Abstract
Accurate digital maps for Public Safety applications are paramount as E911 moves toward Phase II wireless requirements. Responding to wireless calls within 125 meters will require accurate, geo-referenced base maps. Public Safety organizations need to compile existing GIS data, GPS road centerline data, boundaries, imagery and addressing. CAD vendors utilize this GIS data for their tactical map to locate incidents and perform unit recommendations. These base maps are required as organizations add AVL to their CAD for improved dispatching and response. This presentation will discuss how the puzzle comes together and provide examples of areas already implementing this process.
CompassCom, Inc., based in Englewood, Colorado, is a solution provider for Automatic Vehicle Location (AVL) systems, Geographic Information System (GIS) mapping and Global Positioning System (GPS) applications. CompassCom has been providing custom mapping solutions to meet Phase II wireless requirements for two years. As public safety moves toward meeting the requirements for Phase II wireless, accurate, digital maps become a necessity. This paper will give a brief overview of the Phase II wireless requirements mandated by the FCC, discuss what the requirements mean and outline the process for creating a new, digital base map.
There are essentially three phases of Wireless E911. The first, Phase 0, states that wireless 911 calls must be transmitted to a PSAP (Public Safety Answering Point) whether the caller is a subscriber or non-subscriber of the wireless carrier. The second, Phase I, states that the wireless call must come to the PSAP with the wireless phone call back number. The third, Phase II, states that the wireless call must come to the PSAP with the wireless phone call back number AND location information.
The statistics for wireless callers in the past 10 years is astounding. Obviously, as the number of wireless telephone users has increased, so has the number of wireless calls. In fact, the number of 911 calls made by wireless telephone users has increased more than 10 times. Of the total number of 911 calls made today approximately 30% are made by wireless telephone users. A number that is expected to more than double in the next few years.
Location information for a wireless phone caller can be determined via two methods; handset-based technology and network-based technology. An example of handset-based is a wireless telephone with an imbedded GPS receiver to transmit the caller’s location information. The network-based method involves triangulation of cell cites. The accuracy standards and timeline, as set forth by the FCC, are as follows:
Handset-based solutions:
Accuracy
50 meters for 67% of calls
150 meters for 95% of calls
Timeline
Begin selling ALI-capable handsets by October 1, 2001
New ALI-capable handset activations
25% by December 31, 2001
50% by June 30, 2002
100% by December 31, 2002
Achieve 95% penetration of ALI-capable handsets by December 31, 2005
Network-based solutions:
Accuracy
100 meters for 67% of calls
300 meters for 95% of calls
Timeline
Within 6 months of PSAP request, wireless carrier must provide ALI for 50% of PSAP’s coverage area or population
Within 18 months of PSAP request, wireless carrier must provide ALI for 100% of PSAP’s coverage area or population
In addition to what the requirements stipulate, the big question is, “What about maps?” Public safety organizations must have accurate, digital maps capable of displaying latitude/longitude coordinates. Many current maps used in public safety applications are geocoded, but not geo-referenced. Geocoded means that each street segment on the map is associated with an address range and a street address can be easily located. However, geocoded data is not referenced to any particular position or area on the face of the earth. A latitude/longitude position would have no meaning on a geocoded map. Geo-referenced means each street segment is associated with a true position on the face of the earth. Latitude/longitude coordinates have meaning and can be located on a geo-referenced map. CAD (Computer Aided Dispatch) systems must also be able to accept new maps to meet the new requirements for wireless callers. It is vital that the maps be maintained and kept up-to-date, especially in high growth areas. The real meaning of Phase II wireless requirements is that accurate, geo-referenced, digital maps for public safety are no longer a luxury, but a necessity!
Digital maps are also important as public safety moves toward implementing AVL to achieve more efficient dispatching. In conjunction with an accurate base map, AVL and CAD can help improve dispatching and reduce response times by providing unit recommendations and routing closest vehicles via true and accurate street networks. Many systems currently dispatch based on an “as the crow flies” distance. This is a straight-line distance and can be deceiving for the dispatcher. A call that seems closer to a station by a straight line may actually be accessed quicker by another station according to the street network. It can make a significant different in response times.
CompassCom can assist your city, county or district in upgrading an existing base map or creating a new and accurate base map that is Phase II-compatible. The project approach for upgrading or creating a base map consists of five steps: reviewing and incorporating existing data, creating new data, addressing, quality assurance and control, and maintaining the data.
Step 1: Review and Incorporate Existing Data. This process includes determining what data is already available and if it meets the accuracy standards as set forth for the project.
Step 2: Create New Data. The new data created should fill in gaps where existing data is not available or the accuracy does not meet the project specifications. There are several different methods for collecting new data that meet the stated accuracy standards, including heads-up digitizing and DGPS.
Step 3: Addressing. Once all data, existing and new, is compiled, each line segment must be addressed. To achieve a high level of accuracy for addressing, the process requires participation and cooperation by a majority of the parties involved in the project. The addressed data, combined with other GIS data layers, is beneficial for dispatchers, public safety officials, GIS departments and others.
Step 4: Quality Assurance / Quality Control. As with collecting new data, there are several methods that can be implemented to perform the QA/QC task. One of the most important is the comparison of the new base map data with the MSAG (Master Street Address Guide).
Step 5: Maintenance. Quite possibly the most important step in the process. A base map can become “out-of-date” very quickly. The five-step process should be repeated at reasonable intervals to keep the project area base map as current as possible. For example, once the base map is created, update it every month or every quarter, depending on the level of growth in the area. Promoting data sharing among cities, counties and public safety agencies is a positive step toward keeping data current and improving public safety services. A well maintained, accurate base map saves lives.
The saying, “No data is better than bad data,” is very true when referring to base map data. The requirements mandated by the FCC for Phase II wireless created the need for accurate, geo-referenced maps for use in public safety applications. Let CompassCom HELP YOU upgrade or create a custom base map for your city, county or district, allowing you to easily and quickly HELP OTHERS.
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