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Property Addressing Plays Key Role in Locating Emergencies

Citizens of Henderson County expect that when they dial 9-1-1, emergency response personnel will be dispatched quickly to their location. This expectation is met because of the constant work of County personnel across numerous departments and divisions. The County Property Addressing Division plays a significant role in improving emergency service responses by constantly working to improve the accuracy of street and addressing data.

When a person calls 911, they are connected with an emergency telecommunicator in the 911 Center whose job it is to acquire critical information from the caller. At the same time, the E-911 computer system is using Automated Location Identification to connect the land line phone number (one of 62,273 in Henderson County) to an address (one of 59,570 in Henderson County). In February 2003, over half of the County’s phone numbers were not matched to property address points. In the years since, Property Addressing has worked to achieve a 99.28% accuracy in phone-line address point location. Because of these efforts E-911 knows exactly where the call comes from and sees that location instantly displayed on a computer generated map.

At the same time, the computer system analyzes associated street data, also maintained by the Property Addressing Department. There are more than 5,400 named streets within Henderson County. Street data contains valuable information for purposes of dispatching emergency calls for help. Each street is divided into segments within the county records and each segment contains specific data that includes:

During a 911 call, the computer system:

  1. identifies the caller’s general location along the street (based on the address number),

  2. identifies which side of the street the property is located,

  3. identifies which emergency service provider should be dispatched, and

  4. provides a route to reach the address.

The emergency telecommunicator in the 911 Center, with this information, is able to dispatch the correct fire department, ambulance or law enforcement officer to the caller.

Property Addressing works to ensure these data come together accurately. To this end, Property Addressing staff this fall achieved an accuracy rating of 99.95% in the street segment data (up from 71.87% in 2008) and 99.98% in address point data (up from 80.14% in 2008). With each data analysis Property Addressing further refines the data and corrects issues that arise. The data constantly change as new homes and businesses are built or when phone service is changed. Strict data control procedures allow Property Addressing staff to identify data errors. Often corrections are minimal, such as a street name misspelling, and can be corrected immediately.

Because of the continued effort of the Property Addressing Division, a caller who is unable to speak or provide any information to an E-911 telecommunicator can be located immediately with almost 100% accuracy. Henderson County serves as an example of best practices for Property Addressing data in the United States. The data standards and results in Henderson County have been used in presentations by groups at national conferences and training events.

The Property Addressing Division performs administrative planning and support for the enhanced 911 emergency telephone number, which has become a national standard. Personnel are able to pinpoint exact locations with the distance-based addressing system assigning unique street addresses to all structures in Henderson County. In the event of an emergency, pertinent information will display immediately and automatically to a dispatcher, greatly improving response time.Property Addressing issues property addresses, locates points to clarify Geographic Information System data, and coordinates individual addresses to match GIS, USPS, and AT&T data.