Hong Kong Pioneering BIM For Housing Quantity Surveying .

Hong KongHousingAuthorityPioneering BIM forQuantity SurveyingProject:Construction of Public RentalHousing at Sha Tin Area 52Phase 1 (known as Shui ChuenO Ph 1)Location:Sha Tin, Hong KongType:Public HousingScheduled Time ofCompletion:February 2014The Housing Authority is implementingprobably the Greater China Region’s firstproject for obtaining detailed quantities datafrom a BIM model. The “5D” model – withthree physical dimensions plus time and costdata – generates data far more quickly thantraditional QS methods. The standardisedapproach and guidelines developed in theproject may extend the use of BIM in theconstruction industry.Lead the WayAutodesk Hong Kong BIM Awards 201231

Pioneering researchand design projectIn 2006 the Hong KongHousing Authorityfirst adopted BIM, andhas made remarkableachievements insustainable constructionand strengthening sitesafety through applyingBIM technology in designand site planning. Now,the Housing Authorityaims for all new projectsfrom 2014/15 onwards touse BIM.The success and futureplans prompted theHousing Authority’sQuantity SurveyingSection to investigate howto tap BIM’s potential forhelping to generate datasuch as quantities andcosts of construction projects. This could leadto several advantages over current practices.Traditionally, design intent and cost dataare often separated and isolated in differentdigital environments – making it extremelydifficult and time consuming to extract data forplanning and controlling construction projectfinance and risk issues.The Housing Authority decided toundertake a research in a housing projectunder construction, in partnership withthe contractor China State ConstructionEngineering (Hong Kong) Ltd. and the BIMconsultant isBIM Limited. As there is noprevious example of BIM being applied togenerate detailed quantities based on isBIM’s32 Lead the WayAutodesk Hong Kong BIM Awards 2012approach in the Greater China Region, thisproject could be said the first in the Region.BIM in parallel with traditional QSmethodsThe project covers a new public rental housingdevelopment in Shui Chuen O Phase 1 in Shatinof Hong Kong. This HK 1.3 billion developmentinvolves construction of five blocks with 3,039domestic flats. The research spans four worktrades which are Piling, Excavation, ConcreteWorks and Underground Drainage, whichtogether account for around HK 301 million ofthe project cost.Quantity surveyors are still applying

isBIM Limited. The modelcurrently has over 85,000objects.Using this model, teammembers developed asystematic approach forquantity takeoff process,costs management andcash flow simulationlinking the BIM databasewith a Cost database. Thisapproach was dubbedQuantity SurveyingBuilding InformationModelling (QSBIM).QSBIM aims to providequantity surveyors aneffective way to transfer,extract and verify thecost related informationfrom BIM modellingelements to a BQdatabase.conventional practices, taking manualmeasurement from drawings and transferringdimensions to sheets or spreadsheets tocarry out cost estimates or interim paymentassessments. The research runs in parallelwith this work, seeking a new way to useBIM information to boost efficiency andproductivity by automated quantification,increase accuracy by reducing data variability,and facilitate sharing of data amongstakeholders.Standardised approach andguidelines“One of the challengesin extracting quantities is the requirement tofollow the measurement rules in the HongKong Standard Method of Measurement ofBuilding Works (HKSMM),” says Sunny Choi,Senior Quantity Surveyor of the HousingAuthority. “Another challenge is differentmethods of building up BIM models will giveout different quantities.”isBIM drafted a standard approach ofmodelling for the four work trades, coupledwith standardised guidelines based on theHKSMM, to assist quantity surveyors to extractquantities data from BIM models.“At first, there was no BIM model – we createdone from 2D drawings,” says Elvis Li, CEO ofLead the WayAutodesk Hong Kong BIM Awards 201233

Over 200,000 measurementrecords generated directly fromBIM modelThrough integrating extracted quantities fromBIM model, construction programme and costinformation, the research team has created 5D[i.e. 3D models plus time (the 4th dimension)and cost (the 5th dimension)] cash flowsimulations, which help revealing actual andpredicted cash flow of the project.“So far, we have generated over 200,000measurement records directly from the BIMmodel,” says Mr Li. “There will be many morein future.”The research spans April to November thisyear, and the results will help to have a betterunderstanding on project cash flow. Mr Li34 Lead the WayAutodesk Hong Kong BIM Awards 2012demonstrates one way of showing the results,in which it is possible to select a time and date,and instantly show a 3D image of the partlybuilt housing blocks together with a graph andfigures indicating project costs.“Extracting quantities from BIM models is veryfast compared to manual measurements andcalculation for interim payment assessments,”says Mr Choi. “For the traditional practice, weneed to head back to the office after visitingthe site, and assess the amount of workscompleted, which may take one to two weeks.”Comparing the quantities obtained throughthe QSBIM and from traditional quantitysurveying practice, the difference is within10%; the discrepancies will decrease as the newmethod is fine-tuned.

May extend the use ofBIM in constructionindustry“If this method indeed worksas expected, we can introduceit to contractors,” says MrChoi. “If we find a constantdifference between QSBIM andtraditional methods or the gapbe minimised we may try touse QSBIM to speed up interimpayment assessment, which will be a win-winsituation for both the Housing Authority andcontractors.”Though the research primarily focuses on cashflow forecast and payment assessment, thegradual development of standard approachof modelling and measurement guidelinesallow QSBIM be extended to other quantitysurveying functions, such as preparing Billsof Quantities for BIM models. And it may beemployed far more widely within Hong Kong.* All images in this article are provided by Hong Kong HousingAuthorityLead the WayAutodesk Hong Kong BIM Awards 201235

About Hong Kong Housing AuthorityThe Hong Kong Housing Authority (HA) develops and implements apublic housing programme which seeks to achieve the Government’spolicy objective of meeting the housing needs of people who cannotafford private rental housing. Approximately 30% of the Hong Kongpopulation is now living in public rental housing units.The HA plans, builds, manages and maintains different types of publichousing, including rental housing estates, interim housing estates, andtransit centres. In addition, the HA owns and operates some flattedfactories and ancillary commercial and other non-domestic facilities. TheHA also supports the Government’s policy in providing subsidised homeownership flats to qualified persons.The Housing Department (HD) acts as the executive arm of the HA tohelp the Government achieve its policy objective on public housing.36 Lead the WayAutodesk Hong Kong BIM Awards 2012

consultant isBIM Limited. As there is no . Quantity surveyors are still applying Lead the Way Autodesk Hong Kong BIM Awards 2012 33 conventional practices, taking manual measurement from drawings and transferring dimensions to sheets or spreadsheets to carry out cost estimates or interim payment