2G. Traffic forecasts and monitoring

Question 1

Where can the traffic forecast be found?

Answer 1

P.E. Handbook 5.1.5 - gravity model

Question 2

What does TAZ stand for in the gravity model?

Answer 2

TAZ stands for Traffic Analysis Zone.
A Traffic Analysis Zone (TAZ) is a geographical area used in transportation planning and traffic modeling. These zones are used to segment a region into manageable units for traffic analysis, and the goal is to estimate traffic volumes, patterns, and movements between zones.

Question 3

What is the gravity model formula?

Answer 3

T’ab = (T’a) (Ab * fab * Kab) / (SUM(Ab * fab * Kab)

T’ab=totalnumberoftripsfromtrafficanalysiszone(TAZ)atoTAZb
T’a =totalnumberoftripsfromTAZa
Ab =totalnumberoftripsattractedfromTAZb
fab =distance/travelcost”frictionfactor”
Kab=estimatedparametertoensureresultsbalance

Question 4

What are the steps in calculating the gravity model question

Answer 4

1 - determine the percentages of each direction (ex. 80/20)
2 - Apply percentages to attraction / productions
3 - Add productions / attractions to existing volumes for count.