The gridcells table

Geographic information partitioned into a rectangular grid of rectangular cells.

The ``improvement_value'' fields, below, indicate the value (e.g., dollars) of all buildings of a particular type that are in this grid cell. For instance, commercial_improvement_value is the total value of all commercial buildings in this grid cell. The use of ``improvement'' indicates that buildings are considered ``improvements'' over the grid cell's land value.

Column Name	Data Type	Description
grid_id	integer	Unique identifier
commercial_sqft	integer	The sum of the square footage of buildings that are classified as commercial (generally including retail and office land uses). This is not a measure of land area.
development_type_id	integer	Index into the Development Types table
distance_to_arterial	float	Units: urbansim_constants.units
distance_to_highway	float	Units: urbansim_constants.units
governmental_sqft	integer
industrial_sqft	integer
commercial_improvement_value	integer	See description, above
industrial_improvement_value	integer	See description, above
governmental_improvement_value	integer	See description, above
nonresidential_land_value	integer	Units, e.g. dollars
residential_improvement_value	integer	See description, above
residential_land_value	integer	Units, e.g. dollars
residential_units	integer	Number of residential units
relative_x	integer	X coordinate in grid coordinate system
relative_y	integer	Y coordinate in grid coordinate system
year_built	integer	e.g. 2002
plan_type_id	integer	An id indicating the plan type of the grid cell
percent_agricultural_protected_land	integer	(optional)
percent_water	integer	Percentage of this cell covered by water
percent_stream_buffer	integer	Percentage of this cell covered by stream buffer
percent_floodplain	integer	Percentage of this cell covered by flood plain
percent_wetland	integer	Percentage of this cell covered by wetland
percent_slope	integer	Percentage of this cell covered by slope
percent_open_space	integer	Percentage of this cell covered by open space
percent_public_space	integer	Percentage of this cell covered by public space
percent_roads	integer	Percentage of this cell covered by roads
percent_undevelopable	integer	(optional)
is_outside_urban_growth_boundary	boolean
is_state_land	boolean	(optional)
is_federal_land	boolean	(optional)
is_inside_military_base	boolean	(optional)
is_inside_national_forest	boolean	(optional)
is_inside_tribal_land	boolean	(optional)
zone_id	integer	Traffic analysis zone that contains this grid cell's centroid
city_id	integer	City this Grid Cell belongs to
county_id	integer	County this Grid Cell belongs to
fraction_residential_land	float	Fraction of residential land in this cell
total_nonres_sqft	integer	(optional)
total_undevelopable_sqft	integer	(optional)

• fraction_residential_land must be between 0 and 1
• commercial_sqft must be >= 0 and <= absolute_max_cell_sqft
• development_type_id must be a valid index in the development_types table
• distance_to_arterial must be >= 0 and <= absolute_max_distance
• distance_to_highway must be >= 0 and <= absolute_max_distance
• industrial_sqft must be >= 0 and <= absolute_max_cell_sqft
• governmental_sqft must be >= 0 and <= absolute_max_cell_sqft
• grid_id must be unique and > 0
• industrial_sqft must be >= 0
• commercial_improvement_value must be >= 0 and <= absolute_max_cell_dollars
• industrial_improvement_value must be >= 0 and <= absolute_max_cell_dollars
• governmental_improvement_value must be >= 0 and <= absolute_max_cell_dollars
• nonresidential_land_value must be >= 0 and <= absolute_max_cell_dollars
• residential_improvement_value must be >= 0 and <= absolute_max_cell_dollars
• residential_land_value must be >= 0 and <= absolute_max_cell_dollars
• residential_units must be must be >= 0 and <= absolute_max_cell_residential_units
• relative_x,relative_y coordinate pairs must be unique, and >= 1.
• The relative_x and relative_y columns are measured in grid cell units. They are specifically not latitude/longitude or any other universal measurement system. For example this sparse grid (6 cells in a 3x3 grid; cells are labeled with grid_id, relative_x, relative_y):

  (1,1,1)	(2,2,1)	-
  (3,1,2)	(4,2,2)	(5,3,2)
  -	-	(6,3,3)

• year_built must be less than or equal to the start date of the scenario, and must be between absolute_min_year and absolute_max_year
• plan_type must be a valid index in the plan_types table
• percent_water must be between 0 and 100
• percent_stream_buffer must be between 0 and 100
• percent_floodplain must be between 0 and 100
• percent_wetland must be between 0 and 100
• percent_slope must be between 0 and 100
• percent_open_space must be between 0 and 100
• percent_public_space must be between 0 and 100
• percent_roads must be between 0 and 100
• zone_id must be a valid id in the zones table
• city_id must be a valid index into the cities table or zero if there is no city
• county_id must be a valid index into the counties table or zero if there is no county
• gridcells with any households on them (i.e., households.grid_id = gridcell.grid_id), then the gridcell.residential_units must be greater than 0