# Thread: ISO "Built Upon Area" Question

1. ## ISO "Built Upon Area" Question

OK ISO gurus who helped me on the needed fire flow question, now I have another.

What do they consider the "Built Upon Area" of the city for purposes of locating an engine within 1.5 miles and ladder within 2.5 miles.

If we take the "obvious" definition of the total district we protect (about 25 sq. miles) we cover just about half the land area within 1.5 road miles of the two stations.

However, in that 50% of territory is probably 85% of the structures...and I'd sure like to use 85% as the multiplier in the formulas than 50%. (Yes, I do have the aerial photography available to count the structures!)

Complicating the picture is like all of Southern New England, all the land is incorporated so you can't say "within city limits" and most of the town is 2 acre zoning, so you can build a house just about anywhere, and there is neglible park lands, so we realistically can't try and say "that land shouldn't count cause it can't be developed"

2. Simply total up the number of hydrants or the total miles of roadways. That gives you the answer to the question. You won't have hydrats or roads where there are not a lot of people. Each station then gets a 1.5 and 2.5 mile overlay of road miles the road miles are totaled or hydrants are totaled. If more than 50% of the hydrants or road miles fall outside the 1/5 or 2.5 miles of the station with the most of either then you need more stations and/or apparatus to cover the area properly

They don't care about city limits they care about fire department boundaries.

3. Thanks for that answer KA...more math to crunch come winter

>You won't have hydrats or
roads where there are not a lot of people

Hydrant's your correct on...roads unfortunately are a different matter -- just a legacy of the old New England cow-paths from colonial days. Paved roads go to every place there was an active farm back in the 1920s and 30s...there's still places you can go for a half mile or more and only have one house.

On the plus side, the more preliminary numbers I work up, the more convinced I become a 5 district wide is a no-brainer, and a 4 is possible without too much more work.

Matt

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