550 likes | 697 Views
Testing Out. SCENARIO 360. C. David Wickliffe GIS Specialist Rockingham Planning Commission Commission Meeting April 12, 2006. Alternate Development Scenarios. & impacts. Sample Property Analysis. Alternate Development Scenarios & Impacts. Current Status & Up to 3 alternates.
E N D
Testing Out SCENARIO360 C. David Wickliffe GIS Specialist Rockingham Planning Commission Commission Meeting April 12, 2006
Alternate Development Scenarios & impacts Sample Property Analysis
Alternate Development Scenarios & Impacts Current Status & Up to 3 alternates Impacts
indicators charts Alternate Development Scenarios • Land Use • Impervious Surfaces • Natural Resources • Unfragmented Lands • Open Space arrangement of the development • Water Use • Municipal Services Costs
Greenland Circuit Rider = David West Existing major development proposal with alternate scenarios CAD files of scenarios available Selection of the Sample Community
Sample Development Area • Approx 130 Total acres • 18 acres in Greenland • 110 acres in Rye For our Evaluation Purposes – just treat entire development as completely within Greenland
commercial and residential development – 13 single family homes 128 acres of forest Existing Conditions ‘As of Right’ – zoning compliant Dev 1 –(alternate 1 = ‘Senior Village’) Dev 2 (alternate 2 = ‘Larger Senior Village’) commercial and a major senior housing facility and townhouse buildings – 300 housing units commercial and a senior housing facility with apartment buildings – 200 housing units Alternate Development Scenarios
Process to GIS Layers Got CAD files from Developer Data Development • Impervious surfaces • Buildings • Roads • Parking lots • Land Use • Commercial • Residential • Forest • Recreational • Fragmented Land • Loss to Unfragmented Blocks • Road Centerlines • To compute road length
4 scenarios • Run simultaneously • Each has own data view • All map layers are linked so on/off status is same • All indicators, assumptions, charts exist for each scenario • But only need to make each one once –they’re automatically replicated for all scenarios • Just need to put in Differing GIS Layers (Land Use, Impervious Surfaces and Roads AND change the assumptions per scenario
Assumptions- set up • Our categories: General, Land Use, Natres, ImpSurf, Open Space, Water Use, Budget, Set Up
Writing Formulas FORMULA EDITOR • similar to MS-Excel functions • But with spatial functions, too! FORMULA WIZARD No problem for easy formulas through the Wizard – can be a steep learning curve for more difficult formulas
Charts for Indicators • Easy to set up • Not very customizable though some options Set Up/Edit
Saved Views • Arrange Similar Charts • + their indicators/assumptions CREATED SEVERAL SAVED VIEWS OF RELATED CHARTS
Look at Charts In analysis
Unfragmented land outline Our Saved Views: Unfrag OS (Unfragmented Lands & Open Space) Side by side comparison
subject_fragland Unfragmentedlands UnfragCov Unfrag OS (Unfragmented Lands & Open Space)
MaxUnFragPotNew MaxUnFragBloc MaxFragBloc
UnfragmentedLands Dynamic attribute : FragCov Indicator : MaxFragBloc Indicator : MaxUnFragBloc Acreage of Overlap with subject Fragland , 1 value for each unfragmented polygon Maximum value of FragCov Acreage of Unfragmented Lands polygon corresponding to MaxFragBloc (acreage of polygon with the largest overlap with subject fragmented lands) Acreage of Largest affected block MINUS the overlap from the Subject Fragland the ‘New’ acreage of the largest affected block with development
Our Saved Views: Unfrag OS (Unfragmented Lands & Open Space)
Subject LandUse Dynamic attribute : A2Pratio Indicator : maxOSLandu Unfrag OS (Unfragmented Lands & Open Space) Compactness Ratio , 4pA/p2, 1 value for each LU polygon (better than simple area/perimeter ratio) Area of of largest non-developed LU polygon, reselected by Land Use code Gets the Compactness Ratio for the polygon of the largest non-developed poly
Our Saved Views: Unfrag OS (Unfragmented Lands & Open Space)
Gets the Area for the polygon of the largest non-developed (Open Space) poly
Back to Community Viz Following are slides of each chart
Where’d we get sample assumptions? • Town Reports • EPA water use estimate • Just guessed – until better values are avaliable
Assumptions Figured from Town Reports Police Fire Roads Refuse
Report Generator Does 2 scenarios at a time Used for Planning Board Handouts
Possibilities To improve the Analysis Town/Watershed-wide Cumulative Indicators • The acreage and percentage coverage by impervious surfaces could be given for the subject development as well as the whole watershed. Therefore, the town could monitor the cumulative effect of each development within the watershed. More Indicators for Town Departments/Services • Get all departments that are affected by any change in population and/or development to supply any assumptions and indicators that they use – or may wish to use, to submit them to the planning board for inclusion in Scenario 360. • Planning Board is in the vanguard of the community’s control over development and growth • Could consider the many issues a development may have on • the community, • watershed • region. Require Submission of Digital Plans
Conclusions • Software has steep learning curve (this project took approx 200 hrs! • Although there were some diversions • We spent time discovering what could be done and how to do it, and included some dead ends with lost effort (but that’s why we did this evaluation) • Error messages and sometimes bombing out of program for unknown reasons • Had to remake project 3 times over, in the beginning • output is only as good as the input (as well as the process logic). • Indicator Accuracy depends on the accuracy of the input GIS layers • How legitimate are the assumptions • How well are the indicator formulas are composed. • Whether you must devise your own indicators or adopt preexisting ones can make a big difference. • Requires ArcGIS ArcView to run = $1500 software • Helps people visualize and organize development considerations and impacts • Great potential! – just needs lots of set-up time. • Once a community Analysis is ‘set-up’ - new development proposals could be fairly minor work to implement • Costs under $200 now! - perhaps best value ArcGIS extension there is
List of Charts With descriptions
Our Saved Views: Natural Resources Helpful just to visualize natural resources In relation to development Side by side comparison- map layout