Measurement (Taking-off) 计量

Taking-off 计量

  • The process of measuring the quantities is called "taking-off". Person(s) taking-off are called "Taker(s)-off"

Reading Standard Method of Measurement
阅读标准工程量计算规则

  1. The Standard Method of Measurement to be used should be clarified during the briefing session upon commencement of taking-off
    采用的标准工程量计算规则在开始计量的交底会确定
  2. Inexperienced Takers-off should read the relevant sections of the Standard Method of Measurement before taking-off
    生手计量员应在计量前阅读了解计算规则
  3. Experienced Takers-off should review the relevant sections of the Standard Method of Measurement from time to time during the course of taking-off
    熟手计量员应不时重温计算规则
  4. Upon completion of taking-off, all Takers-off should take a final review of the Standard Method of Measurement to ensure that there are no missing items to be measured
    计量完毕,全部计量员应翻阅计算规则,确保没有错漏

Extra attention to be paid to how to treat:
特别要注意如何处理的:

  1. Working space, slopes of excavated spaces
    工作面、放坡
  2. Staging
    步距
  3. Wastage
    损耗
  4. Laps, intersections
    搭接、交叉
  5. Circular work
    弧形
  6. Deductions for openings
    扣除孔洞
  7. Extra over items
    补差计量

Work measured net

  • Measure all work net as fixed in place, unless otherwise stated

Order of dimensions in BQ or dimension sheets

  • Generally in the sequence of length, width and height

Range

  • A - B = exceeding A but not exceeding B = "> A but <= B"

Pipe and tubing

  1. Pipe size: to be described by nominal sizes(HKSMM4) vs by internal diameter (HKSMM3)
  2. HKSMM3 only:
    • Small pipes = pipes < 55 mm diameters
    • Large pipes = pipes 55 - 110 mm diameters
    • Pipe size stated = pipes > 110 mm diameters

Circular work

  • HKSMM3 only:
    • Small radius = 0 - 300 mm radius
    • Medium radius = 300 mm - 1.50 m radius
    • Large radius = radius > 1.50 m

Piling

  1. Commencement level / commencing level:
    • Identify the commencement level of piling - existing ground level, level after general site levelling or bulk site formation, or bottom level of footing or basement excavation
    • State the commencement level in the BQ - the commencement level may not always be the formation level as stipulated by the SMM
  2. Usual items:
    • Mobilization and demobilization
    • Trial piles
    • Preformed portion (whole piles, linings only, driven or placed):
      • Supplying
      • Reinforcing if not described to be included in the supply
      • Driving
      • Dollying
      • Cutting
      • Withdrawal
    • Cast in-situ portion (whole piles, fillings only, pre-boring):
      • Boring
      • Reinforcing
      • Casting
      • Cutting
    • Heads, shoes
    • Testing:
      • Before piling
      • During piling
      • After piling
  3. Usual units:
    • Area for steel sheet piles or contiguous piles - Measure the area in plane (not developed) elevation along the centre line of steel sheet piles
    • Length for piles in isolated pieces
    • Length or number for extra over items or isolated items
  4. Supplying preformed portion (including handling, transporting and pitching) :
    • Describe clearly the method of measurement of the area or length or number of supply
    • HKSMM5 does not specifically state how the length is to be measured to give the supply quantity of steel sheet piling or precast concrete piles
    • It only requires the "design length" to be stated, but does not say that this is the length to be measured for supply quantity
    • "design length" is defined by HKSMM4 as the length specifically required by the designer. However, the designer often does not specifically specify the design length. He usually only specifies the length below cut-off. It is therefore essential to define design length or describe the supply length measured, e.g. as driven length or length below cut-off, with or without allowance for extra length above the top
    • The supply length can in some cases be shorter than the driven length if the top is required to be driven below ground (dollying)
  5. Driving piles:
    • Measure from commencement level of driving to bottom level of driven pile
  6. Corner piles, junction piles and other special piles to steel sheet piles:
    • Measure as extra over the supplying and driving items "respectively" of the steel steel piling into which they occur
    • Since the supply area may not be the same as the driven area, therefore, "respectively" should mean "separately" for supply items and driving items, or the description of the extra over items should be clear enough

Excavation

  1. Commencement level / commencing level:
    • Identify and state the commencement level of excavation
    • Usually, the commencement level would be the existing ground level or the formation level whichever is the lower at a particular point
    • Usually, "formation level" means the underside of the hardcore bed or blinding level of the lowest floor slab or external paving
    • Usually for a site to be "cut", i.e. formation level lower than existing ground level, the site would be formed to the formation level first, and foundations excavation would commence from the formation level
    • Usually for a site to be "filled", i.e. formation level higher than existing ground level, foundations excavation would commence from the existing ground level, backfilled and filled up to the formation level
    • "Usually" means that the definitions for specific projects should be defined and described in the BQ
  2. Working space:
    • 0.25 m from the face of concrete requiring formwork where the formwork does not exceed 0.60 m in height
    • 0.60 m from the concrete requiring formwork where the formwork exceeds 0.60 m in height AND the bottom of the formwork exceeds 0.60 m below the commencement level of excavation
    • 0.60 m from the finished face of work below ground level where externally applied dampproof coverings or protection walls are required or where the method of construction requires workmen to operate from the outside (NOTE, "ground level" should mean that when the workmen go down to do the coverings or protection walls but this should be clarified in the BQ)
  3. Usual units:
    • Number for post holes not exceeding 0.30 m3
    • Length for trench excavation
    • Area for surface excavation not exceeding 0.20 m in average depth
    • Area for backfilling or filling not exceeding 0.30 m in total depth
    • Volume for other excavations, filling and disposal
  4. Balancing:
    • Excavation = surplus disposal + backfilling
    • Import fill = filling to make up level - surplus disposal from excavation

Concrete works

Drainage

  • When classifying drainage trench excavations by the total depth in stages of 1.50 m, with the average depth stated in multiples of 0.25 m, instead of taking the maximum total depth at the one end of the trench and measuring the whole length into that deepest stage, the length of the trench should be divided into different sections according to the total depth stages and the average depth taken for the different sections

Finishes and roofing

  1. Related items should be measured as a composite items before billing to ensure consistency in quantities. e.g. plaster and paint; tiling and screed; roofing tile, waterproof layer, insulation layer, screed, etc.
  2. Adjustments to be made for differences, e.g. bands, borders, channels, curbs, etc.

Swimming pool measurement checklist

  1. Excavation:
    • Excavation to reduce levels
    • Excavation for swimming pool
    • Backfilling
    • Disposal
  2. Concrete:
    • Concrete blinding layer
    • Waterproof reinforced concrete in sides and bottom
    • Waterproof reinforced concrete angle fillet including formwork
    • Housing for scum channel
  3. Formwork:
    • Formwork to sides of swimming pool
    • Formwork to soffit of suspended swimming pool
    • Opening for view panel
  4. Reinforcement:
    • Steel bar reinforcement, stirrups, binders, etc.
  5. Waterproofing:
    • Waterproof membrane on sides and bottom of swimming pool
  6. Finishes:
    • Waterproof cement and sand rendering on sides and bottom of swimming pool and behind scum channel
    • Tiling and waterproof screed on sides and bottom of swimming pool
    • Scum channel in tile
    • Steps in tile
  7. Steel and metal works:
    • Cat ladder or step iron
  8. Pipework:
    • Puddle flange connector
    • Water supply pipes
    • Water supply outlets
    • Drain pipes
    • Drain outlets
  9. E&M works:
    • Filtration system and boiler

Water tank measurement checklist

  1. Concrete:
    • Waterproof reinforced concrete
    • Waterproof reinforced concrete angle fillet including formwork
    • Reinforced concrete plinth
  2. Formwork:
    • Formwork to sides and internal soffit of water tank
    • Left-in formwork to external soffit of water tank
    • Left-in formwork to form gap between walls
    • Formwork to concrete plinth
    • Boxing to form openings
  3. Reinforcement:
    • Steel bar reinforcement, stirrups, binders, etc.
  4. Waterproofing:
    • Waterproof membrane/coating on top
    • Waterproof membrane/coating on internal sides and bottom
  5. Finishes:
    • Waterproof cement and sand rendering to internal sides and bottom of non-potable water tank
    • Tiling and waterproof screed on internal sides and bottom of potable water tank
    • Finishes to top and external sides
  6. Steel and metal works:
    • Cat ladder or step iron (inside & outside)
    • Trap door or cover
  7. Pipework:
    • Puddle flange connector
    • Water supply pipe
    • Drain pipe
    • Overflow pipe
    • Air vent
    • Ball float valve

Door measurement checklist

  1. Doors and frames:
    • Door leaf
    • Vision panel
    • Louvred panel
    • Door frame including bedding and pointing frames
    • Intumescent strip around fire rated doors
    • Architrave
    • Ground behind door frame
  2. Ironmongery
  3. Sundry metalwork:
    • Holdfast to door frame in brick and block wall
    • Anchor bolt to door frame in concrete wall
    • Floor dowels
  4. Painting:
    • Painting to door leaf, door frame, architrave and ground
  5. Sundry concrete:
    • Lintol
    • Wire mesh for lintol

Mode of taking-off
计量的手法

  1. Measurement should be done in a logical manner
    应按有系统的次序计算
  2. For example, following the construction sequence or alternative logical sequence
    例如按施工顺序或主客关系
  3. Consistently from one direction to the other direction
    一致从一方算至另一方
  4. Setting out dimensions in a consistent manner of length, width and breadth
    将尺寸按长阔高的须序输入
  5. Avoiding breaking down irregular shapes into small pieces and then adding up
    避免把不规则的形状分拆得太细来计算然后加总
  6. Measuring overall first and making adjustments
    应计最大框,然后扣减调整
  7. Measuring related items in composite manner, e.g. tile and screed, plaster and paint, all layers of roof covering
    以组合式的方法把关连项一起计,编清单时才分项,例如块料面层和找平、屋面层

Long hand dimension sheets
长式计算纸

  1. Calculations may be set out in the usual arithmetical form:
    计算可如一般的算式列出:
  2. This uses less paper, but is difficult for comparison and inspection for errors
    这样非常省纸,但难于对比和检查错误

Traditional dimension sheets

  1. Traditional dimension sheets used to take-off quantities take the following form:
  2. Dimensions are set in vertical stack, in the order of length, width and breadth. A line is used to separate each set of dimensions
  3. Timesings are written on the left column. In this column, "/" means multiply, not divide. "" means add, an action called "dotted on"
  4. The products are given in the right column
  5. The descriptions are very much abbreviated to reduce writing
  6. The calculation in the description column is the build-up of one of the dimensions. It is called a "waste calculation" or "side-cast"
  7. The annotations "bm B1", "bm B2" in the description column are to identify the locations of sets of dimensions. This action is called "sign-posting"

Another kind of dimension sheets

  1. Another kind of dimension sheets is to lay out the dimensions horizontally as follows:
  2. The products of dimensions are not written one by one. Only the total of the products is entered. This is made feasible with the popular use of electronic calculators with memory function. It would be faster to calculate once more than write down all the products before summing up
  3. Laying out the dimensions horizontally actually improve the presentation and make comparison of dimensions easier
  4. The right hand columns can be utilized as rate and extension columns for final account purposes
  5. The following dimension sheet records the dimensions in a systematic manner. This makes comparison and identification of errors easier, and can measure concrete and formwork at the same time: 
    下列的计算表,把尺寸按一定的格式列出,对比清楚,找错容易,兼可同时计混凝土及模板:

Squaring 运算

  1. The process of calculating the totals of dimension sheets is called squaring. The person is called a "Squarer" or "Comptometer"
  2. To ensure correctness, each calculated total entered by a Squarer must be counter-checked and initialled by another Squarer. Squaring is a tedious process even with the help of electronic calculators before the use of computer spreadsheets or BQ production software

Abstracting

  1. Traditional dimension sheets measure more than one item on the same sheet. The same BQ item may appear on more than one sheet. Therefore, it is necessary to collate the individual quantities of the same BQ item appearing on more than one dimension sheet together to arrive at the grand total
  2. A summary schedule is used to bring together the individual quantities to add up the grand total. The process of transferring the individual quantities from dimension sheets to the summary schedule is called "abstracting"
  3. 计算纸或计算表列式后要运算
  4. 用普通计算器及人手计算的要另外有人复核并签署
  5. 用电子计算器及软件计算的,要建立复核公式复核

Billing 汇总卡

  1. The items in the summary schedule are then transferred to the draft BQ pages in the correct sequence with the descriptions expanded in full without abbreviations
  2. This process is called "billing" and requires experienced Surveyors to do
  3. The whole process from squaring to billing is called "working up"
  4. 计算纸或计算表运算后要汇总
  5. 工程量清单某分项数量可能要由几张计算纸或计算表得出,所以要汇总
  6. 每一个工程量清单分项都有一张卡,可以A4纸分为二
  7. 每卡都写上工程量清单分项的工程合同名称、卡号、清单号、分项说明、单位、计算纸或计算表编号、搬来数量、汇总数量。 格式例:

Transferring 转移

  1. Information is transferred from the dimension sheets to the summary schedule to the draft BQ. Every transfer of descriptions, units and quantities has to be counter-checked by another Surveyor. The actions are called "transferring" and "transfer-checking" or "to check transfer"
  2. 从计算纸或计算表转移到汇总卡后要他人复核签署
  3. 从那里来往、往那里去,都要写

Cut and shuffle 排序

  1. Abstracting and working up are tedious processes involving a lot of transferring and transfer checking. More movements of information from one to another will increase the chances of making errors
  2. A method has been devised whereby:
    • each dimension sheet only contains one item
    • when the taking-off is finished, dimension sheets of the same BQ item are collated and stapled together
    • squaring is done to obtain the grand total which is written on the front dimension sheet
    • short descriptions are expanded to full descriptions on the front dimension sheets
    • the dimension sheets are then shuffled according to the intended BQ sequence
    • headings are added as appropriate
    • BQ is directly typed from the dimension sheets which have headings, descriptions, unit and total quantities
  3. The number of processes is greatly reduced
  4. A drawback of this system is that when the dimension sheets are shuffled, the original sequence and logic of measurement are lost. Therefore, when the system was originally invented, the dimension sheets came together in 4 on one sheet of paper and were backed with a self impressed carbon copy. After taking-off in a logical sequence, the front sheet was taken out and cut into 4 pieces which were shuffled with other sheets. The carbon copy was kept in the original sequence to facilitate future reference
  5. 汇总卡可按清单分项次序自由排序
  6. 排序后要运算每卡总数,写在上部
  7. 总数由他人复核

Taking-off schedules 计算表

  1. Dimension sheets require descriptions against group of dimensions. To reduce writing descriptions, dimensions of all quantities of the same item should be measured in one go and this requires greater experience. For measurement of group of items which have a lot of inter-related dimensions, use of dimension sheets would be cumbersome. A schedule would be preferred
  2. The following taking-off schedule puts all items sharing the same prime data together. This enables easier understanding of their inter-relations:
    下列的计算表,把共享原始尺寸的项目并列一起计算,较容易看到互相的关系:
  3. "/" = Times 乘
  4. () = Deduct 扣减
  5. Deductions are written in red or marked with a minus sign or with brackets if photocopying is anticipated
  6. The number of columns for each set of dimensions is flexible. For items measured Cube, four columns are allocated
  7. 栏数可加减,立方项用4栏
  8. Since the width of a sheet of paper is limited, a column needs to be shared by more than one item, e.g. two types of floor finishes, and colouring of the boxes is used to distinguish dimensions for different items
  9. 因纸宽有限,可用颜色在同一组栏下表示不同的项目,加总时按颜色分开加
  10. The totals on the taking-off schedules are transferred to the dimension sheets

Direct billing

  1. With substantial portion of taking-off information given in taking-off schedule in tabulated and inter-related manner, the portion of taking-off directly on dimension sheets is greatly reduced
  2. The need for carbon copy to keep the original taking-off sequence and logic is therefore reduced
  3. "Cut" is also no longer required, one independent sheet is used for one BQ item, leaving the "shuffle" behind. Taking-off directly onto these dimension sheets which can be shuffled immediately for billing is called "direct billing"