topic Data accuracy for emergency response in 911 GIS Questions

Data accuracy for emergency response

DavidGutierrez1 — Mon, 05 Oct 2015 22:32:53 GMT

Dear all,

I´d like to check any references you could bring me about GIS and mapping accuracy, data synchronization issues, verification of wireless information...

In short, whatever is needed to do to ensure that data meets the degree of accuracy necessary for an effective emergency response.

Thank you in advance.

Re: Data accuracy for emergency response

JoeBorgione — Mon, 05 Oct 2015 22:54:45 GMT

Not sure what you mean by references; like NENA or APCO? Perhaps you could be a little more specific.

Re: Data accuracy for emergency response

DavidGutierrez1 — Wed, 07 Oct 2015 21:54:22 GMT

Dear Joe,

Thank you very much for your interest.

A key concern of GIS technology in PSAP is data quality, integration, and

data manteinance. How to obtain accurate data, store and mantain that

databases is a paramount. I would like to get information about these

issues. I´ve checked out information from NENA, for instance "Guide to

Geographic Information Technology", but i´d like to check, if possible

another resources too.

Any other guidance about the addressed topics, and optimizing GIS usage in

PSAPs would be well recived.

Thank you very much in advance for your advice.

Kind regards.

2015-10-06 0:55 GMT+02:00 Joe Borgione <geonet@esri.com>:

GeoNet <https://community.esri.com/?et=watches.email.thread> Data accuracy
for emergency response
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Re: Data accuracy for emergency response

JoeBorgione — Fri, 09 Oct 2015 12:33:13 GMT

For the past 12 years I've done nothing but develop and maintain GIS data for 911 dispatch; so yeah, I'm familiar with the data needs of a PSAP. I don't know that I can synthesize my work in a few lines on a forum post, so again if you could be more specific.

As an example, I maintain a SDE database that allows the various cities to maintain their part of the overall database. I use replication to move edits from sde to fgdb that is used for dispatch. Data has evolved from 'accurate' street centerline to more precise address points. Boundary polygons such as cities, ispatch zones, etc are part of the mix as well. There are backups, physical and virtual machines, redundancies etc. Maybe when I retire I'll have a chance to document it...

Re: Data accuracy for emergency response

DavidGutierrez1 — Sun, 11 Oct 2015 18:46:25 GMT

Dear Joe,

I´m sure that if you document all your expertise when you retire it will be

a worth reading paper for sure!.

Thanks for sharing...

I´m specially interested on the challenges that PSAPs could face when they

start implementing GIS technologies.

For instance, NENA´s White papers addresses some issues like using

potential address ranges and lack of accuracy when plotting that

information.

The same documentation highlights the need of checking GIS datasets with

MSAG, and the need of implement ALI and GIS databases synchronization

methods. But it doesn´t explain nothing at all about these methods. The

document was edited in 2002, so i guess the content it´s not neccessary

updated.

Some questions could be:

- Potential versus Actual address ranges on street files.

Some sources highlight how geocoding is limited due to having a linear

relationship between the distance along a segment of road and the address

ranges.

How to avoid this shorcoming?. Only addressing individual structures?.

-Wich MSAG comparison products to check accuracy of GIS datasets could be

recommended?.

-Wich mechanisms could be recommended to ensure the continued accuracy and

synchronization of both ALI and GIS databases?.

Any help with this issues would be great.

Kind regards.

2015-10-09 14:34 GMT+02:00 Joe Borgione <geonet@esri.com>:

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Re: Data accuracy for emergency response

JoeBorgione — Mon, 12 Oct 2015 13:39:30 GMT

Personally, I consider the msag/ani/ali not to be a reliable data source as many organizations tout it to be. For starters, there is no spatial component to it; as a gis guy, this sends up all sorts red flags. Second, its maintained by additional organizations that are well removed from the actual data; how can someone thousands of miles away understand (or even care about) the nuances of individual communities? Third, telephone land lines are an endangered species; I got rid of mine several years ago and I can assure that my two sons, age 24 & 20 will never own one. That leads into my fourth and final argument; NG911 will negate to use of the msag/ani/ali.

Address ranges: any addressing system I've seen are based on an underlying grid system. If you address range streets based soley on existing structures, you can miss interesections. How would you reference blocks?

Accuracy versus precision is an argument that many misinterpret; geo-locating against linear features is accurate. Address points are precise. Interpolating address locations along a line will only be accurate, regardless of how much you compromise the ranges. Think of it: if you have a 200 meter long street and you have one structure on it with the house number of 100, and you range the street 100 to 100 on the even side, you will consistently geo locate that structure at the from node of the street segment. The reality may be that the house is located down a long driveway on the 'odd' side of the street towards the other end of the block. Accurate in the sense that you got the hit on the right block but hardly precise. What about mixed parity? How about the instance where the actual house number is assigned on the 'wrong block'?

Accutrate data is relatively cheap and plentiful; if you truly need precise data, you better get you checkbook out. The trick is figuring out your needs, and what you can afford.

As far as ani/ali/msag tools, there are plenty out there, and I'll let the respective sales people explain why one works better than the other. Again as a gis guy, I would look for a tool that uses the gis data as the basis to assess the quality of the msag/ani/ali.

All the best.

Re: Data accuracy for emergency response

DavidGutierrez1 — Mon, 12 Oct 2015 18:14:38 GMT

Dear Joe,

Thank you for your answer! Great input!

All the Best,

David

2015-10-12 15:40 GMT+02:00 Joe Borgione <geonet@esri.com>:

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