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MassGIS and NextGen 911

Learn how MassGIS is playing a crucial role in the state's Next Generation 911 Emergency Call System, and what this means for cities and towns.


MassGIS works very closely with the State 911 Department in the state’s Executive Office of Public Safety and Security on the Next Generation 911 (NG911) Emergency Call System. MassGIS’ role has been to develop, and now to maintain, the map and address information relied upon by NG911 to route emergency calls to the correct dispatch center. The State 911 Department completed deploying Next Generation 911 as of January 2018. The department is now working to realize the potential benefits that the new system has to offer.

The information below explains how the new system is different, what MassGIS is doing for the State 911 Department, how municipal address information is or can be integrated into this project, and identifies address assignment best practices. Because municipalities assign new addresses, they have a key role to play in, and should ultimately assume responsibility for, keeping their address information current in the new emergency call system.

The legacy Enhanced 911 (E-911) call system was established when all phones were landlines. When you called 911, your telephone carrier used your phone number to look up the corresponding physical address (“123 Jones Avenue”) for the phone number in a database. The database identified the appropriate public safety emergency call routing or dispatch center (PSAP or “public safety answer point”); the 911 system then used that information to route the 911 call to the correct PSAP. NG911 replaces this database lookup with a new approach that relies on computerized maps and related information to route calls. In NG911the physical location of the caller (could still be an address, but most likely the location is provided by a cell phone) determines which PSAP gets the call. Reasons for implementing NG911 include transitioning the 911 call routing system to be entirely computer-based which, in turn, accommodates other ways of contacting 911 (e.g., text messages), makes it possible for dispatch centers to be backed up by other centers, and provides the ability to interconnect with other Next Generation 911 systems.

Additional Resources

How Next Generation 911 is different

The Next Generation 911 or “NextGen 911” system depends on high quality mapping: maps of emergency service zone boundaries, maps of address locations as points, and maps of roads. In the NextGen system, location information determines where the call is answered: for cell calls, longitude/latitude provided by the phone or an approximate location based on which cell towers receive the call signal; for landline phones, the addresses.When combined with an Emergency Service Zones (ESZs) boundary map, call locations are used to route calls to the correct dispatch center. In the dispatch center, the call is displayed with a map to assist in verifying the location of callers; this map includes address locations as points. MassGIS mapped the emergency service zones in consultation with municipal public safety staff and has mapped, as a point, the location of every address in the Commonwealth.

Emergency Service Zones (ESZ) are the geographic areas for which a specific 911 call center dispatches ambulance, fire, and police services. These zones often do not match municipal boundaries although they often follow assessor parcel boundaries

How MassGIS is mapping address locations

You may be familiar with MassGIS’ standardize statewide assessor tax mapping for use in geographic information system (GIS) software. While standardized mapping has many well documented benefits, the principal reason for the standardization was because ESZ boundaries can only be mapped if you have a representation of property boundaries; mapping ESZs would have been impossible without standardized parcel mapping in GIS. In addition, assessor site addresses linked to parcels on the assessor maps were an important beginning for mapping address locations. This is because if you know the site address for a parcel, you likely know the address for the structure(s) on that parcel. The needs of the NextGen 911 project for parcels and site addresses drove completion of statewide standardized parcel mapping.

MassGIS is also using site plans and similar documents to determine the correct location for addresses in multi-building complexes such as condominium complexes, college campuses, and office parks (“sites”). MassGIS has also received information from some municipalities that has been incorporated into the MassGIS master address database for that community. Finally, since October 2015, MassGIS has had technicians in the field resolving address mapping issues, especially for multi-building complexities and for mixed use developments.

As of February 1, 2018, MassGIS has mapped 2,149,000 address locations and field technicians have edited 352,000 points. The master address database linked to these address locations contains 3,400,000 address records. All this work was done in accordance with standards established by the National Emergency Number Association (NENA).

Learn more about NextGen 911 and mapping

What MassGIS has developed for NextGen 911

For every city and town, MassGIS has developed a master address resource. This resource consists of 1) a master list of addresses, assembled from multiple sources, and 2) a map of points, derived from statewide mapping of buildings; the building points represent potential address locations. The guiding principles for this work are:

  • Each building point has an address
  • Each address is assigned to a location (usually a building point)

MassGIS’ master address resource for each community is as complete as we can make it from the available address sources (assessor site addresses, Comcast subscribers and Voter Registration Information System; these were validated for completeness using the Emergency Service List from Verizon). Further progress will depend on input from people working in the field or from those with local knowledge. Some of the challenges we face are: addresses that don’t match parcels (for example, apartment complexes, housing authority properties, mixed use buildings); structures without addresses; addresses with unknown location; and multi-building sites.

>> View all Master Address Database products available from MassGIS

I already have a master address list. Is MassGIS going to ignore that?

No. Some communities have already put significant effort into developing master address lists or even address point mapping in GIS. MassGIS wants to work with these communities to incorporate these existing data sets into the MassGIS project. Collaborating with communities in this way provides further validation of our addresses and address locations. Municipal collaboration will also help with identifying addresses we may have missed; we see this as a win-win situation.

What if I have a consultant working on my master address list?

MassGIS is also happy to work with third party providers that are assisting or can assist communities with developing master address resources. We encourage communities to have their consultants contact us concerning work on addresses. Similarly, if your community is planning to purchase a permitting system, if you do not already have a master address database that you know to be comprehensive, you should have your vendor work with one of the MassGIS master address download options for your community.

How does MassGIS learn about new addresses?

Find out how you can be sure new addresses are added to the NextGen 9-1-1 system.

I assign addresses. Are there best practices for address assignment?

The following basic rules should govern address assignment in all jurisdictions:

  1. The street name should be the name of the street from which the addressed location is accessed, either directly or via an un-named driveway or access road.
  2. If two or more distinct addressed locations are accessed via an un-named road or driveway, that road should be named, and numbers assigned, whether or not the road is “accepted” by the municipality as an official street.
  3. The sequence of numbers assigned to address locations along any street should match the sequence of the access points for those locations, with odd numbers on one side of the street and even numbers on the other (parity) and numbers on both sides increasing in the same direction.
  4. Addresses accessed from streets in neighboring communities should respect the name, numbering sequence, and parity of addresses in the neighboring community.

There are many, many situations in Massachusetts where these rules are not being followed. These situations are a significant obstacle to implementing Next Generation 911 and to public safety in general.

MassGIS is has developed a template by-law and regulation for municipal addressing, and has completed a Standard for Municipal Addressing in the Commonwealth. Once those documents are available, we will broadly publicize them; they will be available through the MassGIS website.

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