Los Angeles County
Automated GIS Election Mapping System
submitted to
1997 Esri User Conference
by
Somitra Saxena, Senior Analyst
GIS/Trans, Ltd.
2081 Business Center Drive, Suite 145
Irvine, CA 92612
e-mail: ssaxena@ca.gistrans.com
Vern Cowles, Division Manager
Election Systems and Precincting Division
County of Los Angeles
12400 Imperial Highway, 6th Floor
Norwalk, CA 90650
&
William Montgomery, Senior Analyst
Urban Research Division
County of Los Angeles
550 S. Vermont Avenue, Room 408
Los Angeles, CA 90020
e-mail:
wmontgom@co.la.ca.us
Abstract
The County of Los Angeles, with a population of over 8.9 million, comprises an area of 4,083 square miles and has approximately 3,800,000 registered voters. The County also has approximately 6,300 established precincts and 11,000 sub-precincts. The average voting precincts and polling places for its major election is 5,600 and approximately 29,000 precinct officers. The Registrar-Recorder/County-Clerk is responsible for maintaining the 600 districts of 50 different types, including 17 U S Congressional Districts, 14 State Senate, 25 State Assembly Districts, 5 Supervisorial, 88 incorporated cities and about 100 school districts. Realizing that GIS was the best suited technology to maintain this information, the County is shifting its future processing to a GIS environment.
The paper will discuss the development of the Map Creation System Interface (MCSI), an application to automate the conversion/production of the 1586 precinct maps. The map elements include street centerline, precinct and district boundaries with special symbology and annotation, customized legend enumerating major districts and other features. A user friendly interface was developed using ArcTools and AML, so that non-technical staff can create maps automatically without GIS training. Innovative use of Dynamic Segmentation for text, marker and route shield placement is included in the MCSI. The paper will describe the MCSI development and functionality.
1.1 The Challenge
The County of Los Angeles, Department of Registrar-Recorder/County Clerk (RR/CC), Precincting Section of the Registrar of Voters is required by law to provide maps of the election precincts to the public, candidates, political parties and file a set of maps for every major election with the California Secretary of State, as well as, keep a set for historical purposes. Among other responsibilities for conducting the general elections, it is also responsible for maintaining up-to-date information on the election precincts, various polling districts (e.g., Congressional Districts, Assembly Districts, School Districts, City Council Districts, etc.) and specialty districts (e.g., School Districts and Community College Districts with their trustee areas) for the whole of Los Angeles County.
Precincting Section had an IBM RISC 6000 running Esri's ArcInfo software and the Thomas Brothers Map Company's street database. The precinct maps were being done by the Department of Public Works (DPW), Automated Graphics Section using CADDS 4X for the cost of one engineer each year except when major reapportionments required massive district, boundary and annotation changes, then the cost went up. The County's Geographic Information Systems Advisory Body (GISAB) had established the Thomas Brothers Maps (TBM) file as the standard for use throughout the county and the Chief Administrative Officer's (CAO) Urban Research section had made the file available for use. Precinct boundaries had been added to the TBM base.
The challenge was to create an automated set of programs in GIS to produce an acceptable alternative to the 1,586 precinct maps currently provided by DPW. Precinct map samples were collected from other Registrar of Voters to help determine a cartographic style for the new maps. GIS/Trans, Ltd. was brought in to develop a GIS Election Mapping System to automate the process of creating, storing, updating and plotting the 1586 precinct maps for the county's 4,083 square miles area with 580 districts and almost 1,600 census tracts. The Map Creation System Interface (MCSI) was developed using AML, ArcTools and Dynamic Segmentation functionality in ArcInfo. Information Technology Services (ITS) provided contract administration and support functions. Urban Research provided technical and additional programming support.
1.2 GIS at RR/CC - Background
In 1977, a computer system was installed for the registering of voters. This system's design resembled an upside down pyramid with basic tables for editing being the tip and street segments and precincts with district information being the cap stone. On top of these were the voters and polls and officers data. At this time, precinct maps were hand drawn by the County Engineer (later to become part of DPW).
As the 1980 census approached, a computer card oriented system was designed and sub-precincts were established to recognize census tract lines. This was done because most reapportionment descriptions are done in whole and split census tracts. A system which was oriented toward census tracts would expedite processing the reapportionments.
About 1978 the County Engineer started using a Computer Aided Drafting and Design (CADD) system to do maps. With the new RR/CC computer systems, it seemed that we should join the modern world and have our precinct maps digitized. A test was run, a cartographic display approved and CADD was deemed acceptable. So, the RR/CC commissioned the digital maps to be created. This project took over three years from 1980 to 1983, because of continued changes. Two major district reapportionments were passed and processed in 1981 and 1983. The line and annotation changes required reprocessing the CADD work. So, the digitization effort seemed longer than it really took because of the additional changes imposed on the project.
The CADD precinct maps were actually quite nice. They had double lined streets so you could see district lines on the curb line or in the center of the street, as described. They were done on a one to four hundred foot scale (1:400) in 7,500 by 10,000 feet rectangles. Completed precinct maps are microfilmed. Rolls of film are used for historical purposes by the county and the state. Individual frames are cut and mounted in aperture cards which are indexed and used to make copies for the public.
In 1985, the Department participated in the first County meeting on Geographic Information Systems (GIS). We participated in a GIS Steering Committee and later in a user survey to determine the County's GIS needs. Later, when GISAB was formed, the RR/CC Department Head was named as it's first chair.
In 1987, the RR/CC started to replace the computerized voter system that had come up a decade earlier. The same basic design was being used, but the system was programmed in Natural using ADABAS and online transactions. This new system added a function called Future View to the geographic subsystem. Future View provided online transactions against census tracts to input new district data for major district reapportionments. It could also be used to process city, school, and other district reapportionments without having to be county wide. This online system became operational in 1989.
Also in preparation for the 1990 census, the Department decided that it should get more involved in precinct map generation. At first a CADD station compatible with DPW data was going to be purchased. This was reevaluated and a GIS RISC system was specified. The bids were evaluated and Esri's ArcInfo running on an IBS RISC 6000 was obtained in 1990.
The first effort was to try to interface with the DPS CADD data. A conversion program converted the CADD data in to ArcInfo compatible data. The normal problems with CADD data surfaced - lines that do not intersect, over shoot, and other such problems. Programmatically trying to close polygons did not work. It became obvious that a street line base map was needed. Fortunately, GISAB reached the same conclusion and issued a Request For Proposals (RFP) to obtain such a base map. As a result, the ETAK street file was purchased in 1993.
As a second effort, Precincting switched to the ETAK base file. ArcInfo programs in AML were written to add precinct lines to the ETAK file to create the precinct polygons. This process was completed in late 1994. Discussions were being held to determine if precinct map production could be accomplished on a file without the street annotation. It appeared that the process of adding street name text would take at least two years.
Then Mother Nature left a calling card - the January 1995 Northridge earthquake. During the emergency operations for the earthquake, the limitations of the ETAK file became obvious, and the Emergency Operations Bureau started using the TBM file. This was later explained to GISAB, and they changed their choice of a county street map base to TBM. The CAO as head of emergency operations for the County purchased the TBM and sub-leased it to other departments. So, in 1995, Precincting Section started digitizing precinct lines on the TBM base. This third start, while frustrating due to lost work, held hope, because the base file seemed finally to be a good one, with street annotations we could use.
The ArcInfo programs developed to enter the precinct lines on the ETAK base were easily modified to work on the TBM. Staff were experienced in using the ArcInfo programs so the work went fast. The TBM came with the annotation and other features shown in the Thomas Brothers Map Books. Having annotation and these features available made the idea of producing good quality precinct maps a viable proposition. The question was how to get an automated set of programs to produce the 1586 precinct maps. GIS/Trans, Ltd. was brought in to assist with the creation of Map Creation System Interface (MCSI).
2. Map Creation System Interface
The MCSI has been designed to bring in all the spatial and tabular data, and create precinct maps, similar to the original CADD based precinct maps, with minimal manual intervention. The interface was created using the Arc Macro Language (AML), ArcTools and Dynamic Segmentation functionality in ArcInfo. It is a collection of AML menus and programs (called AMLs) that allow the user, with minimal ArcInfo - GIS knowledge, to easily create, edit, view and plot precinct maps. It consists of several modules each specializing in a specific task. The 'Select Map Area' module lets the user select the precinct map to be generated. The general flow of the system to create precinct maps is illustrated in Figure 1. After selecting the map area, if required, the AnnoEdit module can be used to edit the annotation layer provided by Thomas Brothers. The edited annotation layer is saved for future map creation purposes. AutoMap module is utilized to automatically create a new map composition with minimal user intervention. EditMap is used to manually edit a selected map composition. The Output module provides the user with the capability to convert a map composition into a plot file and then send the file to the printer without having to exit the MCSI. This prompt menu allows experienced ArcInfo users to issue commands from a system or arc prompt without exiting the MCSI.
Figure 1. System Flow
Each menu choice either brings down a list of further choices or goes through and performs certain actions. Each main menu option, with it's corresponding actions or further choices, is described briefly in this paper.
This menu choice lets the user select the area to be mapped. The entire Los Angeles County data is divided into 109 tiles. Each tile contains up to 16 standard size precinct map areas. The map areas are numbered from 1001 through 2582. Clicking on Select Map Area brings up the following menu:
The user can select the map area by first selecting the tile, if the tile containing the map area is known, which will bring up a scrolling list of the 109 tiles or by directly selecting the desired map number from the scrolling list or the map. If a proper selection is not made, the application warns the user to start again.
The AnnoEdit modules allow the user to edit the Thomas Brothers annotation. Edited Annotation layer is saved for future map creation purposes. It starts an ARCEDIT session and brings up a display window with the AnnoEdit, Feature Selection and Edit menus (as shown below).
By default the module zooms to the selected map area and displays the annotation as the editing feature. Thomas Brothers street network and map area boundaries are shown in the background. This menu provides the tools to select one or many annotations, select user preferences, add/edit selected annotation features in the current edit coverage, save and exit the module. Experienced users are provided the opportunity to enter ARCEDIT commands at the command line.
Create & Edit Map takes the user into the map creation, display and editing modules. It starts an ARCPLOT session and brings up a display window with the AutoMap menu and the Display & Edit Menu (as shown below).
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The AutoMap module automates the map creation process by requiring minimal user interaction. It starts the execution of a series of about 50 AMLs by the MCSI to automatically generate the desired map composition. For most of the maps this process takes approximately 20 to 25 minutes. The interface first checks for the availability of all the data and also checks if the desired map already exists in the designated map storage area. If the map already exists, the user has the option of either viewing the existing map composition, editing the existing map composition or creating a new map composition.
If the user decides to create a new map composition, MCSI starts executing the AMLs, adding elements to the new map composition, and performing the following tasks:
1. Identify neighboring map area numbers to be placed on the map.
2. Draw neatlines (borders)
4. Identify and add to the map legend a list of the following districts in the selected map area:
Major Districts:
Cities & Unincorporated Areas
School districts with their Trustee Areas
5. Add north arrow and scale bar to the map composition.
6. Add Thomas Brothers Transportation features (street centerlines and railroads using different symbology). To enhance the quality of the map composition Thomas Brothers Annotation is optimized before it is added to the map composition.
7. Add linear (creeks, streams and rivers) and polygon (lakes, reservoirs and major rivers) hydrology features to the map composition.
8. All point feature markers (elementary, middle and high schools) with name and street address are added to the map.
10. Draw precinct and sub-precinct boundaries with special symbology and labels.
11. Create routes along major district boundaries to place markers (
l symbol for boundaries separating major districts, t for the school and community college district boundaries and é for the trustee area boundaries). Event tables are automatically created for optimal location of markers and the markers are added to the map composition.
12. Create routes in bulk along the district boundaries for text placement (text indicating the district on either side of the boundary, such as CD-29, is placed at regular intervals). Event tables are created for optimal location of the text and the text is added to the map composition.
The user is continually informed about the task being currently performed by the MCSI through information displayed in pop-up windows..
The user is allowed to make edits to the map created by AutoMap before finalizing the map composition and sending it for printing. Edit Map module allows the user to manually edit the map composition by providing functionality to: select, delete, copy, move, rotate and scale element(s); and add text/marker elements. It brings up the following menu with the editing tools:
3.0 Creative Use of Dynamic Segmentation
The RR/CC has very strict guidelines for the placement of text and markers on the standard precinct maps. Some of the requirements include:
CD - Congressional District
SD - Senate District
AD - State Assembly District
SU - Supervisorial District
BE - Board of Equalization District
MC - Municipal Court District
CN - City Council District
CC - Community College District
US - Unified School District
HS - High School District
ES - Elementary School District
CT - Census Tract
It was determined that utilizing Dynamic Segmentation tools was the only way to meet the mapping requirements outlined by RR/CC. Several AML programs and menus were developed to enhance the Dynamic Segmentation tools provided in ArcInfo. The tools were designed to identify the various district types and numbers present in the map area, generate routes along the boundaries of each of these districts ("on the fly"), generate optimal point locations (point events) along these routes for placement of markers and text, and use these routes and events to optimally place features on the map composition (illustrated in the figure below).
Some of the key functions added for the generation of routes and events are:
Route Maker:
Purpose: Creates routes on the boundary coverage, which are used to locate route event for placing text and markers.
Usage: mp_ind_routemaker <dist_type> <dist_name> {div_name}
<dist_type> The district type abbreviation (e.g. CD Congressional District, SD - Senate District etc.)
<dist_name> The district number or name. (e.g. 31 for Congressional District-31 or LS for Los Angeles Municipal Court)
{div_name} The division name if the district is further subdivided into divisions (e.g. 5 for City Council District 5). This is not a required input.
Optimal Event Locator:
Purpose: To determine the placement of markers and text along district boundaries. Placements are stored by location on a linear referencing system as Dynamic Segmentation point events, which are accessed by the MCSI software to draw text and markers. The events are placed by tracing along each route, placing shields at regular intervals, subject to the constraint parameters defined in the argument list.
Usage: mp_place_evt <coverage> <route_name> <first_interval>
<space_distance> <min_link> <min_int> <one_link>
<coverage> The name of the district boundary coverage with existing boundary routes.
<route_name> The name of the route for which events are to be located (CD31 refers to the route along Congressional District 31).
<first_interval> Optimal distance (in map units) from beginning of a route to place the first event. The macro will attempt to place the first shield on a route this distance along the route subject to the other constraints.
<space_distance> Optimal distance (in map units) between successive events placed on a route. The macro will attempt to place every event after the first this distance after the previous event, subject to the other constraints.
<min_link> Minimum length (in map units) of an arc allowable for placement of an event on that arc. The macro will not place any event on a link if the distance between the intersections is less than this distance.
<min_int> Minimum distance (in map units) to place an event from an intersection. The macro will not place a event any closer than this distance to an intersection and the length of the link is both less than twice this distance and greater than <min_link>.
<one_link> Optimal distance (in map units) between successive shields on one link. If placing a shield <space_distance> from the previous shield causes the two shields to be placed without an intersection between them, this distance will be used instead to distance the shield from the previous one.
4. Conclusions
The creation of the Automated GIS Election Mapping System at the Los Angeles County is regarded as a very successful application of the GIS technology. The project has achieved all it's established objectives and has provided the RR/CC several advantages over the old system:
