Trip Distribution

Question 1

• determines the origin or destination of trips that are generated at a given activity.

Answer 1

Trip distribution

Question 2

• is a process by which the trips generated in one zone are allocated to other zones in the study area.

Answer 2

Trip distribution

Question 3

Basic methods used for trip distribution

Answer 3

• gravity model (preferred for its use of transportation system attributes, land use characteristics, and extensive urban calibration)
• growth factor models (used more widely in the 1950s and 1960s)
• intervening opportunities (available but not widely used in practice)

Question 4

is the most widely used and most documented trip distribution model.

Answer 4

The Gravity Model

Question 5

WHAT RELATIONSHIP DOES THE FF. HAVE IN GRAVITY MODEL: Number of trips between two zones and number of trip attractions generated by zone of destination

Answer 5

• Directly Proportional Relationship

Question 6

WHAT RELATIONSHIP DOES THE FF. HAVE IN GRAVITY MODEL: Number of trips between two zones and the time of travel between the two zones

Answer 6

• Inversely Proportional Relationship

Question 7

are used to compute trip distribution when only origin-destination (O-D) data for the current year and trip generation values for the future year are available.

Answer 7

Growth factor Models

Question 8

Early Use of Growth Factor Models

Answer 8

• It was widely used when O-D data were available, but the gravity model and calibration for friction factors (F-factors) were not operational.

Question 9

Limitations of Growth Factor Models

Answer 9

• Cannot forecast traffic between zones where no current traffic exists
• Relies on current O-D matrices
• Does not account for changes in travel time between zones (unlike the gravity model)

Question 10

• A mathematical formula that proportions future trip generation estimates to each zone as a function of the product of the current trips between the two zones Tij and the growth factor of the attracting zone Gj.

Answer 10

Fratar Method

Question 11

 Appropriate if friction factors are more reliable than attraction values

Answer 11

o Singly Constrained Gravity Models

Question 12

 Appropriate if attraction values are more reliable than friction factor
 Includes additional calculation for adjusted attraction values

Answer 12

o Doubly Constrained Gravity Models

Question 13

The Most Popular Growth Factor Model:

Answer 13

Fratar Method

Question 14

A more general form of growth factor model

Answer 14

o Average Growth Factor Model:

Question 15

(not widely used)

Answer 15

• Intervening Opportunities