14.11.2014 Views

FSUTMS Comprehensive Modeling Workshop - Cambridge ...

FSUTMS Comprehensive Modeling Workshop - Cambridge ...

FSUTMS Comprehensive Modeling Workshop - Cambridge ...

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

Gravity Model Equation<br />

T<br />

ij<br />

=<br />

P<br />

i<br />

×<br />

n<br />

∑ ( A )<br />

j Ftij<br />

K ij<br />

j = 1<br />

A<br />

j<br />

F<br />

tij<br />

K<br />

ij<br />

where:<br />

Tij<br />

= Trips from zone i to zone j<br />

Pi = Total trips sent from zone i<br />

Aj = Total trips received by zone j<br />

Ftij<br />

= Impedance (time/distance) between zone i and zone j<br />

Kij<br />

= Socioeconomic adjustment factor for interchanges<br />

n = Number of analysis zones<br />

<strong>FSUTMS</strong>--CUBE MODELING TRAINING SERIES<br />

7<br />

Friction Factors<br />

►Friction Factors (travel time factors, “ff” factors) are<br />

Impedance-Dependent Factors Used in the Gravity<br />

Model<br />

►Friction Factors are:<br />

Generated from household survey data<br />

Borrowed from another study<br />

FF for work can be generated from Census<br />

Journey-to<br />

to-Work<br />

FF for internal-external external trips can potentially be<br />

generated from roadside surveys<br />

<strong>FSUTMS</strong>--CUBE MODELING TRAINING SERIES<br />

8<br />

6-4

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!