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Lecture 13-1. Geometric Highway Design – Spring 2007 

Lecture Week 13-1QUANTITY ESTIMATION & MASS-HAUL DIAGRAMS

TOPICS

 – Quantity Estimates

 – Earthworks Quantities• End-Area Calculations

• Shrink and Swell

• Interpreting Mass-Haul Diagrams

 – Mass Haul Diagrams

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Lecture 13-1. Geometric Highway Design – Spring 2007 

Cost Estimation

• The highway design process often requires thedesigner to consider a number of constraints before

arriving at a balanced design.• In most cases, the balanced design is only achievedafter several iterations have been completed.

• Political, social, environmental and economical forceswill interplay when a project is in the design stage.

• The effectiveness of a design alignment is measured

using a number of methods.• One measurement tool which assists the designer to

estimate the economic implications of a project is

known as cost estimation.

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Lecture 13-1. Geometric Highway Design – Spring 2007 

Cost Estimation

• Estimates can be calculated using various levels ofdetail.

• A simple model may have global estimates for roadconstruction (e.g. $1.2 million / km of two-lane-two-way highway, 110 km/h design speed), and other

components of the project ($5 million per fullydirectional interchange). This model may be mostappropriate during the preliminary design process.

• As a project progresses, a more detailed estimate isnormally required.

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Sample of Items to Quantify

• Right of way acquisition

• Clearing

• Grubbing

• Stripping• In-situ material excavation

• Fill placement

• Erosion Control material• Drainage infrastructure

• Granular materials

• Paving• Signing

• Lighting

• Landscaping

• Maintenance of traffic during construction

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Preliminary Cost Estimate

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Cost Estimation

• One of the costliest items in the previous list is the excavation(and placement) of existing material. Cut material, if of adequatequality, is used to fill those locations where the existing elevation

of the ground is below the design grade.• The estimation of the quantity of material which must be

excavated (cut), and the quantity of material required to raise the

elevation of the existing ground (fill), is very useful in thedevelopment of a cost estimate for a project.

• The final cross-section and alignment characteristics of theroadway are often adjusted to bring the two quantities to

unity. Stockpiling extra material or importing additional materialare additional costs which can be avoided if the cut and fillquantities are in balance.

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Quantity of Material

• Most of the other quantities listed previously are tieddirectly to the cut an fill estimates. The compilation oftheir estimates and combination with unit costs, enables

the designer to arrive at an overall cost for the project.• When construction projects are publicly tendered,

quantity estimates are often part of the information

 provided to contractors who bid to complete thework. Quantity estimation by computer has providedmarginal improvements to the accuracy of estimates

• However, its greater benefit has been to give designersthe ability to consider multiple design alternatives inmore detail which, in turn, enables them to arrive at

 better design.

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Calculating Quantities

The cross-section of the fill at three points, 1, 2, and 3,is shown. The areas ofthe fill cross-sections, A1, A2, and A3, are also shown. The "cross sectional"area of the amount of fill would be measured at standard points, or "station",along the alignment. The distance between sections is normally constant. The

volume of fill material between Section 1 and Section 2 can be calculated usingthe "Average-End-Area" method as represented by the formula:

V = ((A1 + A2)/2)*L

Where:

V = volume of material between Stations 1 and 2

with fill end-areas A1 and

A2

L = segment length (inmeters)

V = volume (m3), and

A1 and A2 are end areas

(m2)

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Shrink and Swell

Excavated in-situ material used in embankments or fillsmay swell or shrink. It is important to determine the

 properties of a material in order to evaluate how these properties will affect the earthwork volume estimates.

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Lecture 13-1. Geometric Highway Design – Spring 2007 

Shrinkage

• When earth is excavated and hauled for use ascompacted fill, its volume once compacted is normallyless than its original condition before it was excavated.

This difference is defined as “shrinkage”.• The amount of shrinkage will depend on the type ofmaterial used.

• A shrinkage factor, or compaction factor, of 10 to 15 percent is common. Dense in-situ materials may besomewhat lower.

• Shrinkage of 40 to 50 percent for some types of materialis possible. These high shrinkage values also accountfor other factors, such as loss of material in the hauling

 process and loss of material at the toe of a

slope. Shrinkage should not include settlement of fillsdue to consolidation.

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Lecture 13-1. Geometric Highway Design – Spring 2007 

Swell

• When rock is excavated and placed in a fill, the materialwill occupy a larger volume due to the air voids that areintroduced into the material.

• This increase is called 'swell' or 'bulking'.• Swell can be as high as 40 percent.

• Swell is only taken into account when a rock fill is

 being considered.• Swell is not considered for small amounts of loose rock

or boulders placed in an embankment

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Lecture 13-1. Geometric Highway Design – Spring 2007 

MASS-HAUL DIAGRAMS & DECISION TABLES

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Lecture 13-1. Geometric Highway Design – Spring 2007 

Mass Haul Diagram

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Lecture 13-1. Geometric Highway Design – Spring 2007 

Mass-Haul Diagrams

• A Mass-haul diagram is a useful method tographically represent the amount of material thatwill be cut and used for fill on any earthwork

 job, particularly for highway or railway projects.• It illustrates the location of the mass balance points, the direction of haul, and the amount ofearth to be taken to or from any location alongthe alignment.

• Mass diagrams are also extremely useful indetermining the most economical distribution ofmaterial.

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Lecture 13-1. Geometric Highway Design – Spring 2007 

Mass-Haul Definitions

• Excavation (E) Excavation refers to any materialremoved from its original location. Excavation iscommonly split into two categories - ordinary material

(OM) and rock. Both OM and rock are generallycalculated by volume (cubic yard or meter) and costedin this manner; that is, in $/yd3 or $/m3. These twoquantities are normally handled as a separate cost items

 because rock is substantially more expensive toexcavate.

• Occasionally, the estimator may not classify the

material separately and attribute a cost to the totalvolume of material. This might be the case wheregeotechnical information is not complete enough toaccurately assess the depth of bedrock, or if rock in thearea can be easily excavated without blasting.

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Lecture 13-1. Geometric Highway Design – Spring 2007 

Mass-Haul Definitions

• Free haul (F) When material is excavated, constructioncontractors will normally move it over an establisheddistance free of charge. This distance is the "free haul",

and is normally agreed upon between the client and builder.

• Overhaul (O) Overhaul is defined as the distance overwhich the excavated material must be hauled, less thefree haul distance. The cost for overhaul is normallyspecified by the contractor. This rate is normally givenin $/yd3/unit-distance or $/m3/unit-distance .

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Lecture 13-1. Geometric Highway Design – Spring 2007 

Mass-Haul Definitions

• Borrow (B) Borrow refers to the fill material that must be brought to the proposed highway site from outsidethe highway corridor. Borrow does not include the

material that is excavated on site for use as fill . The borrow cost is normally given $/yd3 or $/m3, and thisrate normally includes the cost of excavating andtransporting borrow.

• Limit of Economic Overhaul (L) The limit ofeconomic overhaul is a distance beyond which it is not

economic to overhaul. At this point, the cost toexcavate and overhaul on-site material is equal to thecost of excavating and delivering borrowed material.

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Lecture 13-1. Geometric Highway Design – Spring 2007 

Mass-Haul Definitions

• Waste (W) Waste is the excavated material that cannot be used for fill on the project site. Normally, thedesigner will try to roughly balance the amount of cut

and fill required on a project at the design stage, so thatthe amount of fill that must be transported in (borrow)or the amount of waste that must be hauled away are notexcessive. Waste can also include excavated materials

that are unsuitable for use as a fill because they haveunacceptable engineering properties (such as peat, clays,etc.). Sometimes it is more economical to waste

material and use borrow material from a borrow pit. This occurs where it is necessary to haul excavatedmaterial long distances to use as fill.

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Lecture 13-1. Geometric Highway Design – Spring 2007 

Properties of Mass-Haul Diagrams

• The ordinate at any point of the curve of a mass haul diagram isthe cumulative volume of material from the initial project stationto that point.

• The rate of excavation/placement is indicated by the slope

curve. A rising curve indicates a cut; a falling curve indicates afill.

• Where the earthwork changes from a cut to a fill, or a fill to a cut,the slope of the curve is 0.

a = volume of borrow required

b = locations where borrowed is requiredc = volume of waste = location where waste will occur.

Balanced section

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Lecture 13-1. Geometric Highway Design – Spring 2007 

Properties of Mass-Haul Diagrams

• Any horizontal line which joins points on the curve where balance is achieved is called a balance line. Balance lines neednot be continuous. In most cases, the free haul distance or thelimit of economic overhaul are established and plotted on the

mass haul diagram.• A vertical break between any two balance lines indicates an area

where balance does not occur. At these breaks a shortfall orexcess material exists. The location and volume of waste or

 borrow can be determined in this manner.

a = volume of borrow required

b = location where borrowed is required

c = volume of wasted = location where waste will occur.

Balanced section

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Lecture 13-1. Geometric Highway Design – Spring 2007 

Properties of Mass-Haul Diagrams

F = freehaul

O = overhaul

W = wasteB = borrow

L = limit of economic overhaul