Massachusetts Institute of Technology
Department of Urban Studies & Planning
Alternative strategies
Allocate Residential Development on
Commercial/Industrial Land
Yi Zhu & Wanli Fang
Thursday, May 15, 2008
11. 521Spatial Database Management and Advanced Geographic Information Systems
Massachusetts Institute of Technology
Department of Urban Studies & Planning
Flow Chart
• Evaluate the attractiveness in each grid cell
1
• Figure out the relative shortage on TAZ level
2
• Allocate development using different strategies
3
• Review the result to get some implementation
4
11. 521Spatial Database Management and Advanced Geographic Information Systems
Massachusetts Institute of Technology
Department of Urban Studies & Planning
Different strategies in algorithms
• Greedy Assignment Algorithm
– Different land development types compete for the total
amount of available land within the TAZ.
– All demands are satisfied simultaneously, therefore some of
the development may choose second even third best
location instead of the most desirable ones.
• The result of this strategy
– more likely to lead to a dispersed pattern of the same
development type, and a mixed development within
neighborhood.
11. 521Spatial Database Management and Advanced Geographic Information Systems
Massachusetts Institute of Technology
Department of Urban Studies & Planning
Different strategies in algorithms
• Neighborhood Emphasis Algorithm
– Different measurement of attractiveness, not only consider
the attractiveness of the grid itself, but also take into
account the attractiveness in adjacent grids.
– A linear process of allocation giving priority to denser
development type rather than doing allocating in parallel.
• Result of this strategy
– Deal with the preference on contiguity
– More compact development patterns, with the same
development type cluster together.
11. 521Spatial Database Management and Advanced Geographic Information Systems
Massachusetts Institute of Technology
Department of Urban Studies & Planning
Before Smoothing
After Smoothing
11. 521Spatial Database Management and Advanced Geographic Information Systems
Massachusetts Institute of Technology
Department of Urban Studies & Planning
Technical
Details of
Implementation
11. 521Spatial Database Management and Advanced Geographic Information Systems
Massachusetts Institute of Technology
Department of Urban Studies & Planning
Convert Raster to Vector
Spatial Join
Model Builder for Batch Processing
11. 521Spatial Database Management and Advanced Geographic Information Systems
Massachusetts Institute of Technology
Department of Urban Studies & Planning
Low VMT Strategy
Neighborhood Emphasis Strategy
11. 521Spatial Database Management and Advanced Geographic Information Systems
Massachusetts Institute of Technology
Department of Urban Studies & Planning
Low VMT Strategy
Neighborhood Emphasis Strategy
11. 521Spatial Database Management and Advanced Geographic Information Systems
Massachusetts Institute of Technology
Department of Urban Studies & Planning
Low VMT Strategy
Neighborhood Emphasis Strategy
11. 521Spatial Database Management and Advanced Geographic Information Systems
Massachusetts Institute of Technology
Department of Urban Studies & Planning
Low VMT Strategy
Neighborhood Emphasis Strategy
11. 521Spatial Database Management and Advanced Geographic Information Systems
Massachusetts Institute of Technology
Department of Urban Studies & Planning
Problems we encountered
• Order of allocation
– Give priority to the most dense type: is it feasible?
• Measures of attractiveness
– Determine the weights for the local attractiveness and the
average attractiveness of neighboring cells
• Grids on the borders
– On the TAZ border: The allocated results need to be merged
by grids, otherwise some of them will be erased when doing
spatial joint.
– On the Town border: allocation process will deal with
demands from other towns which are not in question.
11. 521Spatial Database Management and Advanced Geographic Information Systems
Massachusetts Institute of Technology
Department of Urban Studies & Planning
Other Methods we tried
• Polygon based allocation
– Allocate the development using the existing land use
polygons (clipped by TAZ) as the fundamental units.
• Advantages
– Consider the contiguity of development
– Reflect the spatial distribution of land supply more
precisely
• Disadvantages
– An aggregated accessibility of the polygons may not reflect
the reality as the area grows significantly larger than single
grid cell.
– Also, it adds to the complexity when reallocate the land
further into each grid.
11. 521Spatial Database Management and Advanced Geographic Information Systems
Massachusetts Institute of Technology
Department of Urban Studies & Planning
Polygon-based allocation for HT_4B
Polygon-based allocation for HT_7B
11. 521Spatial Database Management and Advanced Geographic Information Systems
Massachusetts Institute of Technology
Department of Urban Studies & Planning
Conclusions
• Efficiency of the models
– Different strategies of development can be captured by the
adopting different algorithms. (Demand)
– Good locations with higher accessibility can detected by the
model and assign to development first. (Supply)
• Implementation for zoning
– Cluster is a reasonable development in terms of land use
efficiency.
– However, to make it happen, we need zoning regulations to
provide the desired access to public transportation and
other facilities.
11. 521Spatial Database Management and Advanced Geographic Information Systems
Massachusetts Institute of Technology
Department of Urban Studies & Planning
VMT Estimation
• Each cell in the grid has a
value representative of the
total meters traveled one-way
for an “average” (non-work)
trip for a single household.
• Non-Work VMT = Average
Non work trip distance
(tripmerge) * No of households
(hshlds_250m) * 4.18
trips/household
11. 521Spatial Database Management and Advanced Geographic Information Systems
Massachusetts Institute of Technology
Department of Urban Studies & Planning
11. 521Spatial Database Management and Advanced Geographic Information Systems
Massachusetts Institute of Technology
Department of Urban Studies & Planning
11. 521Spatial Database Management and Advanced Geographic Information Systems
Massachusetts Institute of Technology
Department of Urban Studies & Planning
11. 521Spatial Database Management and Advanced Geographic Information Systems