University of Twente Student Theses


Development of trip generation equations for the Gold Coast and Sunshine Coast regions

Beilen, R.J. van (2008) Development of trip generation equations for the Gold Coast and Sunshine Coast regions.

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Abstract:The current method of modelling trip production in Veitch Lister Consulting's Trip Generation Model is to use simple linear regression with stratified household attributes included as dummy 0-1 variables. While this is effective for calculating average trip rates for various household attributes, the nature of the data is such that the assumptions of linear regression are seriously violated. This means that the usefulness of these averages applied at various levels is questionable and measures of model accuracy are not to be trusted entirely. A technique commonly cited in the literature for accommodating the assumptions of linear regression with count data is to take a log transform of those counts. However, in this case, the data is also heavy in zeros and so a log transform will actually worsen the performance. In fact there is no transformation that can 'spread out' a large number of zeros to mate data suitable for simple linear regression. Instead, Zero-Inflated Poisson and Zero-Inflated Negative Binomial models are proposed as an improvement and assume to be more effective in modelling count data heavy in zeros. These zero-inflated models however, are non-linear and thus is not possible to simply apply them at the equations zonal (aggregate) level as can be done with linear models. This report details the model assumptions, fit, diagnostics and performance for each of the six trip production purposes under the linear regression technique. The zero-inflated models are finally discussed as possible future improvements but this will need some further investigation and research.
Item Type:Essay (Bachelor)
Faculty:ET: Engineering Technology
Subject:56 civil engineering
Programme:Civil Engineering BSc (56952)
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