How to compute residences within walking distance of significant usable public green

For the 3-30-300 guidelines, the rule indicated by the "300" is residences must be within 300 meters (walking distance) of accessible and usable green at least 1 hectare in size. This can be computed in the Tygron Platform by creating a determination of what green qualifies as accessible and usable green, where at least 1 hectare of such green exists, what green is part of that 1 hectare structure, and what routes towards that structure exists.

Editor → Current Situation (Ribbon tab) → Overlays (Ribbon bar)

How to compute residences within walking distance of significant usable public green:

1. Create a Grid Overlay of residences.
2. Create a Grid Overlay (using a Combo Overlay is recommended) which highlights which locations are to be considered "public space", such that:
   Name: Public space
   Locations which are not publicly accessible have a value of 0.
   Locations which are publicly accessible have a value of 1.

3. 

   Add an Average Overlay, configured so that:
   Name: Green
   Attribute to average is VEGETATION_FRACTION
   Averaging distance is 0.

4. 

   Add a Combo Overlay, configured so that:
   Name: Public green
   Input A: "Public space" Overlay.
   Input B:"Green" Overlay.
   Formula: AND(A, GT(B, 0))

5. 

   Add an Average Overlay, configured so that:
   Name: Fraction of green nearby
   Input is a Grid Input Overlay.
   Input: The "Public green" Overlay.
   Averaging distance is 80.

6. 

   Add a Combo Overlay, configured so that:
   Name: Amount of green nearby
   Input A: The "Fraction of green nearby" Overlay.
   Formula: MUL(A, MUL(POW(80, 2), 3.14159))

7. 

   Add a Combo Overlay, configured so that:
   Name: 1 hectare of green
   Input A: The "Amount of green nearby" Overlay.
   Formula: GTE(A, 10000)

8. 

   Add an Average Overlay configured so that:
   Name: Environment of large green areas
   Input is a Grid Input Overlay.
   Input: The "1 hectare of green" Overlay.
   Averaging distance is 80.

9. 

   Add a Combo Overlay, configured so that:
   Name: Large green areas
   Input A: The "Public green" Overlay.
   Input B: The "Environment of large green areas" Overlay.
   Formula: AND(A, GT(B, 0))
10. Add a Travel Distance Overlay configured using the wizard such that:
    Destinations grid: based on grid overlay "Large green areas".
    Destination threshold: 1.
    Max travel distance: 290.
    Distance to road: 30.
11. Traffic Types: Pedestrians, Bicycles, and Cars.

12. 

    Add a Combo Overlay, configured so that:
    Name: Residences with green nearby
    Input A: The "Residences" Overlay.
    Input B: The Travel Distance Overlay.
    Formula: IF(EQ(A, 0), NO_DATA, GT(B, 0))
13. Configure the legend of the Combo Overlay to have a distinct entry for the value "0" and the value "1".

Notes

• If the Travel Distance Overlay does not properly calculate travel routes across certain Functions, such as bicycle paths or pavements, it may be neccessary to change the Function Values of those Functions, specifically the NUM_BICYCLES and the NUM_PEDESTRIANS.
• There is not yet a standardized way to define which locations do or do not qualify as a "Public space". A fair approximation would excluding the combined results of an Average Overlay directed at SOLID, and an Average Overlay directed at PRIVATE_YARD.

See also

• Demo 3-30-300 Project