This chapter develops the skill of preparing abstract sheets for measured quantities in civil engineering projects. Abstracting consolidates detailed measurements into summaries that guide estimation and costing. Mastery of abstracting is critical for accuracy and clarity in tender documents, bills of quantities, and project cost control. The focus is on formats, organization, application of standard methods such as SMM and CESMM, and ensuring accuracy in abstracting.

2.1 Preparation of Abstracting Sheet

The preparation of an abstracting sheet is a systematic process that transforms raw measurements into organized summaries for costing and analysis. Civil engineers in Kenya working on projects ranging from county government buildings to hospitals must ensure that abstract sheets are clear, consistent, and comply with industry standards. This section breaks down the process into key aspects: abstracting formats, organizing measurements, applying SMM/CESMM standards, and reviewing for accuracy.

2.1.1 Abstracting formats

Abstracting formats define how measured quantities are arranged and presented in a sheet. Different projects and organizations may use varied formats depending on complexity and reporting requirements.

Concept and purpose

Abstracting formats provide a structured layout that enables easy reading, verification, and transfer of data. A well-chosen format reduces errors and facilitates quick identification of quantities for costing.

Common formats used in civil engineering

1. Tabular format: Uses columns for item description, unit, quantity, and remarks. Preferred for straightforward projects.
2. Hierarchical format: Breaks down quantities by work sections and sub-sections, useful for complex projects.
3. Summary format: Presents only totals for each item or work category, often used in preliminary costing.
4. Combined format: Integrates detailed quantities with summary totals on the same sheet for comprehensive review.
5. Electronic spreadsheet format: Employs software like Excel for dynamic calculation and easy updates.

Format selection criteria

Selection depends on project complexity, client requirements, and the intended use of the abstract. For example, a county government office construction may require a hierarchical format for clarity, while a small retail shop project might use a simple tabular format.

Formatting guidelines

• Use consistent units of measurement throughout the sheet.
• Include clear headings and sub-headings.
• Ensure columns are aligned for readability.
• Leave space for cross-referencing with original measurements.
• Use page numbering and dates for document control.

Format adaptability

Formats should be adaptable to changes during project progression. Updating the abstract should not require complete reformatting but allow incremental additions or corrections.

Worked Examples

Example 1: Prepare a simple tabular abstract format for a reinforced concrete slab with measured quantities for concrete, reinforcement, and formwork.

Given:

• Concrete volume = 12 m³
• Reinforcement steel = 1.5 tonnes
• Formwork area = 80 m²

Example 2: Design a hierarchical abstract format for a 2-storey office building including foundation, walls, and roofing.

Given:

• Foundation excavation = 30 m³
• Concrete footing = 15 m³
• Wall plastering = 200 m²
• Roof covering = 150 m²

Example 3: Create an electronic spreadsheet format outline for a hospital construction project abstract including columns for item codes, description, unit, quantity, rate, and amount.

Given:

• Item codes: 101, 102, 103
• Quantities: 100 m², 50 m³, 200 kg
• Rates: Ksh 1500/m², Ksh 8000/m³, Ksh 150/kg

2.1.2 Organizing measurements for clarity

Organizing measurements effectively in an abstract sheet ensures clarity and reduces the risk of misinterpretation or errors during estimation and costing. Kenyan civil engineers often handle large volumes of data from site measurements, requiring systematic organization.

Grouping related items

Measurements should be grouped logically by trade, work section, or material type to facilitate understanding. For example, all concrete-related quantities should be together, separate from masonry or finishing works.

Sequential arrangement

Arrange items in the order of construction activities or as per the bill of quantities sequence. This helps link the abstract to the schedule of works and simplifies cross-referencing.

Use of clear headings and subheadings

Headings and subheadings should be descriptive and consistent. They guide the reader through the abstract and help locate specific items quickly.

Consistent units and decimal places

Use uniform units of measurement throughout the abstract sheet, e.g., cubic metres for volume, square metres for area. Quantities should be rounded consistently, typically to two decimal places, to balance accuracy and readability.

Inclusion of remarks and clarifications

Remarks columns provide space to note special conditions, assumptions, or references to detailed measurements. This prevents ambiguity and supports verification.

Worked Examples

Example 1: Organize the following measurements for a county government office project into a clear abstract: 15 m³ concrete, 3 tonnes reinforcement, 120 m² wall plastering, 100 m² floor tiles.

Example 2: Arrange the following items sequentially by construction process: excavation 20 m³, concrete footing 10 m³, wall blockwork 300 m², plastering 280 m².

Example 3: Organize quantities with consistent units and two decimal places: concrete 12.345 m³, steel 1.578 tonnes, plastering 85.6 m².

2.1.3 Applying SMM/CESMM standards

The Standard Method of Measurement (SMM) and Civil Engineering Standard Method of Measurement (CESMM) provide internationally recognized frameworks for measurement and abstracting. Kenyan civil engineers adopt these standards to ensure uniformity and compliance in project documentation.

Purpose of SMM and CESMM

SMM and CESMM standardize the description, measurement, and presentation of civil engineering works. They reduce ambiguity, facilitate tendering, and improve communication between contractors and clients.

Key features of SMM

1. Itemization: Work is divided into clearly defined items.
2. Units: Standard units are prescribed for each item type.
3. Measurement rules: Detailed instructions on how to measure different works.
4. Descriptions: Standardized wording for item descriptions.
5. Abstracting procedures: Guidelines for compiling measured quantities into abstracts.

Key features of CESMM

CESMM specifically addresses civil engineering works, including earthworks, concrete, drainage, and roadworks. It extends SMM principles with additional clauses for complex civil projects.

Integration in abstracting sheets

When applying SMM/CESMM, abstract sheets must follow prescribed formats and item codes. This ensures abstracts are compatible with bills of quantities and tender documents prepared under these standards.

Worked Examples

Example 1: Apply SMM rules to abstract measured quantities for concrete works: volume measured as 25 m³, unit as cubic metres, item description per SMM guidelines.

Given:

• Concrete volume = 25 m³

SMM requires:

• Item description: "Concrete in foundations and columns"
• Unit: cubic metres (m³)

Example 2: Use CESMM to abstract earthworks: excavation measured at 50 m³, unit as cubic metres, item description per CESMM.

Given:

• Excavation volume = 50 m³

CESMM requires:

• Item description: "Excavation for substructure"
• Unit: cubic metres (m³)

Example 3: Compile an abstract sheet segment applying SMM for plastering works: 100 m², unit square metres, standard description.

Given:

• Plastering area = 100 m²

SMM requires:

• Item description: "Cement and sand plaster 1:4 on walls"
• Unit: square metres (m²)

2.1.4 Reviewing abstracting accuracy

Reviewing the accuracy of abstracted quantities is essential to avoid cost overruns and disputes in Kenyan civil engineering projects. Accurate abstracts ensure that the quantities used for costing reflect actual site measurements.

Importance of review

Reviewing detects transcription errors, omissions, and inconsistencies between measurements and abstracts. It supports quality assurance before submission to clients or contractors.

Review methods

1. Cross-checking with original measurements: Verify quantities against measurement sheets or site records.
2. Consistency checks: Ensure units, item descriptions, and quantities are consistent throughout.
3. Summation verification: Confirm totals and subtotals add correctly.
4. Peer review: Have a colleague independently review the abstract sheet.
5. Use of software tools: Employ spreadsheets or specialized software to automate checks.

Common errors to detect

• Incorrect units or unit conversions.
• Missing items or duplicated quantities.
• Transcription mistakes in numbers or descriptions.
• Mismatches between abstract and bill of quantities.
• Mathematical errors in summations.

Worked Examples

Example 1: Review an abstract with concrete quantities: 15 m³ recorded, but abstract shows 12 m³. Identify and correct the error.

Given:

• Measurement sheet: 15 m³ concrete
• Abstract sheet: 12 m³ concrete

Step 1: Compare quantities
Step 2: Identify discrepancy of 3 m³
Step 3: Correct abstract quantity to 15 m³

Example 2: Check summation in an abstract sheet with quantities: 10 m³ concrete, 5 tonnes steel, 20 m² plastering. Total quantities must be correct.

Given:

• Concrete: 10 m³
• Steel: 5 tonnes
• Plastering: 20 m²

Summation check:

• Confirm individual totals match source measurements
• Verify no arithmetic errors in totals

Example 3: Use spreadsheet formula to verify totals for a set of quantities: quantities 12, 15, 8, 10 units.

Given:

• Quantities: 12, 15, 8, 10 units

Step 1: Sum quantities
Step 2: 12 + 15 = 27
Step 3: 27 + 8 = 35
Step 4: 35 + 10 = 45 units total

Compare with abstract total of 45 units for accuracy.

Chapter Summary

This chapter covers the preparation of the abstracting sheet, emphasizing the importance of selecting appropriate abstracting formats and organizing measurements clearly to enhance understanding. It outlines how to transfer item descriptions accurately from the booked measurements to the abstracting sheet while maintaining consistency and adhering to SMM and CESMM standards. The process of transferring squared quantities is detailed, highlighting the need for precise calculations and proper documentation using standard formats. Techniques for calculating net quantities are explained, including adjustments for project variations to ensure the final quantities reflect actual work done. The chapter also stresses the importance of reviewing all dimensions thoroughly, correcting errors, and verifying that measurements align precisely with project drawings. Throughout, adherence to established measurement standards and accuracy checks are underscored to maintain reliability in quantity surveying processes.