Design and Construction Constraints PPVC requires huge land space for the production and storage of the volumetric modules. In the land-scarce Singapore, this has become a luxurious request and hence resulted in a unique arrangement of the modular construction process. Typically, the volumetric module will be fully fabricated within the same manufacturing factory for it's structural, architectural and mechanical-electrical-plumbing (MEP) components. For Singapore’s PPVC, the fabrication process is split into two parts: structural carcass factory in neighboring country (i.e. Johor, Malaysia) and architectural and MEP fit-out factory in Singapore. Even with the successful implementation of the 5 ICPHs up to date, they are only able to produce 20% of the total precast components required for the construction works and the industry is still highly reliant on Malaysia's factories for the remaining 80%. Designer and Contractor shall also ensure the PPVC module size allows transportation from factory to site and within the hoisting limits. Cost Implications Being Singapore's first private PPVC building that was completed in 2016, the cost premium of adopting PPVC in Crown Plaza Changi Airport Hotel Extension was estimated to be 10 to 15% more as compared to conventional reinforced concrete construction (Today, 2016). With the launch of Construction ITM in 2017 and more PPVC players have come into the market, the estimated cost premium has been further reduced to 8% as of February 2020 (BCA, 2020). The estimated cost premium of PPVC is mainly driven by the following cost factors: ● Precast Mould The PPVC module requires custom made mould which are unlikely to be recycled and reused for other projects. The higher number of the different modules in one PPVC project, the more precast moulds are required and hence, more cost to be added to the overall contract sum. ● Transportation Figure 1 Illustration of off-site factories in Johor, Malaysia and Singapore and the construction site. The other two deciding factors on the module design are transportation and hoisting limits. Logistics for module transportation from factory to site determines the maximum size and volume of each module design. In compliance to Land Transport Authority (LTA)‘s traffic regulatory requirements, the ideal dimension of a single PPVC module shall be as follow: ● ● ● Height: < 4.5 metres (inclusive of truck height) Width: < _ 3.4 metres Laden Weight: < 80 tons If exceeds the above controlling parameters, a LTA permit and Auxiliary Police Escort are required for the module transportation from point to point. The current available types of hoisting cranes (i.e. tower crane, mobile crane and crawler crane) have a similar lifting capacity of 25 tons to 40 tons, which dictates the maximum weight of a single PPVC module to be. As such, while making the layout plan design fully complies with regulatory requirements, the Compared to the one time transportation of the conventional precast concrete component, the PPVC module requires two times transportation before reaching the construction site, i.e. from carcass factory to the fit-out factory and from fit-out factory to the construction site. Also, in the event that LTA permit and Auxiliary Police Escort is required as highlighted in the previous section, the application cost for the permit and escort shall constitute an additional cost to the overall contract sum. ● Hoisting Crane The PPVC module generally requires heavy-duty hoisting cranes for on-site installation. The initial cost and rental of such cranes is considerably higher than typical capacity cranes. ● Off-Site Yard PPVC requires two off-site fabrication yards: carcass factory and fit-out factory. Additional costs are incurred for setting up, operating and maintaining PPVC manufacturing factories in Malaysia and Singapore. Additional cost in sending off-site and overseas supervisors is also required in ensuring the product quality and full compliance to the COP 2017. Contractual Framework Early Contractor Involvement (ECI) One of the key benefits of adopting PPVC is the significant construction time savings. For example, in The Clement Canopy, a 40-storeys high condominium took 7 days to construct a floor, compared to 14 to 21 days using conventional construction 00:0 6
7 Online Touch Home