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Demolition of Yau Ma Tei Carpark Building and Re-provisioning of Gascoigne Road Flyover under Central Kowloon Route Project

Demolition of Yau Ma Tei Carpark Building and Re-provisioning of Gascoigne Road Flyover under Central Kowloon Route Project

By the CV Division and the Highways Department

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Since the 1970s, the Yau Ma Tei Carpark Building (YMTCB) has provided parking space for the public in the prosperous Yau Tsim Mong District and has acted as a destination for local collectors and book lovers going on a treasure hunt1. During its Phase 2 Extension in the early 1980s, the YMTCB, famous for its “running tunnel”, was a section of the Gascoigne Road Flyover (GRF). The flyover, which spans across the building, is one of the recognisable symbols over the notoriously congested West Kowloon Corridor.


Self Photos / Files - figure01Figure 1: Night view of YMTCB before its demolition


In an effort to alleviate traffic congestion within the current road systems and provide an alternative route to connect East and West Kowloon, the under-construction Central Kowloon Route (CKR) aims to provide an alternative express route bypassing the congested Central Kowloon area. It is expected to shorten the journey time between Yau Ma Tei and Kowloon Bay during peak hours from 30 minutes to about 5 minutes upon its commissioning.


In the planning and design stages of the CKR project, the project team carefully evaluated various alignment options based on their potential traffic, environmental, social, and land use impacts. After a series of public engagement activities and thorough assessment, the team arrived at a preferred alignment (see Figure 2) that would avoid resumption and demolition of private buildings and address public concerns, such as local culture and heritage conservation, reprovisioning of community facilities and land use planning, and environmental issues. The preferred alignment involved constructing a 500-m-long section of the CKR tunnel along Kansu Street, between Yau Cheung Road and Nathan Road, which requires the tunnel to pass through the underground foundation stratum of the Kansu Street section of the GRF and the YMTCB, that is, about 20 m below. Therefore, there was a need to demolish and shift a 290-m-long section of the GRF (existing GRF) northward, along with the demolition of the YMTCB, which was part of the GRF’s foundation for subsequent tunnel construction underneath.


The CKR project team carefully evaluated various alignment options based on their potential traffic, environmental, social, and land use impacts.


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Figure 2: The preferred alignment of the CKR tunnel along Kansu Street


The demolition of the YMTCB posed significant challenges. Not only was the YMTCB located in the bustling Yau Ma Tei district, but it was also a busy part of the GRF that required to be shifted through the heart of the YMTCB. In addition, the necessity of preserving both north and southbound traffic, the restrictions for sight lines, and the proximity of neighbouring structures all place significant constraints on the alignment of the reconfiguring GRF (RGRF). The only feasible alignment option lies above the northern part of the YMTCB. As such, the YMTCB has to be demolished in phases to release space for the construction of the newly reprovisioned GRF eastbound while maintaining the part of the building to support the existing heavily trafficked GRF. Given such a setting, the Phase 1 demolition of the YMTCB and the reprovisioning of GRF (eastbound) had to be carried out on top of and in close proximity to the busy elevated GRF, with very limited working space surrounded by at-grade roads. These constraints tremendously increased the complexity of the works and Figure 2: The preferred alignment of the CKR tunnel along Kansu Street posed very high challenges to the planning, sequence, and methodology of the YMTCB demolition works and the RGRG construction, which demanded stringent safety requirements.


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Figure 3: GRF passing through the middle of YMTCB


This article will therefore discuss in detail how to tackle the above challenges in the YMTCB demolition and the RGRF construction. It covers topics including construction planning and sequencing, technical complexity, enhanced safety and environmental measures, adoption of innovation, and people-oriented measures. By exploring these key aspects, this article aims to provide insights into the challenges and considerations involved in the CKR project, as well as the importance of proper planning and communication for a successful outcome.


Construction planning and sequencing


The existing GRF was a 1.2-km-long flyover that connected Gascoigne Road to Ferry Street, passing through the YMTCB, forming a critical part of the West Kowloon Corridor. The flyover provides a crucial link for vehicles travelling from West Kowloon to the Cross Harbour Tunnel and Eastern Kowloon Corridor, and is designated as a red route in Hong Kong. It was therefore of utmost importance to maintain traffic flow along the GRF during the demolition of the YMTCB and the re-provisioning of the GRF. Any disruptions to traffic on this route would have significant impacts on the public from all walks of life, underscoring the need for careful planning and execution of the demolition and the re-provisioning works.


In view of the limited site area and the need to maintain the traffic flow at the GRF during construction, site utilisation and sequencing for the demolition of the YMTCB and the construction of the RGRF have to be planned holistically in conjunction with different stages of temporary traffic diversion arrangements to avoid adverse traffic impacts.


Phase 1 demolition of YMTCB and construction of eastbound section of RGRF


In order to fully address the challenges mentioned above, a series of discussions were conducted with the stakeholders and relevant parties regarding the proposed construction sequence and methodology for the demolition works. Eventually, it was decided to carry out the demolition of the 13 storeys YMTCB in two phases. Phase 1 demolition includes the demolition of the whole northern part as well as the 7th to the roof floor of the southern part of the YMTCB, while Phase 2 involves the demolition of the remaining part of the building after the diversion of GRF traffic to the newly constructed RGRF (eastbound) with a temporary extended deck.


With careful planning, the Phase 1 demolition of YMTCB was completed on 31 August 2021, to allow the construction of the section of RGRF (eastbound) at the northern side of the YMTCB. The whole RGRF (eastbound) was completed in April 2023. The two-way traffic on the existing GRF between Nathan Road and Ferry Street was then diverted to this newly constructed flyover, allowing the demolition of the remaining southern part of YMTCB (namely, Phase 2 demolition) and the portion of existing GRF in YMTCB, as well as paving the way for commencing the subsequent construction of the underground CKR tunnel and the RGRF (westbound).


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Figure 4: Photomontage showing Phase 1 demolition of YMTCB and Construction of RGRF (eastbound)


Phase 2 demolition of YMTCB and demolition of existing GRF


In view of the tight construction programme, both Phase 2 demolition of the YMTCB (namely, remaining southern part) and demolition of the existing GRF were carried out concurrently. The demolition of the existing GRF was carried out in two directions: from the middle, and portion by portion (see Figure 5). Each portion of the existing GRF was wire-cut into appropriate, smaller pieces to suit the lifting operation and subsequent removal from the site. To overcome the constraints of the limited site area, minimise disturbance to busy traffic, and fully utilise available space for accommodating the demolition plants and temporary storage of debris, Phase 2 demolition of the YMTCB was carried out in three stages as shown in Figure 6. Under this arrangement, upon completion of Stage A demolition and in tandem with Stage B demolition, the remaining YMTCB (which was indeed the section of the existing GRF passing through the YMTCB) in Stage C could provide a temporary platform for sitting of a crawler crane to assist the demolition of the portion of the existing GRF (namely, portion 13 in Figure 5) adjacent to the YMTCB. Both Phase 2 demolition of the YMTCB and demolition of the existing GRF were carried out concurrently such that no site idling would occur during both demolition works. The complex Phase 2 demolition works took about four months to complete and the whole demolition of the YMTCB was finally completed on 6 September 2023.


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Figure 5: Sequence of Phase 2 demolition of YMTCB and demolition of the existing GRF


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Figure 6: The three stages of Phase 2 demolition of YMTCB


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Figure 7: YMTCB before demolition (left), Completion of Phase 1 demolition (middle) and Phase 2 demolition (right)


Technical aspects


Demolition of the YMTCB


The YMTCB was a conventional reinforced concrete (RC) structure with a slab, beam, and column design. The record drawings revealed that the building was supported by caissons, Franki piles, and footings found on rock. The condition survey revealed that the YMTCB was generally in good condition, with minor cracks on the structural concrete and no severe deterioration to structural elements observed. To ensure the building was demolished in a proper sequence and in a safe manner, the top-down method with a reverse sequence of typical RC structure construction was adopted for the demolition works. Temporary supports between floors were provided to support the demolition plant load during demolition, and a detailed demolition plan was established.


In view of the demolition works being carried out above the GRF with live traffic, a sufficient buffer zone between the Phase 1 demolition area and the GRF below (namely, three floors on top and 500 mm clearance from both sides of the existing GRF) was intentionally provided for safety consideration. A structural stability check was required to ensure the structural integrity of the remaining building after Phase 1 demolition (see Figure 7). Given that a reverse sequence of construction was adopted for the demolition works, the vertical loads acting on the remaining building were significantly reduced after Phase 1 demolition, so there was no particular concern for the structural stability. Since the remaining building and the existing GRF inside it would be retained and remain in service, respectively, for a certain period of time until the commissioning of the RGRF (eastbound), a lateral stability check was also conducted for the remaining building to ensure its safety. For the structural stability check, S-Frame-R11 was adopted, and the analysis revealed that the structural stability of the remaining building after Phase 1 demolition was satisfactory, with no adverse effect on the building or its foundation.


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Figure 8: Temporary supports and structural analysis for the remaining building


Construction of the RGRF


The re-provisioning of the Temple Street and Ferry Street sections of the RGRF posed a significant challenge due to the constraints of maintaining a minimum headroom of 6.4 m to the ground and an extremely limited horizontal clearance of 400 mm to the Yau Ma Tei Temporary Public Library building, as well as the limited space between the RGRF and its immediately adjacent buildings. To minimise the construction impact on the busy at-grade traffic below and existing social-economic activities in the vicinity of Temple Street, and to allow adequate working space in the congested site, the CKR project team adopted an in-situ balanced cantilever form traveller method for the construction of the RGRF.


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Figure 9: Form travellers being erected in tight space


This construction method involved using the top of the pier as the initial anchor point for a pair of separate form travellers operating as a balanced unit, with opposite directions of span construction proceeded. Cantilevered construction was allowed by moving each pair of form travellers further away from a pier in tandem. This approach could avoid erecting extensive falseworks on the at-grade traffic area for the casting of concrete segments, thus avoiding the need of a temporary traffic division of the affected carriageway, as well as freeing up other at-grade areas below the bridge for other concurrent construction activities at ground level.


The cast in-situ segments also eliminated the need for complicated and heavy logistics in delivering large pre-cast segments to the site for assembly in the busy and crowded Yau Ma Tei area, as well as the need for fully or partially closing the at-grate carriageway and/or footpath affecting the busy traffic and existing social-economic activities. This method ensured that the construction work in such a congested site could be carried out quickly and efficiently while minimising the impact on the surrounding community.


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Figure 10: In-situ balanced cantilever form traveller method for the RGRF


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Figure 11: Construction of RGRF (eastbound) in progress


Enhanced safety and environmental measures


There is no doubt that carrying out demolition work in close proximity to the live traffic was the major safety risk of the works. In Phase 1 demolition, the live traffic on the GRF was only one wall away from the demolition works (see Figure 7). In Phase 2 demolition, the closest distance between the remaining YMTCB (the northeast corner) to be demolished and the RGRF (eastbound) was about 2.5 m only (see Figure 13). These risks needed to be carefully assessed and mitigated to prevent potential catastrophic impacts on the public.


Installation of steel canopies and use of saw-cutting method in Phase 1 demolition


For the demolition of the YMTCB, various precautionary measures were implemented, which included setting up bamboo scaffolding with catch-fans, erection of temporary covered hoardings and walkways along the exterior walls of the YMTCB.


To further protect the live traffic on the existing GRF during Phase 1 demolition work, steel canopies were installed at the YMTCB locations where the existing GRF was passing through the YMTCB (see Figure 12). Besides, for demolishing the structural members adjacent to the existing GRF, the saw-cut method rather than conventional machine breaking was used to allow the members to be detached from the structure in a more controlled manner, and thus over-breaking could be avoided.


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Figure 12: A steel canopy was set up to screen off the potential flying debris during Phase 1 demolition


Metal scaffolding and saw-cutting method in Phase 2 demolition


In view of the closest clearance between the remaining YMTCB (the northeast corner) and the RGRF (eastbound) (see Figure 13), the saw-cut method was again adopted to further reduce the risk of any demolition debris falling into the RGRF (eastbound) during Phase 2 demolition work. The three bays of walls, columns, beams, and slabs that were closest to the RGRF (eastbound) were demolished using this method. Besides, much stronger metal scaffolding rather than bamboo scaffolding was erected for the three bays closest to the RGRF (eastbound) so that it could better withstand the load and pressure from the demolition debris and strong wind. The metal scaffolding also has higher durability and better performance under adverse weather, which means that there is less possibility of the scaffolding falling apart or becoming loose under adverse weather such as typhoons, heavy rain, etc.


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Figure 13: Close distance between remaining YMTCB and RGRF (eastbound)


Use of hydraulic crushers for demolition work


Apart from the complex road network where the YMTCB was located, the YMTCB also abutted closely to residential developments, with the nearest residential development less than 20 m away from the demolition area.


The CKR project team took every possible opportunity to reduce noise nuisances during the demolition works; one example was the use of a hydraulic crusher in conjunction with a conventional hydraulic breaker for demolition works whenever possible. Compared with conventional hydraulic breakers, the operation of a hydraulic crusher would not involve percussive action and was much quieter than that of hydraulic breakers. The hydraulic crusher could achieve at least 20 dB(A) noise reduction (in terms of the sound pressure level measured at 7 m from the equipment). Nevertheless, if hydraulic breakers had to be used for breaking hard rock, the breaker tip was enclosed with sound-insulating material to reduce its noise impacts.


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Figure 14: Use of hydraulic crushers for demolition works




Adoption of Building Information Modelling (BIM)


Building Information Modelling (BIM) was extensively adopted in the delivery of the CKR project. This cutting-edge 3D modelling software proved to be instrumental in simulating crucial aspects of the project, such as the phased demolition of the YMTCB, the construction sequences of the RGRF, and the associated traffic diversions. By simulating the construction sequences for the demolition of the YMTCB and the re-provisioning of GRF, the actual site constraints and construction difficulties could be easily visualised, allowing early planning and resolution of any potential conflicts or risks. The BIM model also served as an effective training aid for frontline staff to learn about the details of the construction sequences and safety precautionary measures required to be implemented on-site, further enhancing site safety and quality.


Adoption of Automatic Deformation Monitoring System (ADMS)


During Phase 1 demolition of the YMTCB, there was live traffic on the existing GRF passing through the YMTCB. It was essential to ensure that the demolition work would not cause any significant movement of the structures adjacent to this section of the existing GRF. In this regard, ADMS was deployed to monitor the real-time movement of the sensitive parts of the YMTCB during demolition. ADMS consisted of total stations, monitoring prisms, and stable reference points. It collected real-time vertical and lateral movement data for the structures and transferred it to a designated management platform to monitor the sensitive structures' conditions. Alarm, alert, or action messages would be sent to all relevant parties for appropriate action once individual monitoring points had reached their respective threshold values. This method facilitated quick decision-making and allowed for proactive measures to be taken to prevent or rectify any potential disruptions to the live traffic at the existing GRF.


People-oriented measures


During the demolition of the YMTCB, the CKR project team fully demonstrated the collaborative team spirit and adopted innovative thinking and a people-oriented approach. They went the extra mile to listen carefully to the concerns of various stakeholders and address their needs proactively in the project details.


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Figure 15: Simulations of YMTCB demolition and GRF re-provisioning sequencing


The CKR project team went the extra mile to listen carefully to the concerns of various stakeholders and address their needs proactively in the project details.


The CKR project team specially arranged to close the car park progressively in three phases (see Figure 16) so as to allow time for car park users to look for other parking locations. To ensure uninterrupted provision of public services, the team had to ensure timely reprovisioning of public facilities such as the Yau Ma Tei Public Library (see Figure 17) inside the YMTCB before the commencement of the demolition works.


The night market near the Tin Hau Temple has long been a local cultural attraction. The demolition of the YMTCB would affect the hawker stalls of the Temple Street Night Market, which are along Shanghai Street in front of the YMTCB. In this connection, the project team also had to take due consideration in minimising the impact on the operation of these hawker stalls during demolition. For example, the CKR project team deliberately consulted the hawkers to enable them to continue their business at a provisional location during the construction works and provided a tailored-made temporary covered walkway along Shanghai Street as a safety measure for hawker stalls. In addition, the CKR project team engaged an artist who was born and raised in Yau Ma Tei district to create a long painting (see Figure 19) imbued with local characteristics to incorporate into the hoarding design, bringing vibrancy to the temporary covered walkway.


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Figure 16: Phased closure of YMTCB


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Figure 17: Re-provisioning of the Yau Ma Tei Public Library which was previously located inside the YMTCB


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Figure 18:Tailor-made covered walkway along Shanghai Street with higher headroom and wider space between posts to suit with the night market’s operation


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Figure 19: Hoarding painting with Yau Ma Tei local features


Closing remarks


The demolition of the YMTCB and the construction of RGRF in urban area with busy traffic presented an unprecedented challenge. Nevertheless, the CKR project team endeavoured to deliver engineering excellence throughout the project, leveraging proper project planning and innovative technologies to overcome these challenges.


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Figure 20: Completion of the demolition of YMTCB in densely populated area


The completion of the demolition of the YMTCB marked an important milestone for the entire CKR project. The CKR project team will continue to uphold a people-oriented approach, adhering to the principles of minimising public impact, prioritising safety, and caring for the needs of stakeholders. The unwavering dedication to these principles will be indispensable as CKR strives towards its target commissioning in 2025.




  1. The YMTCB was constructed in two phases. Phase 1 involved the construction of the northern carpark building and was completed and put into service in 1970. An expansion plan was announced in 1972. The proposal of having the GRF pass through the two-phase Carpark Building was adopted, and the GRF was completed and commissioned in 1977. Phase 2 (namely, construction of the southern carpark building and additional upper storeys) was also completed and put into service in 1983. Apart from providing 770 parking spaces for private cars and 76 parking spaces for motorcycles, the YMTCB also housed the Yau Ma Tei Public Library, government offices and facilities, etc.
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