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Case Study:
Albany, New York
Methodology
Procedure
The specific steps in the modeling procedure are as follows:
- For each traffic analysis zone, compute the residential development strength (RDS) as shown in Equation 1, based on:
- Potential number of new households that could be built in the zone, given developable land remaining and expected dwelling unit density;
- Median price of owner-occupied housing units in the zone, divided by the median price of all owner-occupied housing units;
- Ratio of total property tax rate per $1,000 full value in the zone to the mean property tax rate per $1,000 for all zones; and
- Number of households in the zone at the beginning of each increment.
Equation 1
Where:
|
HHPOTj |
= |
Potential number of new households that could be built in zone j. |
|
PRICERATIOj |
= |
Ratio of median price of owner-occupied housing units in zone j, to the median price of all owner-occupied housing units. |
|
TAXRATIOj |
= |
Ratio of total property tax rate per $1,000 full value in zone j to the mean property tax rate per $1,000 for all zones. |
|
HHBEGINj |
= |
Number of households in zone j at the beginning of each increment. |
|
a, b, c, d, and k |
= |
Coefficients developed from regression analysis of historical residential growth in the region. |
- Select an increment of total future household growth to allocate.
- Allocate this growth to each zone j based on the following factors (see Equation 2):
- Residential development strength of zone j;
- Employment accessibility of zone j (a function of total employment in each zone i and travel time between zones i and j); and
- A zone-specific residential calibration factor.
Equation 2
Where:
| dHHij,n |
= |
Number of households allocated to zone j for workers employed in zone i for increment n. |
| dHHtot,n |
= |
Number of households available for allocation in increment n. |
| EMPi |
= |
Fixed employment in zone i. |
| dEMPi,1…n-1 |
= |
Employment added to zone i in previous increments. |
| RDSj |
= |
Residential Development Strength of zone j. |
| tij |
= |
Peak hour travel time by primary mode between zone i and j. |
| b |
= |
Gravity model exponent for work-to-home and home-to-work trips. |
| HHCFi |
= |
Calibration factor derived from the ratio of CDRPC forecast household growth for the zone to the modeled household growth for the zone. |
- Select an increment of total future employment growth to allocate.
- (Equation 3) Allocate this employment growth to each zone j, based on:
- Employment accessibility of zone j (a function of total employment in each zone i and travel time between zones i and j);
- Residential accessibility of zone j (a function of total employment in each zone i and travel time between zones i and j); and
- A zone-specific employment calibration factor.
Equation 3
Where:
| dEMPij,n |
= |
Employment allocated to zone j based on households in zone i and other employment in zone i, for increment n. |
| HHi |
= |
Fixed households in zone i. |
| a |
= |
Gravity model exponent for home-to-other and other-to-home trips as calibrated in CDTC’s travel model. |
| s |
= |
Gravity model exponent for other-to-other trips. |
| EMPCFi |
= |
Calibration factor derived from the ratio of CDRPC forecast employment growth for the zone to the modeled employment growth for the zone. |
| Other variables are as defined in Equation 2. |
- Repeat the process from step 1 until all future household and employment growth has been allocated.
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