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Term 3, 2020 CVEN9723 DESIGN OF CONSTRUCTION OPERATIONS

Instructor: Dr X Shen

Date: 21 September 2020

Earthwork Estimating

Revanth

What Have We Learned?

• What is the typical estimating process?

• How to conduct the conceptual cost estimating?

• How to estimate the cost of Labour and Equipment?

Handling and Transporting Material

(Courtesy: andysearthmovers)

Learning Objectives

• How to estimate time and cost for earthmoving construction projects? • What’s quantity take-off in construction? • How to use mass diagram for grading plan? • Any technical innovations?

(Courtesy: Minesurveyor)

What’s Earthmoving?

Earthmoving is the process of moving soil or rock from one location to another and processing it so that it meets construction requirements of location, elevation, density, moisture content, etc.

Typical Earthmoving Operations

Haul, Loaded

Return, Empty

Soil Volume-Change Characteristics

Soil Conditions – Bank: natural state before disturbance

• Referred to as: “in-place” or “in-situ” • Unit: bank cubic meter (BCM)

– Loose: material that has been excavated or loaded

• Unit: loose cubic meter (LCM) – Compacted: material after compaction

• Unit: compacted cubic meter (CCM)

Soil Volume-Change Characteristics

Bank Loose Compacted (Courtesy: Nunnally 2011)

1 BCM 1.25 LCM 0.9 CCM

Load Factor

A conversion factor to simplify the conversion of loose volume to bank volume

Weight/loose unit volume

Weight/bank unit volume Load factor =

Shrinkage Factor

A factor used for the conversion of bank volume to compacted volume

Weight/bank unit volume

Weight/compacted unit volume Shrinkage factor =

Soil Volume-Change Characteristics

(Courtesy: Nunnally 2011)

Earthmoving Operations

Earthmoving Estimate

Cycle Time for Transporting Material – Loading Time – Traveling Time (haul, loaded) – Unloading Time – Returning Time (empty)

The time required for each element should be determined for cost estimate

Earthmoving Estimate

Production Rate – The number of units of work produced by a

unit of equipment or a person in a specified unit of time, e.g. m3/hour

Efficient Factor – A machine or a worker may work only 45 min

in an hour – Actual production rate is 0.75 of maximum

Earthmoving Estimate

• Production rates are crucial to estimate the time and cost of the projects • The total project time is determined by dividing the total quantity of work by the production rate • Cost of labour and equipment can be determined by multiplying the total time by the hourly rate of labour and equipment

Estimation Procedures

Step 1: Quantity of Work Step 2: Cycle Time Step 3: Production Rate Step 4: Project Time Step 5: Total Cost Step 6: Unit Cost

Example 1 A total 120 m3 of clay has to be transported to a job site 15 km away using a 10 m3 dump truck. A tractor loader is used to load the truck at a rate of 80 m3/hour. The travel times for haul and return of the truck are 32 minutes and 25 minutes, respectively. It takes 3 minutes to dump the load. The cost of the truck is $ 42 /hour, the truck driver is $ 28 /hour. The cost of the loader is $ 55 /hour, the loader operator is $ 32 /hour. The average working time is 45 minutes in one hour. Determine the total time, total cost, and the cost/unit of transporting the clay.

Productivity Improvement?

• How to improve the loading efficiency? • What is the difference using labour or a loader for loading? • How to match the number of the loader and the haul trucks?

Total Cycle Time Load Time

No. of Trucks =

Example 2

Using the data in Example 1, determine the economical number of trucks such that the load time and transport time balance.

Productivity Improvement?

What if there are 2 loaders and 10 trucks? How to estimate the project cost?

(Courtesy: CYCLONE Simulation)

Earthwork Quantity Take-off

(Courtesy: Donaldson Garrett)

Earthwork Quantity Take-off

• When planning or estimating an earthmoving project, it is often necessary to estimate the volume of material to be excavated or placed (Cut vs. Fill) • Quantity take-off is a detailed measurement of earthwork volume to complete a construction project

Earthwork Quantity Take-off

• Contractors are paid for the volume of excavation • Earthwork can be roughly estimated by counting the number of truckloads

(Courtesy: CAT)

Pit Excavations

Small, relatively deep excavations Volume = Horizontal area × Average depth

(Courtesy: FictionU)

Pit Excavations

Calculation – Step 1: Divide the horizontal area into a

convenient set of rectangles, triangles, or circular segments

– Step 2: Determine the total area as the sum of the segment areas

– Step 3: Calculate the average depth

Example 3 Estimate the volume of excavation required for the basement. Values shown at each corner are depths of excavation.

(Courtesy: Nunnally 2011)

Trench Excavations Usually constructed for utility lines

Volume = Cross-sectional area × Length

(Courtesy: Joyceroad)

Example 4 Find the volume of excavation required for a trench 0.92 m wide, 1.83 m deep, and 152 m long. Assume that the trench sides will be approximately vertical.

(Courtesy: ecmweb)

Large Areas Dividing the area into a grid indicating the depth of excavation or fill at each grid intersection

(Courtesy: wplinternational)

Large Areas

(Courtesy: CAT)

Large Areas

Average Depth – Assign the depth at each corner or segment

intersection a weight according to its location • Interior points: Weight of four • Exterior points at the intersection of two

segments: Weight of two • Corner point: Weight of one

Large Areas

Average Depth

Sum of products of depth × Weight

Sum of weight =

Example 5

Mass Diagram

(Courtesy: ugpti.org)

Mass Diagram

• A continuous curve representing the accumulated volume of earthwork plotted against the linear profile of a roadway or airfield • Prepared by highway and airfield designers

Mass Diagram

• Used to assist in selecting an alignment which minimizes the earthwork required to construct the facility while meeting established limits of roadway grade and curvature • Very useful for construction manager

Example 6

37 (Courtesy: Nunnally 2011)

(Courtesy: Nunnally 2011)

Innovations in Earthmoving

(Courtesy: aerometrex)

Aerial Innovation

(Courtesy: THIESS)

UAV Resources at UNSW

Multirotor UAVs

DJI Phantom 3 Professional • Weight: 1.28 Kg • Sensor: 12MP Camera • Flight time: 20 min • No. of Propellers: 4

Vulcan Heavy Lift Octocopter • Weight: 14 Kg • Sensors: LiDAR/Infrared Cam • Flight time: 1 Hour • No. of Propellers: 8

UAV Resources at UNSW

Fixed Wing UAVs

SenseFly eBee RTK • Weight: 0.73 kg • Sensor: 12MP RGB & NIR Cams • Flight time: 40 min • Wingspan: 0.96 m

SenseFly swinglet CAM • Weight: 0.5 kg • Sensors: 12 MP Camera • Flight time: 30 min • Wingspan: 0.8 m

Learning Objectives

• How to estimate time and cost for earthmoving construction projects? • What’s quantity take-off in construction? • How to use mass diagram for grading plan? • Any technical innovations?

(Courtesy: Minesurveyor)

Questions?