A diagnostic expert system to improve the quality of Naval Facilities Engineering Command (NAVFAC) construction drawings and specification is described. C Language Integrated Production System (CLIPS) and computer aided design layering standards are used in an expert system to check and coordinate construction drawings and specifications to eliminate errors and omissions

Antelman, Albert

English

NASA Technical Reports Server

IMPROVING NAVFAC's TOTAL QUALITY MANAGEMENT
OF CONSTRUCTION DRAWINGS WITH CLIPS
by
Albert Antelman AIA
Shore Facilities Department
Naval Civil Engineering Laboratory
Port Hueneme, CA 93043
ABSTRACT This paper describes a diagnostic expert system to improve the quality of Naval
Facilities Engineering Command (NAVFAC) construction drawings and specification. CLEFS
and CAD layering standards are used in an expert system to check and coordinate construction
drawings and specifications to eliminate errors and omissions.
INTRODUCTION
Designing and constructing naval shore facilities for the United States Navy is a complex
process. The quality of construction documents is a major factor in this process. The review
and coordination of construction drawings and specifications is one of the critical tasks performed
by NAVFAC architects and engineers. Defective drawings and specifications can lead to change
orders, time delays, and litigation.
Experience has shown that more than half of the errors and omissions found in
construction drawings and specifications result from inadequate coordination between architec-
tural and engineering disciplines (Nigro, 1984). A recent study by the U.S. Army Corps of
Engineers found that more than 95 percent of all review comments addressed coordination issues
(Kirby, 1989).
In response to the problem, NAVFAC implemented a quality assurance program in
April of 1986. An interdisciplinary coordination review checklist was developed to check
for in-consistencies, interferences, errors and omissions, both technically and graphically, that
may exist in or between disciplines. A recent survey by Charles Markert, NAVFAC's Deputy
Assistant Commander for Engineering and Design found that NAVFAC has discovered signifi-
cant benefits from conducting interdisciplinary coordination checks at the final design stage of
projects (DCQI, 1990).
The NAVFAC interdisciplinary coordination checklist contains over 500 review items.
The checklist, when used conscientiously, can eliminate many of the design deficiencies which
have occurred in past construction projects. Current procedures calls for each checklist item to
be analyzed for applicability to the project's drawing and specification content. This is
accomplished by manually reviewing the drawings and specifications with the checklist. If
an item is found not applicable, the letters "NA" will be inserted adjacent to the checklist item.
The remaining checklist items are used to perform the interdisciplinary coordination rev lew.
357
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THE PROBLEM
The development and application of quality control coordination checklists is a step in the
right direction, but does not provide a production oriented solution to the problem. Often
checklists contain several hundred items which may not be applicable to the drawing and
specification content Typically, due to quantity and nonapplicability, checklist items are often
ignored during. the review process. The process of editing, comparing, and coordinating
checklist items with the drawings and specifications is time consuming considering it is not
unusual for project drawings to exceed 50 sheets. Checklist editing also assumes a level of
experience the reviewer may not possess and may well result in the non-prioritizing of the issues
being checked.
The majority of NAVFAC's construction drawings are produced using manual drawing
procedures, but this is rapidly changing. NAVFAC as well as architectural/engineering firms
under contract to NAVFAC have made heavy investments in computer-aided design (CAD)
hardware and software. Receiving construction drawings delivered in a CAD format is becoming
common. Despite the self-coordinating aspects of CAD drawings, coordination and omission
errors can still arise. No matter what process (manual drafting, systems drafting or CAD) is used
to produce a set of construction drawings, all drawings need to be checked (Duggar, 1984).
OBJECTIVE
The objective of this project is to produce an easy-to-use, automated, expert system, capable of
quickly analyzing project data (drawing and specification content), recognize potential
coordination issues, establish review priorities and provide quality control guidance specific
to the project being reviewed. The expert system must function as an intelligent assistant which
provides the user with knowledge (advice) based on expert experience and lessons learned
from past projects with similar drawing content.
SOLUTION
The solution to the problem of automating the quality review of construction drawings and
specifications is to develop a rule-based diagnostic expert system capable of reading the drawing
contents of CAD drawing database files. The C Language Integrated Production System
(CLIPS) was selected as the expert system shell and AutoCad software running in conjunction
with the CadPLUS Total Architectural/Engineering software was selected to produce the CAD
drawings.
The CAD Data Base
The CadPLUS Total Architectural/Engineering System is a powerful facility design tool
developed by the Naval Civil Engineering Laboratory and CadPLUS Products Company
of Albuquerque, NM under a Cooperative Research and Development Agreement. The
358
software runs in conjunction with AutoCad and implements the CAD Layering Guidelines
published by the American Institute of Architects (AIA).
In order to insure reusability of CAD drawings during a facility's life cycle, NAVFAC
has adopted a standard approach for the use of CAD layers. Layering is "the basic method most
CAD systems use to group information for display, editing, and plotting purposes" (Schley,
1990a). NAVFAC along with the American Institute of Architects, the American Consulting
Engineers Council, the American Society of Civil Engineers, International Facility Management
Association, United States Army Corp of Engineers and the Department of Veterans Affairs
sponsored the development of a standard approach for the use and naming of CAD layers.
It was not the intention of the CAD Layering Guidelines to attempt to use layers to carry
"drawing intelligence" (Schley, 1990a), however the CAD Layering Guideline's structure
and format, see Figures 1 through 5, provide a detailed description of a project's drawing
content. Drawing content is the key to determining the applicability of interdisciplinary
coordination checklist items.
rM»JOR CBQUP
A^cf* t*C t LM
Stfucturo!
discipline grouo*
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d«f f ermttotiOA Of mnor groups.
rU$ER Dense tt Optional fund to
[ acconnodat* fprcat project
r
x - x x x x - x x x x - x x x x
Figure 1. AIA layer name format (Schley, 1990b)
A-UQQft BOOtS
A-GLAt WWIOWS
A-n.m rLOOi wo
A-CQPM COUVWKI
'-OHO ctiLiNC pro
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Figure 2. Typical building and drawing layers without modifiers (Schley, 1990b).
359 ORIGINAL PAGE IS
OF P00« QUALITY
The layer modifiers listed below nay be used with
any building ifornation layers.
IDENTIFICATION TAG
CROSS -MATCHING AND PQCHE
VERTICAL SURFACES C3D DRAWINGS)
EXISTING TO REMAIN
EXISTING TO BE DQCLISHED OR REMOVED
NEW OR PROPOSED WORK (REKQDELtNG PROJECTS)
USED TO DESIGNATE WALLS TO REMAIN
•-••••-PATT
•-..«.-CL£V
• -••••-OST
.-....-DEMO
«-««««-NEW
EXAMPLE'
A-WALL-EXST
Figure 3. Building information layer (Schley, I990c).
The layer modifiers listed below nay be used with
any drawing ifornation layers.
• -•«»«-NOTE NOTES. CALL-OUTS AND K£Y NOTES
.-.•••-TEXT GENERAL NOTES AND SPECIFICATIONS
• -••••-SYMB SYMBOLS, BUBBLES. AND TARGETS
»-«.««-DIMS DIMENSIONS
«-«»««-PATT CROSS-HATCHING AND POCK
• -••••-TTLB TITLE BLOCK. SHEET NAME AND NUMBER
i-«««-NPLT NQNPLOT INrORHATIDN AND CONSTRUCTION LINES
•-•.•••-PLOT PLOTTING TARGETS AND WINDOWS
Figure 4. Drawing information layer modifiers (Schley, I990c).
Modifiers nay be added to layer names for further
differentiation, for exanpie. ceil.ng infornation (A-CLNG)
nay b* categorized as-
A-CLNG-GRID CEILING GBID
A-CLNG-OPCN CEILING AND ROOT PENETRATIONS
4-CLNG-TEES K«1N TEES
A-CLNO-SUSP SUSPENDED ELEMENTS
4-CLKG-PATT CEILING PATTERNS
Figure 5. Typical ceiling modifiers (Schley, 1990c).
360 ORIGINAL PAGE I
OF POOR QUALIT
CLIPS Expert System Shell
CLIPS is a forward chaining rule-based expert system shell, "designed at NASA/Johnson Space
Center with the specific purpose of providing high portability, low cost and easy integration with
external systems" (Giarratano 1989a). The three major components of the CLIPS expert system
shown in Figure 6 are:
1. Fact-list: global memory for data
2. Knowledge-base: contains all the rules
3. Inference engine: controls overall execution
"In order to solve a problem, the CLIPS program must have data or information with
wnichitcan reason. A chunk of information in CLIPS is called a fact" (Giarratano 1989b). The
programs fact-list is a product of the CAD drawing database. A LISP program within the CAD
system is used to generate an ASCII file (layer.dat) listing all layers present within the CAD
graphic database. The CLIPS load-facts function is used to input the facts into the program.
The following are examples of facts :
Fact List Description
(a-wall-new) Architectural wall, new
(a-prof) Roof Plan
(s-psfr) Structural Framing Plan
(p-strm-rfdr) Roof Drain
(e-prof) Electrical Roof Plan
A rule is the method that CLIPS uses to represent knowledge. An example of a possible rule for
checking drawing coordination is:
IF the project drawings contain a Roof Plan and Roof Framing Plan.
THEN coordinate the Roof Plan with the Roof Framing Plan and verify
direction of roof slope.
The rule expressed in CLIPS format would appear as:
(defrule coordinate-roof-plan-and-roof-framing-plan
(a-prof)
(s-psfr)
=>
 ;f.(fprintout t "Coordinate the Roof Plan with the Roof Framing
Plan" crlf)
(fprintout t "Verify direction of the roof slope."
crlf))
361
SPECIFICATIONS
CAD rn.cs
DRAWINGS
A/E 1001 SUBMISSION TO
N A V F A C P R O J E C T A R C H / E N G
MASTER CHECKLIST
GENERAL G|,Gj_.G.
ARCHITECTURAL
STRUCTURAL S,.S»_.S.
MECHANICAL M,X8_M ,
PLUMBING P, .PS._P.
HRE
ELECTRICAL E|£j...E.
CIVIL C,.Ce,.C.
LANDSCAPE LI.LJ...L.
F A C T L I S T
INPU T
R U L E S
O U T P U T
N A V F A C I N T E R D I S C I P L I N A R Y
C O O R D I N A T I O N C H E C K L I S T
A D V A N T A G E S :
• Automated drawing content
review.
Autonated checklist editing.
Increased productivity
[ngroved quality control
Built-in expertise
Review itens can be prior.tized.
Checklist itens can be easily
added or removed by users
P R O O U C T
PROJECT ASCH/ENG
CONDUCTS INTERDISCIPLINARY
COORDINATION RCVICV
A C T I O N
PROJECT ARCH/ENG
FORWARDS REVIEW
COMMENTS TO A/E
Figure 6. Prototype work model.
The knowledge-base rules are a product of the existing NAVFAC interdisciplinary
coordination checklist and REDICHECK. REDICHECK, which was developed by LCDR
William T. Nigro, CEC, USN (Ret) is a structured coordination review system that is also
implemented by using a manual checklist.
The CLIPS inference engine makes inferences by deciding if a rule is satisfied by the facts.
For example, if a project under review contained a Roof Plan (layer a-prof) and a Framing Plan
(layer s-psfr), then pattern matching would occur in the previously defined defrule and the
knowledge-base would consider the review comment as applicable. In this application, the CLIPS
knowledge-base consists of rules that when activated by matching facts, outputs a project-specific
quality control coordination checklist.
The rules required to generate a project-specific checklist are embedded in the CLIPS
program. In order to reduce the size of the program, the master checklist items are stored outside
the program and accessed by the CLIPS read function.
362
ORIGINAL PAGS
OF POOR QUAL
CLIPS also has a feature to control the execution of rules called salience. Salience values
are used to order the rules in terms of increasing priority and will activate rules to assemble a
prioritized project specific checklist
FUTURE WORK
To date, much progress has been made in understanding the problem domain and
developing the knowledge-base. Future development plans include:
1. Development of a menu driven interface.
2. Development of rules that identify omissions, duplications, and inconsistencies
between reference/identification symbols (detail bubbles, door reference symbols,
equipment numbers, etc.) and details, sections, and schedules.
3. Development of rules that identify omissions, duplication, and inconsistencies
between labels/keynotes and project specifications.
4. Development of an interface between the CAD geometric data base and the CLIPS
knowledge-base.
CONCLUSIONS
At a recent Naval Sea Systems Command conference, Admiral Frank B.Kelso, II, Chief of Naval
Operations commented that we have "to learn to do things more efficiently; with better quality
than we had in the past." In this application, CLIPS provides NAVFAC with a powerful tool
to improve the total quality management of the construction document review process.
ACKNOWLEDGMENTS
The author acknowledges the advice and assistance of Dr. Jens Pohl, CAD Research Unit.
School of Architecture and Environmental Design, California Polytechnic State University,
San Luis Obispo, California.
REFERENCES
DCQI, (1990). Design & Construction Quality Institute Newsletter, Spring 1990, Washington
D.C.,pgl.
Duggar III, J.F. (1984). Checking and Coordinating Architectural and Engineering Working
Drawings, McGraw-Hill Book Company, New York, pg. 4.
363
Giarratano, J. (1989a). Expert Systems, Principles and Programming, PWS-KENT Publishing
Company, Boston, pg. 373-374.
Giarratano,!. (1989b). Expert Systems, Principles and Programming, PWS-KENT Publishing
Company, Boston, pg. 379.
Kirby, J. G. (1989). Constructibility and Design Reviews: Analysis and Recommendations
for Improvement, US ACERL Technical Report P-89/15, US Army Corps of Engineers,
Construction Engineering Research Laboratory, pg. 25.
Nigro,W.T.LCDR(1984). REDICHECK: A System of Interdisciplinary Coordination, DPIC
Communique, Vol. 11, No. 6, Montery, pg. 3.
Schley, M. K. (ed)(1990a). CAD Layer Guidelines: Recommended Designations for Architec-
ture, Engineering, and Facility Management Computer-Aided Design, The American
Institute of Architects, Washington D.C., pg. 11.
Schley, M. K. (ed) (1990b). CAD Layer Guidelines: Recommended Designations for Architec-
ture, Engineering, and Facility Management Computer-Aided Design, The American
Institute of Architects, Washington D.C., pg. 13 and 16-20.
Schley, M. K. (ed)(1990c). CAD Layer Guidelines: Recommended Designations for Architec-
ture, Engineering, and Facility Management Computer-Aided Design, The American
Institute of Architects, Washington D.C., pg. 21 and 23.
364


Improving NAVFAC's total quality management of construction drawings with CLIPS

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