GIS IMPLEMENTATION AT THE CITY OF FALLS CHURCH, VIRGINIA

Successful implementation of GIS applications at the City of Falls Church within a relatively short period can be directly attributed to the commitment of City government to this new technology; effective management of the GIS implementation program by the City and its prime consultant; appropriate selection, support, and retention of qualified consultants throughout the needs analysis, systems selection, data acquisition, GIS database design- implementation and appliction development phases of the project; excellent coordination and cooperation among the various agencies involved; and the timely provision of needed information and support to the GIS application development effort.

INTRODUCTION

	The City of Falls Church, Virginia is situated a few miles southwest of 
Washington D.C., bordering Fairfax and Arlington Counties.  Although only two 
square miles in area, with 9,500 residents, Falls Church has a City Council 
organization and infrastructure similar to cities with much larger population.  The 
average household income in Falls Church is among the highest in the nation.  
The City currently provides water services for an area fifteen times larger than the 
City itself.  They share other services with the bordering counties, for example , 
911 despatch, fire, housing and human services, among others.

	In 1994, a commissioned study identified city-wide GIS needs for 
geographic data, hardware and software.  The study investigated existing 
computer systems and the City's individual departmental functional requirements, 
and recommended GIS hardware and software configurations, and data 
acquisition requirements for the City.  Following the recommendation, the City 
acquired initial GIS hardware and software, and contracted out acquisition of 
digital photogrammetric and  cadastral data.  Meanwhile, more than 20 personnel 
from different departments within the City were sent for Esri's GIS training.

	In 1995, the City contracted out for GIS database design and development 
services, and four key applications to demonstrate the practical implementation of 
the design.  The design incorporated elements of the Spatial Data Transfer 
Standard to facilitate data exchange between federal government, the neighboring 
counties, and the City.  Attributes for individual data layers were listed and key 
attributes for relational linkage identified.  A comprehensive data dictionary was 
compiled.  Many to many relationships among parcels, ownership, buildings, 
addresses, and tenancy were resolved.  Redundancies and data duplication were 
eliminated through a normalized relational design.

	The four applications selected were Zoning, Real Estate Value Analysis, 
Automated Homeowner Notification, and Historical Site Management.  In the 
zoning application, City zoning codes were defined within the zoning coverage 
and existing zoning patterns reproduced in ArcView.  A zoning map was created 
by overlaying the zoning and parcel coverages.  The real estate application was 
developed by establishing linkage between the the City's financial database on the 
IBM AS400 with the GIS.  Real Property Code (RPC)  number was the unique 
key utilized to set up linkage.  Residential and Commercial property values were 
thematically mapped.  Patterns of high and low property values were clearly 
distinguishable for different districts within the City.  Automation of property 
owner notification around a 150' annulus of a targetted parcel was achieved using  
the same RPC linkage and theme by theme queries in Arc View.  Homeowner 
names and addresses were accessed, a mailing list generated, and a wordprocessor 
used to merge each notification with the related  mailing label.  The Historic Site 
Management system was developed to create a site map, to help manage the City's 
inventory of historical sites.

	This paper describes the City's GIS hardware and software configurations, 
discusses database design issues, and provides technical details of the key 
application development process. GIS implementation experience gained during 
the first phase of development, and strategy for future development is discussed in 
the conclusion.
 
GIS CONFIGURATIONS

	Hardware, software, data acquisition, staffing and managment structure are 
components of the City's GIS configuration being discussed.

Hardware

	The IBM AS/400 system is the mainstay of the computer system currently 
being utilized for information services at the City's Finance Department. The Real 
Estate Database resident on the system is shared by most of the other departments 
within the City.  Others databases maintained on the AS/400 include water billing, 
traffic sign inventories, fire hydrant data, crime records, etc.  For GIS purposes, 
three IBM RS/6000 AIX workstations were acquired. They are separately located 
at the departments of Finance (the server), Public Works and Utilities, linked 
through a local area network. Other departments can access the RS/6000s through 
their personal computers over the same network.  Linkage of the primary GIS data 
to Real Estate Data downloaded from the AS/400 has been established on the 
RS/6000.  An HP650C ink-jet plotter and a 36"x48" Altek digitizer are also 
connected to each of the RS/6000s.  

Software

	ArcInfo and ArcView were the software platforms selected for the City's 
GIS. An Oracle relational database was designed for full-scale implementation.  
However, Oracle has not yet been installed, and Info tables are currently being 
used relationally for all application development.  Other software on the network 
include AutoCad, DBase V and a specialized Real Estate Appraisal package, 
among others.

Data Acquisition

	The GIS base data at the City was acquired through photogrammetry at a 
map scale of 1"=100' and 2-foot contours for generation of topographic maps. The 
photogrammetric base layers include:

	Topography 	Utilities		Transportation	Recreation
	Buildings	Traffic signs		Woodlands		Hydrology
	Parking	SurveyControl	Grid Systems
     
	Cadastral data was converted from the existing 1"=100' City parcel maps. 
The related layers are:

	Parcel/Lots 	Addresses	Easements	Zoning	Jurisdictions
     
	The GIS data was originally delivered in 23 tiles, corresponding to the 
existing map tiling system at the City. During the course of GIS implementation, 
it was decided that the initial photogrammetric and cadastral data would be easier 
to maintain in a single composite format due the relatively small size of the City, 
and the irregular shape of its jurisdiction. The composite was made by joining all 
individual tiles together for each of the coverages involved.

Staffing and Management

	The City's GIS is currently being managed by the Finance Department. 
The Director of Finance coordinates all GIS activities with other City agencies, 
citywide users, and outside jurisdictions, like neighboring counties and federal 
sources of information. Specific staff within the department have not been 
assigned solely, on a full-time basis, for GIS implementation during the first 
phase. Most of the work has been conducted on-site by an outside consulting 
team, with City departmental staff providing assistance on a project basis.  On 
completion of each application project, the processes are maintained by the 
departmental staff involved.




DATABASE DESIGN

	The database design process was divided into two components: logical and 
physical design.  Data layers and work flow among City agencies were mapped as 
part of the logical design.  The physical design implemented these logical 
relationships on the ArcInfo GIS platform.

Logical design

	Two important factors were critical to the logical design.  The first was 
compliance with the Spatial Data Transfer Standard (SDTS) in order to ensure 
shareability of data resources both internally within the City, and globally with 
other local governments, regional government, federal agencies, the private sector, 
etc.  The other was the aspect of data functionality for the variety of user 
departments, which has resulted in an application-driven orientation to design that 
ensures that the GIS will support future applications.  During the logical design 
phase, all GIS data was categorized into nine groups: 

1) Control and Grid Systems, 	2) Planimetric, 	3) Cadastral, 
4) Administrative,  			5) Facilities, 		6) Planning,             
7) Environmental,  			8) Routing, and 	9) SDTS Metadata.

	The functions for each department were identified and GIS information 
requirements discussed and listed.  Data category and sources were classified, and 
their associated attributes specified.  Potential applications for each department 
were determined.  As a result, over fifty applications were identified for user 
departments.  Flow of data between various City agencies was mapped to ensure 
efficient implementation of data sharing principles. 

Physical Design 

	The Physical Database Design document was developed on the basis of 
the logical database design, and established the logical relationships specifically 
to meet the physical layout requirements of the ArcInfo system.  Attribute tables 
were linked to graphics, and to each other through key index elements.  Although 
originally specified and designed for implementation of the relational modelling 
principles of Oracle, the design was robust enough to be implemented within 
INFO, keeping all entity relationships intact.  Entities were specified for data 
dictionary definitions (based on SDTS - Level 3 principles), and attribution with 
key relationship indeces, domains, and data characteristics.  Data integration and 
sharing between GIS and non-GIS users was also accommodated through 
relational linkage of each entity to metadata tables.  All data features and tables 
specified for each data category in the logical design were listed.  This document 
provided a comprehensive framework for the subsequent physical implementation 
stage of the City's GIS. 

KEY APPLICATION DEVELOPMENT

	As described in the logical database design phase, over fifty applications 
were identified to meet the strategic GIS needs of the City.  Among them, four 
key applications were chosen to test the database design and data integrity, and to 
demonstrate GIS capability in supporting the day-to-day City management 
decision making process.  These four were: Zoning, Real Estate Value Analysis, 
Automated Home Owner Notification and Historcal Site Management.

Zoning

	The Zoning application was designed to use digital zoning data to create 
zoning maps to replace those that were currently being maintained manually.  To 
create these maps, a zoning attribute lookup table classifying different zone 
categories was created, and  each zoning polygon populated on the Zoning 
coverage. The data was thoroughly checked and edited, to ensure compatibility 
between map products generated by the two systems (automated and manual). 
Some zoning changes had been implemented after the zoning coverage was first 
automated, so the coverage was updated accordingly.  Color and shade patterns 
similar, as far as possible, to the original manual drafting specifications, were 
selected to represent each zoning category on the map.  For greater visual effect 
and analysis, the zoning coverage was overlaid on the parcel base coverages.  The 
final map was processed using ArcPress and is ready to be plotted in any time, 
utilizing a simple command routine.

Real Estate Value Analysis
     
	Parcel polygons were the principal source of spatial data for the real estate 
value analysis application.  The City maintains its Real Estate Database on the     
AS/400.  A unique field named Real Property Code (RPC#) is utilized as the 
primary element to link all parcel-related information within the City. To derive 
parcel value data, a linkage was established between the Real Estate Database and 
the GIS parcel coverage.  The digital parcel base, however, contained numerous 
problems, partially because the source parcel maps didn't reflect the latest land 
ownership exchanges.  As a result, the data had to be thoroughly investigated and 
edited, before it could be used for real estate value analysis.

	In order to create a linkage between the spatial data coverage and the value 
attribute data, the parcel attribute table was populated with the RPC index 
numbers.  The manual effort to populate the approximately 4,000 RPC numbers 
was critical to establing the link between the GIS and all existing cadastral data 
currently being maintained at the City.  Assessment values for all properties could 
thus be automatically linked in this manner, and utilized to create thematic maps 
for value analysis.

	Real estate property is divided at the City into commercial, residential and 
non-classified categories for the purpose of separate analysis.  The first set of 
thematic maps created were for commercial and residential value analysis.  The 
parcels were first identified by category, and then classified for different value 
classes through a process of relational joining.  To represent different property 
value classes, colors were assigned to different value ranges, to enable rapid 
identification of concentrations of properties with low and/or high property 
values, clearly and distinctly displayed throughout the city separately for 
residential and commercial lands (see Figures 1 and 2).  These maps are being 
used by the City's real estate assessor to identify land assessment-related 
problems.



Automated Property Owner Notification

	The City is required to notify all property owners within a 150' annulus of 
a parcel before approval of construction or zoning changes can be permitted for 
that parcel.  Complete address information on land ownership was also available 
within the real estate database, and could be directly accessed through the linkage 
of established RPC index numbers.  Once relational joining was set up, all parcels 
within the 150' annulus of the targeted parcel were selected by a Theme By 
Theme Query.  Address information was downloaded from the real estate 
information to a DBase file, which is then utilized by a mail merge utility using 
word processing to generate the associated letters and mailing labels.  Many man-
hours are being saved, with improved efficiency and accuracy for this routine 
administrative task.

Historic Site Management

	This application was developed to manage the City's historical sites.  A 
map, generated from the GIS, was used to identify all buildings certified to be of 
historic significance.  Each historic site was identified on the system based on 
information furnished by the City Planning Department.  The building attribute 
table was linked to historical data, including certification dates.  A shape file 
distinguishing historic sites from other buildings within the City was created in 
Arcview.  Finally, a map displaying each historic building with distinguishing 
color characteristics compared to other buildings, was produced.  The map 
demonstrated the general distribution of historical sites within City limits.  Since 
RPC numbers could be linked to the historical buildings, other parcel-related 
information for those sites can now be retrieved and analyzed.
     
Conclusions

	Successful implementation of GIS at the City of Falls Church within a 
relatively short period of approximately one and a half years, can be directly 
attributed to the commitment of City government to this new technology, 
effective management of the GIS program, appropriate selection, support, and 
retention of qualified consultants throughout the needs analysis, system selection, 
data acquisition, database design and key application development phases of the 
project.  Coordination and cooperation among the various agencies involved, was 
also critical.  Key applications developed were not just for demonstration, but for 
real-time problem solving, and solutions derived focused on full implementation 
of a few applications on a City-wide basis.  The maps exhibited underlying trends, 
previously undetected patterns and distribution of resources.  The future 
development of the City's GIS program lies in integrating the GIS with other 
databases existing within the City and/or with other agencies, properly setting up 
data updating and maintenance procedures and methods, and direct involvement 
by individual user departments in continuous application development activity to 
support decision-making, and to improve efficiency, accuracy and productivity, of 
all related acivities in City management.
 





ACKNOWLEDGMENTS

	The authors would like to thank Mr. Shafiul Khan, Mr. Roman Arellano, 
and Ms. Fran Gioia of Engineering Systems, and Mr. Bill DeLanoy of the City of 
Falls Church for their support and assistance.

REFERENCES

	Engineering Systems, 1995. "Logical Database Design Specification", 
submitted to the Department of Financial Services, City of Falls Church.

	Engineering Systems, 1995.  "Physical Database Design Specification", 
submitted to the Department of Financial Services, City of Falls Church.

	He, Ping, Chapman, E., and Nag, S., 1995. "Quality Control in Full-Scale 
GIS Database Development for Local Government", in Proceedings of GIS/LIS 
'95, Volume 1, pp. 407-417.

	I-Net, Inc., 1994.  "Geographic Information System: Implementation 
Plan", Final Report, prepared for the City of Falls Church.

	Nag, Swapan, Singh, Y., Hogan, R., Scott, D., and He, P., 1995.  "Spatial 
Data Transfer Standards: a Practical Implementation in Local Government". 
Proceedings GIS/LIS '95, Volume 2, pp. 779-787.

	National Institute of Standards and Technology, 1992. FIPS Publication 
173: Spatial data Transfer Standards. U.S. Department of Commence.