The AML that was used in this analysis is located below. The "Union" coverage is the union of the zoning, parcel, and constrained land coverages.

/* Density Calculations

&echo &off

&do count =  2 &to 6069 &by 1

&sv r20density 0

&sv r40density 0

&sv r3adensity 0

&sv r2adensity 0

&sv goodland3a 0

&sv goodland2a 0

&sv goodlandft 0

&sv goodlandtw 0

&sv roads3a 0

&sv roads2a 0

&sv roadstw 0

&sv roadsft 0

&sv constrain3a 0

&sv constrain2a 0

&sv constraintw 0

&sv constrainft 0

&sv totaldensity 0

&sv tdensity 0

&type *********UP TO %count% of 6069 *****************

clearselect

reselect union poly parcel# = %count%

res union poly zone_c = 'R-3A'

statistics union poly

sum area

end

&sv totalarea3a [show statistic 1 1]

&if [null %totalarea3a%] &then

&sv totalarea3a 0

&else

&do

res union poly const = 'Y'

statistics union poly

sum area

end

&sv constrain3a [show statistic 1 1]

&if [null %constrain3a%] &then

&sv constrain3a 0

&sv goodland3a = %totalarea3a% - %constrain3a%

&sv prelimdensity3a = %goodland3a% / 130542

&if %prelimdensity3a% < 1 &then

&sv finaldensity3a 0

&if %prelimdensity3a% < 2 and %prelimdensity3a% >= 1 &then

&sv finaldensity3a 1

&else

                &do

                                &sv roads3a = %goodland3a% * .15

                                &sv subland3a = %totalarea3a% - %roads3a% - %constrain3a%

                                &sv finaldensity3a = %subland3a% / 130542

                &end

clearselect

&sv r3adensity = %finaldensity3a%

&sv finaldensity3a 0

&end

clearselect

/*  ********************************************************************

reselect union poly parcel# = %count%

res union poly zone_c = 'R-2A'

statistics union poly

sum area

end

&sv totalarea2a [show statistic 1 1]

&if [null %totalarea2a%] &then

&sv totalarea2a 0

&else

&do

res union poly const = 'Y'

statistics union poly

sum area

end

&sv constrain2a [show statistic 1 1]

&if [null %constrain2a%] &then

&sv constrain2a 0

&sv goodland2a = %totalarea2a% - %constrain2a%

&sv prelimdensity2a = %goodland2a% / 87028

&if %prelimdensity2a% < 1 &then

&sv finaldensity2a 0

&else

&if %prelimdensity2a% < 2 &then

&sv finaldensity2a 1

&else

                &do

                                &sv roads2a = %goodland2a% * .15

                                &sv goodland2a = %totalarea2a% - %roads2a% - %constrain2a%

                                &sv finaldensity2a = %goodland2a% / 87028

                &end

clearselect

&sv r2adensity = %finaldensity2a%

&sv finaldensity 0

&end

/*  ********************************************************************

clearselect

reselect union poly parcel# = %count%

res union poly zone_c = 'R-40'

statistics union poly

sum area

end

&sv totalareaft [show statistic 1 1]

&if [null %totalareaft%] &then

&sv totalareaft 0

&else

&do

res union poly const = 'Y'

statistics union poly

sum area

end

&sv constrainft [show statistic 1 1]

&if [null %constrainft%] &then

&sv constrainft 0

&sv goodlandft = %totalareaft% - %constrainft%

&sv prelimdensityft = %goodlandft% / 40000

&if %prelimdensityft% < 1 &then

&sv finaldensityft 0

&else

&if %prelimdensityft% < 2 &then

&sv finaldensityft 1

&else

                &do

                                &sv roadsft = %goodlandft% * .15

                                &sv goodlandft = %totalareaft% - %roadsft% - %constrainft%

                                &sv finaldensityft = %goodlandft% / 40000

                &end

clearselect

&sv r40density = %finaldensityft%

&sv finaldensityft 0

&end

/*  ********************************************************************

clearselect

reselect union poly parcel# = %count%

res union poly zone_c = 'R-20'

statistics union poly

sum area

end

&sv totalareatw [show statistic 1 1]

&if [null %totalareatw%] &then

&sv totalareatw 0

&else

&do

res union poly const = 'Y'

statistics union poly

sum area

end

&sv constraintw [show statistic 1 1]

&if [null %constraintw%] &then

&sv constraintw 0

&sv goodlandtw = %totalareatw% - %constraintw%

&sv prelimdensitytw = %goodlandtw% / 20000

&if %prelimdensitytw% < 1 &then

&sv finaldensitytw 0

&else

&if %prelimdensitytw% < 2 &then

&sv finaldensitytw 1

&else

                &do

                                &sv roadstw = %goodlandtw% * .15

                                &sv goodlandtw = %totalareatw% - %roadstw% - %constraintw%

                                &sv finaldensitytw = %goodlandtw% / 20000

                &end

clearselect

&sv r20density = %finaldensitytw%

&sv finaldensitytw 0

&end

/*  ********************************************************************

clearselect

&sv totaldensity = %r20density% + %r40density% + %r2adensity% + %r3adensity%

reselect parcel poly parcel# = %count%

calc parcel poly goodland = %goodland3a% + %goodland2a% + %goodlandft% + %goodlandtw%

calc parcel poly roads = %roads3a% + %roads2a% + %roadstw% + %roadsft%

calc parcel poly constrain = %constrain3a% + %constrain2a% + %constraintw% + %constrainft%

&sv tdensity = [truncate %totaldensity%]

calc parcel poly density = %tdensity%

&end

&return