluminium //////////// p a n e l s roof cladding 100+ No. of dewatering pumps used on s i t e 8,000 tons permanent steel 3,300 tons Temporary Steel For Roof Structure 2014 MTR Corporation Limited. All rights reserved. Reproduction of this work or any party of it by whatever means is not permitted without the prior written consent of the MTR Corporation Limited. The MTR Projects Journal 53

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