Transportation Planning: Trip Generation

1
Transportation PlanningTrip Generation

• CE 573
• Lecture 9

2
Objectives

• Trip generation concepts and factors
• Trip generation using regression

3
Trip Generation Terminology

• Journey (a.k.a. trip) one-way movement from a
  point of origin to a point of destination to
  satisfy the need or demand for activity
• Home-based (HB) Trip Home is the origin or
  destination
• Non-Home-based (NHB) Neither end of the trip is
  the home of the traveler
• Trip Production Home end of a HB trip or origin
  end of a NHB trip

4
Trip Generation Terminology (continued)

• Trip Attraction non-home end of the HB trip and
  the destination end of the NHB trip
• Trip Generation total number of trips generated
  by households in a zone (HB and NHB), where the
  task remains to allocate NHB to various zones
• Trip chaining multiple trips are performed in
  sequence as a matter of efficiency, performing
  several activities

5
Classification of TripsTrip Purpose

• Homebased (HB)
• Work (HBW)
• School (HBS)
• Shopping (HBSH)
• Social and recreation (HBR)
• Other (HBO)
• Non-homebased (NHB)?not classified into categories

6
Classification of TripsPerson Type

• Income level
• Car ownership
• Household size
• Household structure
• group housing
• single
• family-head
• family-worker

7
Trip Generation Studies

• Household based
• Zonal based

8
Factors affecting Trip GenerationPersonal Trips
(Production)

• income
• car ownership
• household structure
• family size
• value of land
• residential density
• accessibility

9
Factors affecting Trip GenerationPersonal Trips
(Attraction)

• office space
• commercial space
• educational space
• number of employees
• type of employment (e.g., government, retail,
  industrial)

10
Growth Factor Modeling

• keep it within the context of the variables being
  forecast
• Ti aX0 bX1
• Parameters (a 2.5 trips/hh b 6 trips/hh)
• Variables (X0 no-auto hhs X1 auto hhs)
• Base year X0 500 hh and X1 500 hh
• Ti 4250 trips generated
• Forecast year everyone will own a car
• Ti 8500 trips ? based on growth factor 1000/500
  2
• Ti 6000 ? based on changes in explanatory
  variables

11
Regression Analysis and Trip GenerationZone Based

• linear relationship between number of trips
  produced or attracted by a zone and average
  socioeconomic characteristics of households in
  zone

12
Regression Analysis and Trip GenerationZone
Based (cont.)

• applicable if
• zone characteristics reflect variation in trip
  making behavior
• homogeneity
• full spectrum of household conditions
• dependent variable
• total trips
• average trips per household

13
Regression Analysis and Trip GenerationHousehold
Based

• Household-based similar to zone-based except
  households are the sample (no longer dealing with
  zone averages of household characteristics)

14
Regression Analysis and Trip GenerationHousehold
Based (cont.)

• applicable because
• reduced aggregation error?modeling the trip maker
• independent of zone boundaries
• care for
• prediction of explanatory variables
• non-linearities

15
Obtaining Zonal Totals

• Zone-based regression
• Household-based regression
• If using zone average HH characteristics
• Ti Hi hh_trip_rate(hh_sizeave, incomeave)