Cover: South East Wales Transport Model

South East Wales Transport Model

Frequency model results

Published Sep 13, 2018

by Fay Dunkerley, James Fox, Sunil Patil

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Research Questions

  1. How does travel frequency in South East Wales vary according to the characteristics of individuals and their households?
  2. How does travel frequency in South East Wales vary between different travel purposes?

This report documents the methodology and estimation results of the frequency model components of the South East Wales Transport Model (SEWTM). Frequency models have been estimated for seven home-based tour purposes. Models were also developed for work and non-work related non-home-based tours and detours. Travel frequency is predicted by applying two linked sub-models to predict the number of tours an individual makes on an average weekday in school term time. The first sub-model predicts whether an individual makes at least one tour in a day, and the second predicts the number of tours for a given purpose, given that the individual has made at least one tour.

The socio-economic parameters that are found to be significant in explaining frequency of travel depend on the tour purpose and type but include employment status, age, household size and car availability.

Key Findings

What characteristics explain variation in travel frequency?

  • Employment status, age, household size and car availability.

How does travel frequency vary between different travel purposes?

  • There are significant differences in the average travel frequency rate for different travel purposes. Furthermore the relative importance of the variables that explain variation in travel frequency for a given travel purpose vary between travel purposes.

Employer's business travel was underreported in the household interview data

  • As a result, adjustments were made to the commute and employer's business travel frequency rates so that the balance of the two purposes is consistent with the National Trip End Model


  • The approach to estimating frequency models for education purposes needs revisiting if there are any changes to the school leaving age.
  • If further household interview data is collected interviewers should be carefully briefed on the difference between commute and employer's business travel.

Research conducted by

The research described in this report was prepared for the Welsh Government and conducted by RAND Europe.

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