E911 Mapping

By John Fisher

The National Emergency Number Association (NENA) recently held a conference in Toronto. The conference underscored the serious issues facing the E911 system, and the impact that mapping and spatial data has on system effectiveness.

Despite decades of E911 history, implementation is still very spotty and inconsistent across jurisdictions. Multiple location referencing systems are in use, and there is far too little coordination across jurisdictions. Mapping and related spatial data to support E911 is very advanced in some areas but generally inconsistent and inadequate to the task. With some notable exceptions, government has not met the challenge of creating and maintaining the spatial databases necessary for E911 operations. An interesting observation arising out of the NENA conference was that in many cases there were private sector spatial databases that were far better than the government ones, but they were not being utilized. This suggests an opportunity to enhance E911 effectiveness through increased cooperation and coordination between the public and private sectors.

The rapid growth of cellular phones has both aided and exacerbated the E911 problem. Since far more people are now carrying cell phones, a much larger percentage of E911 calls are coming from mobile callers (for example, currently in the U.S.there are over 100,000 E911 calls per day originating from mobile phones).This has no doubt shortened the notification time significantly, but it means that the E911 dispatch cannot rely on the Automatic Location Identification (ALI) system to provide an accurate indicator of the caller's location. This has been well recognized as a liability and has led to FCC regulations and the current push to develop and deploy effective and cost-efficient methods of determining the location of mobile devices. All of this is well-covered ground. The issue of relevance here is the data side of this equation. Determining the caller's coordinates is only the first step. Other location issues include:

  • What is the spatial context? What street is that? What is the closest major intersection? What specific address is closest? What landmarks are nearby?
  • How do you get there? What is the best route for the emergency responders to follow?
  • Which Public Safety Answering Point (PSAP) boundary is that location within?
  • Where are the most appropriate response teams currently located?
  • If specialized response equipment required (e.g.jaws-of-life extraction tools; earth moving equipment; spill containment), where is the closest supply located?
  • Where should the victims be taken? The choice of hospital is dictated by a combination of specific care requirements (e.g.shock trauma; head injuries; internal bleeding) and their relative location to the accident scene.
  • Should air ambulance be called in? This will be in part dictated by access and egress issues. Where can the helicopter land?
There are also many ancillary spatial data issues that arise out of emergency situations. These include such things as where and how to reroute traffic, evacuate people, protect property, track and apprehend perpetrators. All of these requirements point to the need for accurate, timely, current and integrated spatial data that can be made immediately available to the various emergency responders. One of the lessons of 9/11 was the importance of good spatial data in emergency management.

Rural accidents pose a particular problem. Although only a relatively small percentage of accidents happen in rural areas, these accidents account for a disproportionate percentage of fatal accidents and long-term morbidity. This is predominantly the result of the increased length of time before rural accident victims receive proper medical care. In fact, there is a "Golden Hour" following an accident (first noted by shock trauma pioneer R.Adams Crowley). Severely injured patients who receive specialized trauma care during this crucial hour experience far less mortality and morbidity. Rural accidents have several characteristics that contribute to high latency times for patients reaching definitive care. These include:

  • Notification - it is far more likely that the accident will go unobserved and unreported, due to lower traffic volumes in rural areas, and the difficulty of contacting 911. This is improving with increased cellular coverage in rural areas.
  • Location identification - whereas in urban areas it is usually easy to identify where you are (street signs, house numbers, intersections, landmarks), such cues are sparse in rural settings. GPS, AGPS, GPRS, cellular triangulation and other methods of locating the accident scene are helping, but these improvements will take some time to implement.
  • Location context - knowing the coordinates of the accident location is helpful, but without additional contextual data the dispatcher does not know on which road the accident is on; what PSAP (Public Safety Access Point) boundary it falls within (and therefore which emergency services providers to dispatch to the scene; which hospital to notify; whether that hospital is equipped and currently staffed to handle trauma victims; and whether or not to scramble specialized services such as Air Ambulance or extraction equipment. This requires reverse geocoding, which takes the coordinates and relates them into identifiable map features.
For accidents that occur off-road, the problems are magnified. Many emergency mapping systems contain little or no detail of non-road features. Lakes, rivers, elevation, difficult terrain, trails, resource roads, clearings, landmarks and other mapping features that can be crucial in the management of an off-road emergency are frequently partially or completely missing from the databases being used for E911.

Even for emergencies in urban areas, E911 operations would benefit from improved spatial information such as: detailed land use polygons; power lines; gas lines; location of hazardous materials; day time/night time populations; and real-time traffic data. Much of this data already exists, in either the private or the public sector. By working effectively together we can save lives.


Published Wednesday, November 12th, 2003

Written by John Fisher



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