Collection of Transportation Demand Data

While discussing the models for transportation demand analysis it became clear that empirical data on travel behaviour and demographics are required for calibrating some of the models. Specifically the following types of data are necessary:

• Demographic data; these include
  • Income at individual, household, or regional level
  • Private transport vehicle ownership at individual, household, or regional level
  • Age distribution
  • Profession, etc.
• Travel behaviour
  • Number of trips produced per individual or household
  • Destination choice behaviour in terms of origin-destination matrix, etc.

The purpose of this section is to provide some idea as to how such data are obtained. Generally the demographic data is obtained from census studies and are modified (if the census is old) using growth patterns of the area. Transportation professionals typically are not involved in the collection of such data. However, data on trip making behaviour are collected by transportation professionals and hence their collection mechanism are described briefly here. Most of the techniques used fall under two broad classes: (i) the direct method and (ii) the indirect method.

In the direct method, data on travel behaviour is collected by directly observing the trips or by interviewing the prospective trip makers. The method of interviewing is generally referred to as home interview method or road-side interview method. The names are self-explanatory. In this method data collectors interview people on their trip making behaviour (like how many trips they make, the origins and destinations of their trips) and on certain demographic aspects. In the indirect methods are methods which rely on (i) traffic counts, observations on license plates, etc. and (ii) mathematical techniques to derive information on travel behaviour. Among the methods of this class are cordon line count based methods, link volume count based methods, ordinal information based methods, etc.

The reader may refer to Richardson et al. [#!rich1!#] and Moser and Kalton [#!mose1!#] for details on direct methods of data collection. The reader can refer to Reddy and Chakroborty [#!redd1!#,#!redd2!#] for a survey of indirect methods and relevant references.