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Emergency/Disaster Symbology

September 30 2009 | 1 comment

I'm sure the team of Maryland GIS students responsible for the HSWG Symbols had the best of intentions, but I think the results demonstrate that creating symbols is an art form distinct from cartography -- and in an entirely different arena than GIS or geography, proper. The symbols are, um, awful -- inconsistent, confusing, cluttered... basically, everything mission-critical map symbology should NOT be.

So until the Harpers Ferry folks are commissioned to deliver the same goodness they did with their cartographic symbols library for the National Park Service maps (dare to dream, eh?), I'm left to wonder what a responsible cartographer is to do? Use undecipherable and counterproductive standards or develop usable, but unique symbology?

And while we're at it, what is a good symbol for a Public Warning Annunciator (what might be called an "air-raid siren" during war-time, or a "Nuclear Incident Siren" when located near a nuclear power plant)? Some I've seen show a tower radiating squiggly lines from the top (which might be great except when the annunciator is mounted on a single telephone pole as is often the case). Others imply they are used only for nuclear warnings by the use of the triangular radiation symbol (not applicable in areas with tsunami threats, not nuclear threats). ????

Thank you.

Mapping Center Answer:

Yes.  You are correct; the best of intentions does not mean that a usable product is created.  I (Mamata Akella) happened to do my Master's research on this topic.  Specifically, I tested the usability of the Homeland Security Emergency and Hazard Management Mapping Standards point symbology with 50 firefighters in California using an American National Standards Institute (ANSI) recommended open-ended testing method.  I tested a total of 28 map symbols that were relevant to the firefighting community and of the 28 tested, only 6 passed the open-ended comprehension test.  This, as you state above, is not a good thing AT ALL for mission critical maps. 

If you would like to see my research in full you can download my thesis at:

I am also attaching a PDF to this response of an article that I published in Cartography and Geographic Information Science in January of 2009 on this topic.

To answer your question about what a good symbol for a feature like a Public Warning Annunciator is, I highly recommend working with the people that are actually going to use the maps and symbols in the field.  Understanding who your audience is and how they are going to use the symbols is the very first step to creating something that is not inconsistent and confusing. 

I also found in my research that the stronger the graphic link of the pictorial symbol is to its real world referent (what it actually represents in real life), the greater the likelihood that the symbol will be easily understood by its users (this isn't rocket science, it just makes sense). 

For example, the fire hydrant symbol in the HSWG set was the only symbol that had 100% comprehension by firefighters because there was no ambiguity as to what that symbol represented.  It was a picture of a fire hydrant that actually represented a fire hydrant. 

That said, another recommendation is to keep things as simple as possible.  People who have been fighting a fire or who have responded to any other event simply do not have the time to decipher symbols on a map -- the symbols need to be clear, they need to be easily understood, and most importantly they need to help them save lives and resources.

I hope this and the other resources provided here help you with the symbol design/selection process.  It is refreshing to hear about someone, like yourself who really cares and understands that a symbol on a map can have such an impact in the real-world especially when it is being used by first responders in rescue/relief efforts.



Symbology is difficult posted by David VandenBos on Oct 2 2009 12:11PM
As a fire chief, its nice to see that this issue is being addressed by you. I'll be reading your thesis shortly (just downloaded it), but we've had similar problems with symbology. We try to use standardized symbols whenever possible (esp. NFPA symbols), but often they're too illegible for easy use.
In addition to being easily and intuitively recognizable, symbols need to be legible in a relatively compact size. Size is compounded by the fact that symbols are often read while responding to an emergency in a bouncing truck cab. Color is helpful, but difficult to read by color-blind folks (not a firefighting restriction) or under a red-light during night operations.

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