Project Management for Construction_ Organization and Use of Project Information

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Go Up to Table of Contents

Go To Chapter 13

(Quality Control and

Safety During

Construction)

Go To Chapter 14

(Organization and

Use of Project

Information)

Organization and Use of Project

Information

Types of Project Information

Accuracy and Use of Information

Computerized Organization and Use of

Information

Organizing Information in Databases Relational Model of Databases

Other Conceptual Models of Databases

Centralized Database Management

Systems

Databases and Applications Programs

Information Transfer and Flow

References

Problems

Footnotes

14. Organization and Use of Project Information

14.1 Types of Project Information

Construction projects inevitably generate enormous and complex sets of information. Effectively managing this

bulk of information to insure its availability and accuracy is an important managerial task. Poor or missing

information can readily lead to project delays, uneconomical decisions, or even the complete failure of the

desired facility. Pity the owner and project manager who suddenly discover on the expected delivery date that

important facility components have not yet been fabricated and cannot be delivered for six months! With better

information, the problem could have been identified earlier, so that alternative suppliers might have been located

or schedules arranged. Both project design and control are crucially dependent upon accurate and timely

information, as well as the ability to use this information effectively. At the same time, too much unorganized

information presented to managers can result in confusion and paralysis of decision making.

As a project proceeds, the types and extent of the information used by the various organizations involved will

change. A listing of the most important information sets would include:

cash flow and procurement accounts for each organization,

intermediate analysis results during planning and design,

design documents, including drawings and specifications,

construction schedules and cost estimates,quality control and assurance records,

chronological files of project correspondence and memorandum,

construction field activity and inspection logs,

legal contracts and regulatory documents.

Some of these sets of information evolve as the project proceeds. The financial accounts of payments over the

entire course of the project is an example of overall growth. The passage of time results in steady additions in

these accounts, whereas the addition of a new actor such as a contractor leads to a sudden jump in the number

of accounts. Some information sets are important at one stage of the process but may then be ignored. Common

examples include planning or structural analysis databases which are not ordinarily used during construction or

operation. However, it may be necessary at later stages in the project to re-do analyses to consider desired

changes. In this case, archival information storage and retrieval become important. Even after the completion of

construction, an historical record may be important for use during operation, to assess responsibilities in case of

facility failures or for planning similar projects elsewhere.

The control and flow of information is also important for collaborative work environments, where manyprofessionals are working on different aspects of a project and sharing information. Collaborative work

environments provide facilities for sharing datafiles, tracing decisions, and communication via electronic mail or

video conferencing. The datastores in these collaborative work environments may become very large.

Based on several construction projects, Maged Abdelsayed of Tardif, Murray & Assoc (Quebec, Canada)

estimated the following average figures for a typical project of US$10 million:

Number of participants (companies): 420 (including all suppliers and sub-sub-contractors)

Number of participants (individuals): 850

Number of different types of documents generated: 50

Number of pages of documents: 56,000

Number of bankers boxes to hold project documents: 25

Number of 4 drawers filin cabinets: 6

12/11/2010 Project Management for Construction:

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While there may be substantial costs due to inaccurate or missing information, there are also significant costs

associated with the generation, storage, transfer, retrieval and other manipulation of information. In addition to the

costs of clerical work and providing aids such as computers, the organization and review of information

command an inordinate amount of the attention of project managers, which may be the scarcest resource on any

construction project. It is useful, therefore, to understand the scope and alternatives for organizing project

information.

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14.2 Accuracy and Use of Information

Numerous sources of error are expected for project information. While numerical values are often reported to

the nearest cent or values of equivalent precision, it is rare that the actual values are so accurately known. Livingwith some uncertainty is an inescapable situation, and a prudent manager should have an understanding of the

uncertainty in different types of information and the possibility of drawing misleading conclusions.

We have already discussed the uncertainty inherent in making forecasts of project costs and durations sometime

in the future. Forecast uncertainty also exists in the short term. For example, consider estimates of work

completed. Every project manager is familiar with situations in which the final few bits of work for a task take an

inordinate amount of time. Unforeseen problems, inadequate quality on already completed work, lack of

attention, accidents, or postponing the most difficult work problems to the end can all contribute to making the

final portion of an activity actually require far more time and effort than expected. The net result is that estimates

of the actual proportion of work completed are often inaccurate.

Some inaccuracy in reports and estimates can arise from conscious choices made by workers, foremen or

managers. If the value of insuring accuracy is thought to be low or nonexistent, then a rational worker will not

expend effort or time to gather or to report information accurately. Many project scheduling systems flounder on

exactly this type of non-reporting or mis-reporting. The original schedule can quickly become extremely

misleading without accurate updating! Only if all parties concerned have specific mandates or incentives to reportaccurately will the data be reliable.

Another source of inaccuracy comes from transcription errors of various sorts. Typographical errors, incorrect

measurements from reading equipment, or other recording and calculation errors may creep into the sets of

information which are used in project management. Despite intensive efforts to check and eliminate such errors,

their complete eradication is virtually impossible.

One method of indicating the relative accuracy of numerical data is to report ranges or expected deviations of an

estimate or measurement. For example, a measurement might be reported as 198 ft. + 2 ft. There are two

common interpretations of these deviations. First, a range (such as + 2) might be chosen so that the actual value

is certain to be within the indicated range. In the case above, the actual length would be somewhere between

196 and 200 feet with this convention. Alternatively, this deviation might indicate the typicalrange of the estimate

or measurement. In this case, the example above might imply that there is, say, a two-thirds chance that the

actual length is between 196 and 200.

When the absolute range of a quantity is very large or unknown, the use of a statistical standard deviation as a

measure of uncertainty may be useful. If a quantity is measured n times resulting is a set of values x i (i = 1,2,...,n),

then the average or mean value then the average or mean value is given by:

(14.1)

The standard deviation can be estimated as the square root s of the sample variance s2, i.e. , where:

(14.2)

The standard deviation is a direct indicator of the spread or variability in a measurement, in the same units as

the measurement itself. Higher values of the standard deviation indicate greater and greater uncertainty about theexact value of the measurement. For the commonly encountered normal distribution of a random variable, the

average value plus or minus one standard deviation, + , will include about two-thirds ofx the actual

occurrences. A related measure of random variability is the coefficient of variation, defined as the ratio of the

standard deviation to the mean:

(14.3)

Thus, a coefficient of variation indicates the variability as a proportion of the expected value. A coefficient of

variation equal to one (c = 1) represents substantial uncertainty, whereas a value such as c = 0.1 or ten percent

indicates much smaller variability.




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interpreting recorded information without involving any conceptual understanding of how the information is

actually gathered, stored and recorded or how work on the project actually proceeds.

Example 14-1: Sources of Delay and Cost Accounts

It is common in construction activity information to make detailed records of costs incurred and

work progress. It is less common to keep detailed records of delays and their causes, even though

these delays may be the actual cause of increased costs and lower productivity. [1] Paying

exclusive attention to costaccounts in such situations may be misleading. For example, suppose that

the accounts for equipment and material inventories show cost savings relative to original estimates,

whereas the costs associated with particular construction activities show higher than estimated

expenditures. In this situation, it is not necessarily the case that the inventory function is performing

well, whereas the field workers are the cause of cost overrun problems. It may be that construction

activities are delayed by lack of equipment or materials, thus causing cost increases. Keeping alarger inventory of materials and equipment might increase the inventory account totals, but lead to

lower overall costs on the project. Better yet, more closely matching demands and supplies might

reduce delay costs without concurrent inventory cost increases. Thus, simply examining cost

account information may not lead to a correct diagnosis of a problem or to the correct managerial

responses.

Example 14-2: Interest Charges

Financial or interest charges are usually accumulated in a separate account for projects, while the

accounts associated with particular activities represent actual expenditures. For example, planning

activities might cost $10,000 for a small project during the first year of a two year project. Since

dollar expenditures have a time value, this $10,000 cost in year 1 is notequivalent in value to a

$10,000 cost in year 2. In particular, financing the early $10,000 involves payment of interest or,

similarly, the loss of investment opportunities. If the borrowing rate was 10%, then financing the first

year $10,000 expenditure would require $10,000 x 0.10 = $1,000 and the value of the expenditure

by the end of the second year of the project would be $11,000. Thus, some portion of the overallinterest charges represents a cost associated with planning activities. Recognizing the true value of

expenditures made at different periods of time is an important element in devising rational planning

and management strategies.

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14.3 Computerized Organization and Use of Information

Numerous formal methods and possible organizations exist for the information required for project management.

Before discussing the details of computations and information representation, it will be useful to describe a record

keeping implementation, including some of the practical concerns in design and implementation. In this section,

we shall describe a computer based system to provide construction yard and warehouse management

information from the point of view of the system users. [2] In the process, the usefulness of computerized

databases can be illustrated.

A yard or warehouse is used by most construction firms to store equipment and to provide an inventory of

materials and parts needed for projects. Large firms may have several warehouses at different locations so as to

reduce transit time between project sites and materials supplies. In addition, local "yards" or "equipment sheds"

are commonly provided on the job site. Examples of equipment in a yard would be drills, saws, office trailers,

graders, back hoes, concrete pumps and cranes. Material items might include nails, plywood, wire mesh, forming

lumber, etc.

In typical construction warehouses, written records are kept by warehouse clerks to record transfer or return of

equipment to job sites, dispatch of material to jobs, and maintenance histories of particular pieces of equipment.

In turn, these records are used as the basis for billing projects for the use of equipment and materials. For

example, a daily charge would be made to a project for using a concrete pump. During the course of a month,

the concrete pump might spend several days at different job sites, so each project would be charged for its use.

The record keeping system is also used to monitor materials and equipment movements between sites so that

equipment can be located.

One common mechanism to organize record keeping is to fill out cards recording the transfer of items to or from

a job site. Table 14-1 illustrates one possible transfer record. In this case, seven items were requested for the

Carnegie-Mellon job site (project number 83-1557). These seven items would be loaded on a delivery truck,along with a copy of the transfer record. Shown in Table 14-1 is a code number identifying each item (0609.02,

0609.03, etc.), the quantity of each item requested, an item description and a unit price. For equipment items, an

equipment number identifying the individual piece of equipment used is also recorded, such as grinder No. 4517

in Table 14-1; a unit price is not specified for equipment but a daily rental charge might be imposed.

TABLE 14-1 Illustration of a Construction Warehouse Transfer Record

TRANSFER SHEET NUMBER 100311

Deliver To: Carnegie-Mellon

Received From: Pittsburgh Warehouse

Job. No. 83-1557

Job No. 99-PITT

ITEM NO. EQ. NO. QTY DESCRIPTION UNIT PRICE




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0996.01

0607.03

0172.00

0181.53

4517

3

4

1

1

Paint, Spray

Plywood, 4 x 8 x 1/4"

Grinder

Grinding Wheel, 6" Cup

5.57

11.62

14.97

Preparer: Vicki Date: x/xx/xx

Transfer sheets are numbered (such as No. 100311 in Table 14-1), dated and the preparer identified to facilitate

control of the record keeping process. During the course of a month, numerous transfer records of this type are

accumulated. At the end of a month, each of the transfer records is examined to compile the various items or

equipment used at a project and the appropriate charges. Constructing these bills would be a tedious manualtask. Equipment movements would have to be tracked individually, days at each site counted, and the daily

charge accumulated for each project. For example, Table 14- 1 records the transfer of grinder No. 4517 to a job

site. This project would be charged a daily rental rate until the grinder was returned. Hundreds or thousands of

individual item transfers would have to be examined, and the process of preparing bills could easily require a

week or two of effort.

In addition to generating billing information, a variety of reports would be useful in the process of managing a

company's equipment and individual projects. Records of the history of use of particular pieces of equipment are

useful for planning maintenance and deciding on the sale or scrapping of equipment. Reports on the cumulative

amount of materials and equipment delivered to a job site would be of obvious benefit to project managers.

Composite reports on the amount, location, and use of pieces of equipment of particular types are also useful in

making decisions about the purchase of new equipment, inventory control, or for project planning. Unfortunately,

producing each of these reports requires manually sifting through a large number of transfer cards. Alternatively,

record keeping for these specific projects could have to proceed by keeping multiple records of the same

information. For example, equipment transfers might be recorded on (1) a file for a particular piece of equipment

and (2) a file for a particular project, in addition to the basic transfer form illustrated in Table 14-1. Even withthese redundant records, producing the various desired reports would be time consuming.

Organizing this inventory information in a computer program is a practical and desirable innovation. In addition to

speeding up billing (and thereby reducing borrowing costs), application programs can readily provide various

reports orviews of the basic inventory information described above. Information can be entered directly to the

computer program as needed. For example, the transfer record shown in Table 14-1 is based upon an input

screen to a computer program which, in turn, had been designed to duplicate the manual form used prior to

computerization. Use of the computer also allows some interactive aids in preparing the transfer form. This type

of aid follows a simple rule: "Don't make the user provide information that the system already knows." [3] In

using the form shown in Table 14-1, a clerk need only enter the code and quantity for an item; the verbal

description and unit cost of the item then appear automatically. A copy of the transfer form can be printed locally,

while the data is stored in the computer for subsequent processing. As a result, preparing transfer forms and

record keeping are rapidly and effectively performed.

More dramatically, the computerized information allows warehouse personnel both to ask questions about

equipment management and to readily generate the requisite data for answering such questions. The records of

transfers can be readily processed by computer programs to develop bills and other reports. For example,

proposals to purchase new pieces of equipment can be rapidly and critically reviewed after summarizing the

actual usage of existing equipment. Ultimately, good organization of information will typically lead to the desire to

store new types of data and to provide new views of this information as standard managerial tools.

Of course, implementing an information system such as the warehouse inventory database requires considerable

care to insure that the resulting program is capable of accomplishing the desired task. In the warehouse inventory

system, a variety of details are required to make the computerized system an acceptable alternative to a long

standing manual record keeping procedure. Coping with these details makes a big difference in the system's

usefulness. For example, changes to the status of equipment are generally made by recording transfers as

illustrated in Table 14-1. However, a few status changes are not accomplished by physical movement. One

example is a charge for air conditioning in field trailers: even though the air conditioners may be left in the field,

the construction project should not be charged for the air conditioner after it has been turned off during the cold

weather months. A special status change report may be required for such details. Other details of record keeping

require similar special controls.

Even with a capable program, simplicity of design for users is a critical factor affecting the successfulimplementation of a system. In the warehouse inventory system described above, input forms and initial reports

were designed to duplicate the existing manual, paper-based records. As a result, warehouse clerks could readily

understand what information was required and its ultimate use. A good rule to follow is the Principle of Least

Astonishment: make communications with users as consistent and predictable as possible in designing programs.

Finally, flexibility of systems for changes is an important design and implementation concern. New reports or

views of the data is a common requirement as the system is used. For example, the introduction of a new

accounting system would require changes in the communications procedure from the warehouse inventory system

to record changes and other cost items.

In sum, computerizing the warehouse inventory system could save considerable labor, speed up billing, and

facilitate better management control. Against these advantages must be placed the cost of introducing computer




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14.4 Organizing Information in Databases

Given the bulk of information associated with construction projects, formal organization of the information is

essential so as to avoid chaos. Virtually all major firms in the arena of project management have computer based

organization of cost accounts and other data. With the advent of micro-computer database managers, it is

possible to develop formal, computerized databases for even small organizations and projects. In this section, we

will discuss the characteristics of such formal databases. Equivalent organization of information for manual

manipulation is possible but tedious. Computer based information systems also have the significant advantage of

rapid retrieval for immediate use and, in most instances, lower overall costs. For example, computerized

specifications writing systems have resulted in well documented savings. These systems have records of common

specification phrases or paragraphs which can be tailored to specific project applications. [4]

Formally, a database is a collection of stored operational information used by the management and application

systems of some particular enterprise. [5] This stored information has explicit associations or relationships

depending upon the content and definition of the stored data, and these associations may themselves be

considered to be part of the database. Figure 14-1 illustrates some of the typical elements of a database. The

internal modelis the actual location and representation of the stored data. At some level of detail, it consists of

the strings of "bits" which are stored in a computer's memory, on the tracks of a recording disk, on a tape, or on

some other storage device.

Figure 14-1 Illustration of a Database Management System Architecture

A manager need not be concerned with the details of data storage since this internal representation and

manipulation is regulated by theDatabase Manager Program (DBM). The DBM is the software program that

directs the storage, maintenance, manipulation and retrieval of data. Users retrieve or store data by issuing

specific requests to the DBM. The objective of introducing a DBM is to free the user from the detail of exactly

how data are stored and manipulated. At the same time, many different users with a wide variety of needs can

use the same database by calling on the DBM. Usually the DBM will be available to a user by means of a special

query language. For example, a manager might ask a DBM to report on all project tasks which are scheduled tobe underway on a particular date. The desirable properties of a DBM include the ability to provide the user with

ready access to the stored data and to maintain the integrity and security of the data. Numerous commercial

DBM exist which provide these capabilities and can be readily adopted to project management applications.

While the actual storage of the information in a database will depend upon the particular machine and storage

media employed, a Conceptual Data Modelexists which provides the user with an idea or abstract

representation of the data organization. (More formally, the overall configuration of the information in the

database is called the conceptual schema.) For example, a piece of data might be viewed as a particular value

within a recordof a datafile. In this conceptual model, a datafile for an application system consists of a series of

records with pre-defined variables within each record. A record is simply a sequence of variable values, which

may be text characters or numerals. This datafile model is one of the earliest and most important data

organization structures. But other views of data organization exist and can be exceedingly useful. The next section




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database. In some systems, data dictionaries are limited to descriptions of the items in the database. More

general systems employ the data dictionary as the information source for anything dealing with the database

systems. It documents the design of the database: what data are stored, how the data is related, what are the

allowable values for data items, etc. The data dictionary may also contain user authorizations specifying who may

have access to particular pieces of information. Another important element of the data dictionary is a specification

of allowable ranges for pieces of data; by prohibiting the input of erroneous data, the accuracy of the database

improves.

External models are the means by which the users view the database. Of all the information in the database, one

particular user's view may be just a subset of the total. A particular view may also require specific translation or

manipulation of the information in the database. For example, the external modelfor a paycheck writing

program might consist solely of a list of employee names and salary totals, even if the underlying database would

include employee hours and hourly pay rates. As far as that program is concerned, no other data exists in the

database. The DBM provides a means of translating particular external models or views into the overall datamodel. Different users can view the data in quite distinct fashions, yet the data itself can be centrally stored and

need not be copied separately for each user. External models provide the format by which any specific

information needed is retrieved. Database "users" can be human operators or other application programs such as

the paycheck writing program mentioned above.

Finally, theDatabase Administratoris an individual or group charged with the maintenance and design of the

database, including approving access to the stored information. The assignment of the database administrator

should not be taken lightly. Especially in large organizations with many users, the database administrator is vital to

the success of the database system. For small projects, the database administrator might be an assistant project

manager or even the project manager.

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14.5 Relational Model of Databases

As an example of how data can be organized conceptually, we shall describe the relational data model. In thisconceptual model, the data in the database is viewed as being organized into a series ofrelations or tables of

data which are associated in ways defined in the data dictionary. A relation consists of rows of data with columns

containing particular attributes. The term "relational" derives from the mathematical theory of relations which

provides a theoretical framework for this type of data model. Here, the terms "relation" and data "table" will be

used interchangeably. Table 14-2 defines one possible relation to record unit cost data associated with particular

activities. Included in the database would be one row (or tuple) for each of the various items involved in

construction or other project activities. The unit cost information associated with each item is then stored in the

form of the relation defined in Table 14-2.

TABLE 14-2 Illustration of a Relation Description: Unit Price Information Attributes

Attribute Name Attribute Description Attribute Type Key

ITEM_CODE

DESCRIPTION

WORK_UNIT

CREW_CODE

OUTPUT

TIME_UNIT

MATL_UNIT_COST

DATEMCOS

INSTCOST

DATEICOS

Item Code Number

Item Description

Standard Unit of

Work for the Item

Standard Crew Code for Activity

Average Productivity of Crew

Standard Unit of OUTPUT

Material Unit Cost

Date of MATL_UNIT_COST

Installation Unit Cost

Date of INSTCOST

Pre-defined Code

Text

Text

(restricted to allowable units)

Pre-defined Code

Numerical

Text

Numerical

Date Text

Numerical

Date Text

Yes

No

No

No

No

No

No

No

No

No

Using Table 14-2, a typical unit cost entry for an activity in construction might be:

ITEM_CODE: 04.2-66-025

DESCRIPTION: common brick masonry, 12" thick wall, 19.0 bricks per S.F.

WORK_UNIT: 1000 bricks

CREW_CODE: 04.2-3

OUTPUT: 1.9

TIME_UNIT: Shift

MATL_UNIT_COST: 124

DATEMCOS: June-09-79

INSTCOST: 257

DATEICOS: August-23-79

This entry summarizes the unit costs associated with construction of 12" thick brick masonry walls, as indicated

by the item DESCRIPTION. The ITEM_CODE is a numerical code identifying a particular activity. This code

might identify general categories as well; in this case, 04.2 refers to general masonry work. ITEM_CODE might

be based on the MASTERFORMAT or other coding scheme. The CREW_CODE entry identifies the standard

crew which would be involved in the activity. The actual composition of the standard crew would be found in a

CREW RELATION under the entry 04.2-3, which is the third standard crew involved in masonry work (04.2).




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WORK_UNIT, OUTPUT and TIME_UNIT summarize the expected output for this task with a standard crew

and define the standard unit of measurement for the item. In this case, costs are given per thousand bricks per

shift. Finally, material (MATL_UNIT_COST) and installation (INSTCOSTS) costs are recorded along with the

date (DATEMCOS and DATEICOS) at which the prices were available and entered in the database. The date

of entry is useful to insure that any inflation in costs can be considered during use of the data.

The data recorded in each row could be obtained by survey during bid preparations, from past project

experience or from commercial services. For example, the data recorded in the Table 14-2 relation could be

obtained as nationwide averages from commercial sources.

An advantage of the relational database model is that the number of attributes and rows in each relation can be

expanded as desired. For example, a manager might wish to divide material costs (MATL_UNIT_COST) into

attributes for specific materials such as cement, aggregate and other ingredients of concrete in the unit costrelation defined in Table 14-2. As additional items are defined or needed, their associated data can be entered in

the database as another row (or tuple) in the unit cost relation. Also, new relations can be defined as the need

arises. Hence, the relational model of database organization can be quite flexible in application. In practice, this is

a crucial advantage. Application systems can be expected to change radically over time, and a flexible system is

highly desirable.

With a relational database, it is straightforward to issue queries for particular data items or to combine data from

different relations. For example, a manager might wish to produce a report of the crew composition needed on a

site to accomplish a given list of tasks. Assembling this report would require accessing the unit price information

to find the standard crew and then combining information about the construction activity or item (eg. quantity

desired) with crew information. However, to effectively accomplish this type of manipulation requires the

definition of a "key" in each relation.

In Table 14-2, the ITEMCODE provides a unique identifier orkey for each row. No other row should have the

same ITEMCODE in any one relation. Having a unique key reduces the redundancy of data, since only one row

is included in the database for each activity. It also avoids error. For example, suppose one queried the database

to find the material cost entered on a particular date. This response might be misleading since more than onematerial cost could have been entered on the same date. Similarly, if there are multiple rows with the same

ITEMCODE value, then a query might give erroneous responses if one of the rows was out of date. Finally, each

row has only a single entry for each attribute. [6]

The ability to combine or separate relations into new arrangements permits the definition of alternative views or

external models of the information. Since there are usually a number of different users of databases, this can be

very useful. For example, the payroll division of an organization would normally desire a quite different

organization of information about employees than would a project manager. By explicitly defining the type and

organization of information a particular user group or application requires, a specific view or subset of the entire

database can be constructed. This organization is illustrated in Fig. 14-1 with the DATA DICTIONARY serving

as a translator between the external data models and the database management system.

Behind the operations associated with querying and manipulating relations is an explicit algebraic theory. This

algebra defines the various operations that can be performed on relations, such as union (consisting of all rows

belonging to one or the other of two relations), intersection (consisting of all rows belonging to both of two

relations), minus (consisting of all rows belonging to one relation and not another), or projection (consisting of asubset of the attributes from a relation). The algebraic underpinnings of relational databases permits rigorous

definitions and confidence that operations will be accomplished in the desired fashion. [7]

Example 14-3: A Subcontractor Relation

As an illustration of the preceding discussion, consider the problem of developing a database of

possible subcontractors for construction projects. This database might be desired by the cost

estimation department of a general contractor to identify subcontractors to ask to bid on parts of a

project. Appropriate subcontractors appearing in the database could be contacted to prepare bids

for specific projects. Table 14-3 lists the various attributes which might be required for such a list

and an example entry, including the subcontractor's name, contact person, address, size (large,

medium or small), and capabilities.

TABLE 14-3 Subcontractor Relation Example

Attribute Example

NAMECONTACT

PHONE

STREET

CITY

STATE

ZIPCODE

SIZE

CONCRETE

ELECTRICAL

MASONRY

etc.

XYZ Electrical Co.Betty XYZ

(412) xxx-xxxx

xxx Mulberry St.

Pittsburgh

PA

152xx

large

no

yes

no




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To use this relation, a cost estimator might be interested in identifying large, electrical subcontractors

in the database. A query typed into the DBM such as:

SELECT from SUBCONTRACTORS

where SIZE = Large and ELECTRICAL = Yes

would result in the selection of all large subcontractors performing electrical work in the

subcontractor's relation. More specifically, the estimator might want to find subcontractors in a

particular state:

SELECT from SUBCONTRACTORS

where SIZE = Large and ELECTRICAL = Yes and STATE = VI.

In addition to providing a list of the desired subcontractors' names and addresses, a utilityapplication program could also be written which would print mailing labels for the selected firms.

Other portions of the general contracting firm might also wish to use this list. For example, the

accounting department might use this relation to record the addresses of subcontractors for

payment of invoices, thereby avoiding the necessity to maintain duplicate files. In this case, the

accounting code number associated with each subcontractor might be entered as an additional

attribute in the relation, and the accounting department could find addresses directly.

Example 14-4: Historical Bridge Work Relation

As another simple example of a data table, consider the relation shown in Table 14-0 which might

record historical experience with different types of bridges accumulated by a particular agency. The

actual instances or rows of data in Table 14-4 are hypothetical. The attributes of this relation are:

PROJECT NUMBER - a 6-digit code identifying the particular project.

TYPE OF BRIDGE - a text field describing the bridge type. (For retrieval purposes, a

numerical code might also be used to describe bridge type to avoid any differences interminology to describe similar bridges).

LOCATION - The location of the project.

CROSSING - What the bridge crosses over, eg. a river.

SITE CONDITIONS - A brief description of the site peculiarities.

ERECTION TIME - Time required to erect a bridge, in months.

SPAN - Span of the bridge in feet.

DATE - Year of bridge completion.

ACTUAL-ESTIMATED COSTS - Difference of actual from estimated costs.

These attributes could be used to answer a variety of questions concerning construction experience

useful during preliminary planning.

TABLE 14-4 Example of Bridge Work Relation

Project

Number

Type of

Bridge Location Crossing Site Conditions

Erection

Time

(Months)

Span

(ft.)

Estimated less

Actual Cost

169137

170145

197108

Steel Plate

Girder

Concrete

Arch

Steel Truss

Altoona

Pittsburgh

Allentown

Railroad

River

Highway

200' Valley

Limestone

250' High

Sandy Loam

135' Deep Pile

Foundation

5

7

8

240

278

256

-$50,000

-27,500

35,000

As an example, suppose that a bridge is to be built with a span of 250 feet, located in Pittsburgh

PA, and crossing a river with limestone sub-strata. In initial or preliminary planning, a designer might

query the database four separate times as follows:

SELECT from BRIDGEWORK where SPAN > 200 and SPAN < 300 and where

CROSSING = "river"

SELECT from BRIDGEWORK where SPAN > 200 and SPAN < 300 and where SITECONDITIONS = "Limestone"

SELECT from BRIDGEWORK where TYPE OF BRIDGE = "Steel Plate Girder" and

LOCATION = "PA"

SELECT from BRIDGEWORK where SPAN < 300 and SPAN > 200 and ESTIMATED

LESS ACTUAL COST < 100,000.

Each SELECT operation would yield the bridge examples in the database which corresponds to the

desired selection criteria. In practice, an input/output interpreter program should be available to

translate these inquiries to and from the DBM and an appropriate problem oriented language.

The four queries may represent subsequent thoughts of a designer faced with these problem

conditions. He or she may first ask, "What experience have we had with bridges of this span over

" "




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14.6 Other Conceptual Models of Databases

While the relational model offers a considerable amount of flexibility and preserves considerable efficiency, there

are several alternative models for organizing databases, including network and hierarchical models. The

hierarchical model is a tree structure in which information is organized as branches and nodes from a particular

base. [8] As an example, Figure 14-2 illustrates a hierarchical structure for rented equipment costs. In this case,

each piece of equipment belongs to a particular supplier and has a cost which might vary by the duration of use.

To find the cost of a particular piece of equipment from a particular supplier, a query would first find the supplier,

then the piece of equipment and then the relevant price.

The hierarchical model has the characteristic that each item has a single predecessor and a variable number of

subordinate data items. This structure is natural for many applications, such as the equipment cost information

described above. However, it might be necessary to construct similar hierarchies for each project to record the

equipment used or for each piece of equipment to record possible suppliers. Otherwise, generating these lists of

assignments from the database illustrated in Figure 14-2 would be difficult. For example, finding the least

expensive supplier of a crane might involve searching every supplier and every equipment node in the database to

find all crane prices.

Figure 14-2 Hierarchical Data Organization

The network model or database organization retains the organization of information on branches and nodes, but

does not require a tree of structure such as the one in Figure 14-2. [9] This gives greater flexibility but does not

necessarily provide ease of access to all data items. For example, Figure 14-3 shows a portion of a network

model database for a building. The structural member shown in the figure is related to four adjoining members,

data on the joints designed for each end, an assembly related to a room, and an aggregation for similar members

to record member specifications.




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Figure 14-3 Example of a Network Data Model

While the early, large databases were based on the hierarchical or network organizations, the relational model is

now preferred in many applications due to its flexibility and conceptual simplicity. Relational databases form the

kernel for large systems such as ORACLE or SAP. However, databases distributed among numerous servers

may have a network structure (as in Figure 14-3), with full relational databases contained at one or more nodes.

Similarly, "data warehouse" organizations may contain several different types of databases and information files.

For these data warehouses, more complicated search approaches are essential, such as automatic indexing of

multi-media files such as photographs.

More recently, some new forms of organized databases have appeared, spurred in part by work in artificial

intelligence. For example, Figure 14-4 illustrates a frame data structure used to represent a building design

element. This frame describes the location, type, cost, material, scheduled work time, etc. for a particular

concrete footing. A frame is a general purpose data representation scheme in which information is arranged inslots within a named frame. Slots may contain lists, values, text, procedural statements (such as calculation rules),

pointers or other entities. Frames can be inter-connected so that information may be inheritedbetween slots.

Figure 14-5 illustrates a set of inter-connected frames used to describe a building design and construction plan.

[10]Object orienteddata representation is similar in that very flexible local arrangements of data are permitted.

While these types of data storage organizations are active areas of research, commercial database systems based

on these organizations are not yet available.

Figure 14-4 Illustration of Data Stored in a Frame




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Figure 14-5 Illustration of a Frame Based Data Storage Hierarchy

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14.7 Centralized Database Management Systems

Whichever conceptual model or database management system is adopted, the use of a central database

management system has a number of advantages and some costs compared to the commonly employed special

purpose datafiles. A datafile consists of a set of records arranged and defined for a single application system.

Relational information between items in a record or between records is not explicitly described or available to

other application systems. For example, a file of project activity durations and scheduled times might be

assembled and manipulated by a project scheduling system. This datafile would not necessarily be available to

the accounting system or to corporate planners.

A centralized DBM has several advantages over such stand-alone systems: [11]

Reduced redundancy good planning can allow duplicate or similar data stored in different files for

different applications to be combined and stored only once.

Improved availability information may be made available to any application program through the use of

the DBM

Reduced inconsistency if the same data is stored in more than one place, then updating in one place and

not everywhere can lead to inconsistencies in the database.

Enforced data security authorization to use information can be centralized.

For the purpose of project management, the issue of improved availability is particularly important. Most

application programs create and own particular datafiles in the sense that information is difficult to obtain directly

for other applications. Common problems in attempting to transfer data between such special purpose files are

missing data items, unusable formats, and unknown formats.

As an example, suppose that the Purchasing Department keeps records of equipment rental costs on each

project underway. This data is arranged so that payment of invoices can be handled expeditiously and project

accounts are properly debited. The records are arranged by individual suppliers for this purpose. These records

might not be particularly useful for the purpose of preparing cost estimates since:

Some suppliers might not exist in the historical record.

Finding the lowest cost supplier for particular pieces of equipment would be exceedingly tedious since

every record would have to be read to find the desired piece of equipment and the cost.

No direct way of abstracting the equipment codes and prices might exist.

An alternative arrangement might be to separately record equipment rental costs in (1) the Purchasing

Department Records, (2) the Cost Estimating Division, and (3) the Company warehouse. While these multiple




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A manager need not conclude from this discussion that initiating a formal database will be a panacea. Life is

never so simple. Installing and maintaining databases is a costly and time consuming endeavor. A single database

is particularly vulnerable to equipment failure. Moreover, a central database system may be so expensive and

cumbersome that it becomes ineffective; we will discuss some possibilities for transferring information between

databases in a later section. But lack of good information and manual information management can also be

expensive.

One might also contrast the operation of a formal, computerized database with that of a manual filing system. For

the equipment supplier example cited above, an experienced purchasing clerk might be able to immediately find

the lowest cost supplier of a particular piece of equipment. Making this identification might well occur in spite of

the formal organization of the records by supplier organization. The experienced clerk will have his (or her) own

subjective, conceptual model of the available information. This subjective model can be remarkably powerful.

Unfortunately, the mass of information required, the continuing introduction of new employees, and the need for

consistency on large projects make such manual systems less effective and reliable.

Back to top

14.8 Databases and Applications Programs

The usefulness of a database organization is particularly evident in integrated design or management

environments. In these systems, numerous applications programs share a common store of information. Data is

drawn from the central database as needed by individual programs. Information requests are typically performed

by including pre-defined function calls to the database management system within an application program. Results

from one program are stored in the database and can be used by subsequent programs without specialized

translation routines. Additionally, a user interface usually exists by which a project manager can directly make

queries to the database. Figure 14-6 illustrates the role of an integrated database in this regard as the central data

store.

Figure 14-6 Illustration of an Integrated Applications System

An architectural system for design can provide an example of an integrated system. [12] First, a database can

serve the role of storing a library of information on standard architectural features and component properties.

These standard components can be called from the database library and introduced into a new design. The

database can also store the description of a new design, such as the number, type and location of individual

building components. The design itself can be composed using an interactive graphics program. This program

would have the capability to store a new or modified design in the database. A graphics program typically has the

capability to compose numerous, two or three dimensional views of a design, to introduce shading (to represent

shadows and provide greater realism to a perspective), and to allow editing (including moving, replicating, or

sizing individual components). Once a design is completed and its description stored in a database, numerous

analysis programs can be applied, such as:

structural analysis,

daylight contour programs to produce plots of available daylight in each room,

a heat loss computation program

area, volume and materials quantities calculations.

Production information can also be obtained from the integrated system, such as:

dimensioned plans, sections and elevations,

component specifications,

construction detail specifications,

electrical layout,

system isometric drawings,

bills of quantities and materials.

The advantage of an integrated system of this sort is that each program need only be designed to communicate




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program for joint design might be included in the design system described above. Similarly, a construction

planning and cost estimating system might also be added.

The use of integrated systems with open access to a database is not common for construction activities at the

current time. Typically, commercial systems have a closed architecture with simple datafiles or a "captive,"

inaccessible database management system. However, the benefits of an open architecture with an accessible

database are considerable as new programs and requirements become available over time.

Example 14-5: An Integrated System Design

As an example, Figure 14-7 illustrates the computer aided engineering (CAE) system envisioned for

the knowledge and information-intensive construction industry of the future. [13] In this system,

comprehensive engineering and "business" databases support different functions throughout the life

time of a project. The construction phase itself includes overlapping design and constructionfunctions. During this construction phase, computer aided design (CAD) and computer aided

manufacturing (CAM) aids are available to the project manager. Databases recording the "as-built"

geometry and specifications of a facility as well as the subsequent history can be particularly useful

during the use and maintenance life cycle phase of the facility. As changes or repairs are needed,

plans for the facility can be accessed from the database.

Figure 14-7 Computer Aided Engineering in the Construction Industry

(Reprinted with permission from from Y. Ohaski and M. Mukimo, "Computer-Aided Engineering

in the Construction Industry,"Engineering with Computers, Vol. 1, no. 2, 1985.

Back to top

14.9 Information Transfer and Flow

The previous sections outlined the characteristics of a computerized database. In an overabundance of optimism

or enthusiasm, it might be tempting to conclude that all information pertaining to a project might be stored in a

single database. This has never been achieved and is both unlikely to occur and undesirable in itself. Among the

difficulties of such excessive centralization are:

Existence of multiple firms or agencies involved in any project. Each organization must retain its

own records of activities, whether or not other information is centralized. Geographic dispersion of work

even within the same firm can also be advantageous. With design offices around the globe, fast track

projects can have work underway by different offices 24 hours a day.

Advantages of distributed processing. Current computer technology suggests that using a number of

computers at the various points that work is performed is more cost effective than using a single,

centralized mainframe computer. Personal computers not only have cost and access advantages, they also




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Database diseconomies of scale. As any database gets larger, it becomes less and less efficient to find

desired information.

Incompatible user perspectives. Defining a single data organization involves trade-offs between

different groups of users and application systems. A good organization for one group may be poor for

another.

In addition to these problems, there will always be a set of untidy information which cannot be easily defined or

formalized to the extent necessary for storage in a database.

While a single database may be undesirable, it is also apparent that it is desirable to structure independent

application systems or databases so that measurement information need only be manually recorded once and

communication between the database might exist. Consider the following examples illustrating the desirability of

communication between independent application systems or databases. While some progress has occurred, the

level of integration and existing mechanisms for information flow in project management is fairly primitive. By andlarge, information flow relies primarily on talking, written texts of reports and specifications and drawings.

Example 14-6: Time Cards

Time card information of labor is used to determine the amount which employees are to be paid and

to provide records of work performed by activity. In many firms, the system of payroll accounts

and the database of project management accounts (i.e., expenditure by activity) are maintained

independently. As a result, the information available from time cards is often recorded twice in

mutually incompatible formats. This repetition increases costs and the possibility of transcription

errors. The use of a preprocessor system to check for errors and inconsistencies and to format the

information from each card for the various systems involved is likely to be a significant improvement

(Figure 14-8). Alternatively, a communications facility between two databases of payroll and

project management accounts might be developed.

Figure 14-8 Application of an Input Pre-processor

Example 14-7: Final Cos t Estimation, Scheduling and Monitoring

Many firms maintain essentially independent systems for final cost estimation and project activity

scheduling and monitoring. As a result, the detailed breakdown of the project into specific job

related activities must be completely re-done for scheduling and monitoring. By providing a means

ofrolling-overor transferring the final cost estimate, some of this expensive and time-consuming

planning effort could be avoided.

Example 14-8: Design Representation

In many areas of engineering design, the use of computer analysis tools applied to facility modelshas become prevalent and remarkably effective. However, these computer-based facility models

are often separately developed or encoded by each firm involved in the design process. Thus, the

architect, structural engineer, mechanical engineer, steel fabricator, construction manager and others

might all have separate computer-based representations of a facility. Communication by means of

reproduced facility plans and prose specifications is traditional among these groups. While transfer

of this information in a form suitable for direct computer processing is difficult, it offers obvious

advantages in avoiding repetition of work, delays and transcription errors. A de facto standard for

transfer of geometric information emerged with the dominance of the AUTOCAD design system in

the A/E/C industry. Information transfer was accomplished by copying AUTOCAD files from user

to user, including uses on construction sites to visualize the design. More flexible and extensive

standards for design information transfer also exist, such as the Industry Foundation Classes (IFC)

standard developed by the International Alliance for Interoperability (See http://www.iai-




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Back to top

14.10 References

1. Au, T., C. Hendrickson and A. Pasquale, "Introduction of a Relational Database Within a Cost Estimating

System," Transportation Research Record1050, pp. 57-62, 1986.

2. Bosserman, B.E. and M.E. Ford, "Development of Computerized Specifications,"ASCE Journal of

Construction Engineering and Management, Vol. 110, No. CO3, 1984, pp. 375-384.

3. Date, C.J.,An Introduction to Database Systems, 3rd Ed., Addison-Wesley, 1981.

4. Kim, W., "Relational Database Systems,"ACM Computing Surveys, Vol. 11, No. 3, 1979, pp. 185-

211.

5. Mitchell, William J., Computer Aided Architectural Design, Van Nostrand Reinhold Co., New York,

1977.6. Vieceli, A.M., "Communication and Coding of Computerized Construction Project Information,"

Unpublished MS Thesis, Department of Civil Engineering, Carnegie Mellon University, Pittsburgh, PA,

1984.

7. Wilkinson, R.W., "Computerized Specifications on a Small Project,"ASCE Journal of Construction

Engineering and Management, Vol. 110, No. CO3, 1984, PP. 337-345.

8. Latimer, Dewitt and Chris Hendrickson, Digital Archival of Construction Project Information,

Proceedings of the International Symposium on Automation and Robotics for Construction, 2002."

Back to top

14.11 Problems

1. Suppose we wish to develop a database consisting of contractor names, addresses and particular

specialties as in Table 14-3.

Suggest two hierarchicalorganizations of this data.

Suggest an alternative relationalorganization for this data.Which organization would you recommend for implementation of a database?

2. Suggest four reports which could be obtained from the warehouse inventory system described in Section

14.3 and describe what each report might be used for and by whom.

3. Suppose that a general contractor wished to keep a historical database of the results of bid competitions.

Suggest (a) the information that might be stored, and (b) a possible organization of this information.

4. For your suggested database from Problem 3, implement a prototype system on a spreadsheet software

program.

5. Describe a relational database that would be useful in storing the beginning, ending and all intermediate

stages for blockworld robot movements as described in Problem 6 in Chapter 9.

6. Describe a relational database that would be appropriate for maintaining activity scheduling information

during project monitoring. Be explicit about what relations would be defined, the attributes in each relation,

and allowable ranges of values.

Back to top

14.12 Footnotes1. See D.F. Rogge, "Delay Reporting Within Cost Accounting System,"ASCE Journal of Construction

Engineering and Management, Vol. 110, No. 2, 1984, pp. 289-292. Back

2. The system is based loosely upon a successful construction yard management system originally for Mellon-

Stuart Company, Pittsburgh, PA. in 1983. The authors are indebted to A. Pasquale for providing the information

and operating experience of the system. Back

3. Attributed to R. Lemons in J. Bentley "Programming Pearls," Communications of the ACM, Vol. 28, No. 9,

1985, pp. 896-899. Back

4. See Wilkinson, R.W. "Computerized Specifications on a Small Project,"ASCE Journal of Construction

Engineering and Management, Vol. 110, No. CO3, 1984, pp. 337-345. Back

5. See C.J. Date,An Introduction to Database Systems, 3rd ed., Addison-Wesley Publishing Company,

Reading, MA, 1981. Back

6. This is one example of a normalization in relational databases. For more formal discussions of the

normalizations of relational databases and the explicit algebra which can be used on such relations, see Date op

cit. Back

7. For a discussion of relational algebra, see E.F. Codd, "Relational Completeness of Data Base Sublanguages,"

Courant Computer Science Symposia Series, Vol. 6, Prentice-Hall, l972. Back

8. See D.C. Trichritzis and F.H. Lochovsky, "Hierarchical Data-Base Management,"ACM Computing Surveys

Vol. 8, No. 1, 1976, pp. 105-123. Back

9. For a more extensive comparison, see A.S. Michaels, B. Mittman, and C.R. Carlson, "A Comparison of

Relational and CODASYL Approaches to Data-Base Management,"ACM Computing Surveys, Vol. 8, No.

1 1976 . 125-157. Back




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Design and Construction,"Proc. of the Fifth ASCE Conference on Computing in Civil Engineering, 1987

Back

11. For a discussion, see D.R. Rehak and L.A. Lopez, Computer Aided Engineering Problems and

Prospects, Civil Engr. Systems Lab., Univ. of Illinois, Urbana, IL, 1981. Back

12. See W.J. Mitchell, Computer-Aided Architectural Design, Van Nostrand Reinhold Co., New York,

1977. Back

13. This figure was adapted from Y. Ohsaki and M. Mikumo, "Computer-aided Engineering in the Construction

Industry,"Engineering with Computers, vol. 1, no. 2, 1985, pp. 87-102. Back

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