| Variable
/ Input |
Explanation
/ Description |
| Households per Residential Acre |
This density measure excludes non-residential land and is the measure used for
the vehicle ownership model. The H/RA is for the neighborhood, not the
specific development and is looked up by the model once the TAZ is
entered. |
| (H/RA) |
| Households per
Total Acre |
This density measure
includes non-residential land and is used only in the vehicle miles
traveled model. |
| (H/RA) |
| Pedestrian/Bicycle
Friendliness |
(Only
in VMT model). Ped is the number of census blocks per hectare (street
grid), plus an adder based upon the mean year the housing was built, both
from the U.S. Census, with bonuses for traffic calming, good pedestrian
conditions, bike lanes, paths, and bike parking, whether as part of the
initial design or added later.
Pedestrian/Bicycle Friendliness = Street Grid + Year
Built + Bonuses. Street Grid = (# of census blocks)/(developed hectares).
Year Built = 0.7 if the median year built is 1939, or earlier according to
the census; 0.6 if built 1940 - 42; 0.5 if 1943 - 45; 0.4 if 1946 - 48;
0.3 if 1949 - 50; 0.2 if 1951 - 52; 0.1 if 1953 - 55; 0 if 1956 or newer.
Bonuses: traffic calming credit up to 1.0, and bike credits up to 0.5.
A fine street grid shortens routes and offers more
alternatives, and its frequent intersections slow traffic. The measure
works because older neighborhoods tend to have a fine street grid,
sidewalks, narrow streets, slower traffic and buildings closer to the
sidewalk. |
| (Ped) |
| Traffic Analysis Zone |
An area, usually between 1.5-3 times the size of a census tract used for
transportation planning. Counties use their own TAZs. For the vehicle ownership model, data for the 1099 TAZ's used by the
Metropolitan Transportation Commission for the 9 county Bay Area are used. |
| (TAZ) |
| Transit Accessibility Index |
This is a measure of the quality of transit service in an area. Some
studies use the amount of jobs which can be reached within a given amount of
time, the vehicle ownership model uses a measure of the frequency and density of
transit service. See Zonal Transit Density below. |
| (TAI) |
| Zonal Transit Density |
A type of Transit Accessibility Index,
the Zonal Transit Density is the daily average number of buses or trains per
hour times the fraction of the zone within 1/4 mi of each bus stop (or 1/2 mi of
each rail or ferry stop or station), summed for all transit routes in or near
the zone. There may be some double counting where stops are less than 1/4 mile
apart, but correcting for this would not substantially alter the order of the
TAZs nor the relative differences between zones. Therefore this measure provides
an robust assessment of transit service.
|
| Unit
Type |
You can change these cells to reflect
different unit mixes if necessary. However, be sure to accordingly change
the number of Bedrooms and Persons Per Bedroom. |
| Bedrooms |
Make sure this input corresponds to the Unit Type,
and the Persons Per Bedroom. This entry will be used to compute the
Persons per Household (P/H). |
| # of Units |
Enter the number of each type of unit. |
| Monthly Rents |
Enter the appropriate monthly rent.
This will be used to impute the Required Household Income and Income
per Person (I/P) |
| Deed Restricted? |
Enter whether units will be permanently
affordable, deed restricted units. If the development has market rate and
affordable units of the same type, enter them on a separate line item. |
| Required Household Income |
This is the estimation of the annual
income of the developments residents. For affordable housing developments,
this is imputed based on a 30% rent burden. The rent is divided by 30% and
multiplied by 12 (to convert to annual.) For market rate units, estimated
rent burden is 25% (and adjustable). In general this is a conservative
estimate (in overestimating the income of market rate units) because of the
overall high rent burdens in the Bay Area. |
| Persons
Per Bedroom |
Currently based
on standard assumptions. Can be changed if necessary. |
| Household Size |
Equals Persons per
Bedroom X Number of Bedrooms |
| (P/H) |
