Summary: College 5: Trip Distribution

Read the summary and the most important questions on College 5: Trip distribution

• 10 Two key principles

• What are the two key principles?

  1. Big produces/attracts more
  2. Nearby attracts more
  (independent of the analogy or chosen framework)

• 11 Definitions

• What is a distribution or deterrence function?

  Describes the relative willingness to make a trip as a function of the travel costs
  Fij=f(cij)

• What are the two requirements for distribution functions?

  1. Decreasing with travel costs
  2. Integral should be finite

• 14 Method 1: Growth models

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• What data is used in the base matrix?

  - Trip observations
  - Outcomes of (older) model
  - Calibrated using traffic counts

• Growth factor models advantages

  - Network specific peculiarities can be captured by observations
  - A base matrix is more understandable and verifiable than a model

• Growth factor models disadvantages

  - New residential zones are difficult to capture
  - Historical patterns may change over time

• Common application growth models

  - Given expected spatial development (short term)
  - Scale this adapted base year matrix to the future production and attraction using appropriate factors a and b

• 19 Method 2: Gravity model

• Gravity model assumptions:

  Number of trips between an origin and a destination zone is proportional to:
  - a production ability factor for the origin zone
  - an attraction ability factor for the destination zone
  - a factor depending on the travel costs between the zones

• Mathematical formulation gravity model

  Tij=pQiXjFij

• What is the difference between single and double constraint?

  Single is based on productions or attractions
  Double is based on both of them: Tij=abPiAjFij