Calculating chopper rescue time with network analysis

Question

I have a layer with locations for 3 different fire stations and one hospital with a helipad. I have created a network dataset to calculate how long it takes for the firemen to arrive to various locations around the map layer.

Now I want to calculate the rescue time for the chopper from the helipad assuming it flies at a speed of 100 knots. However I'm unable to find a way to do this. I have googled and found ways to calculate flight times but none that involves the network analysis tool.

Any ideas?

EDIT: Example for what I want to do, but with chopper times instead.

Answer 1

Network Analyst uses a network of roads, because straight-line distance does not accurately represent the roads that a fire truck must drive on. This is especially true if there are geographic barriers (rivers or streams) or in a rural area with fewer roads.

In contrast, flight time analysis would not use a network because planes or helicopters can travel in straight lines. A simple Euclidean Distance raster will give you a representation of a rescue helicopter's travel time.

If there are obstacles to helicopter travel (flight exclusion zones, large skyscraper buildings, mountains), Cost Path may be a better approach, but that is likely more complex than necessary for most situations.

Answer 2

Here is a workflow you can use if you want distance rings as polygon features (instead of a raster).

Step 1: Calculate Distances

For 3 minute intervals, with 100 knots = 3086.66667 m/min:

• d₁ = 3086.66667 * 3 = 9260 [m]

• d₂ = 3086.66667 * 6 = 18520

  ⋮

• d_N = 3086.66667 * 3 * N

Step 2: Buffer Geometry

Run the Multiple Ring Buffer tool with your calculated distance values. Use your helipad point as input feature.

Step 3: Add Minutes Field

Add an integer field called Minutes to the distance ring feature class.

Run Field Calculator with the following VBScript expression:

Minutes = Round([distance] / 3086.66667)

Result