METHODOLOGY
Study Area and site selection The sample size for trip generation studies need not be
large. The minimum number of sites required for establishing and validating trip generation rates by the linear regression method is three. It is, however preferable to have data on at least five sites (Juette &Zeffanella, 2007). Although the minimum number of sites required from ITE is not large, this research attempts
to explore the factors affecting trip rates for condominium construction projects, so 30 sites located both in CBD and elsewhere were the sample size of this
research. The characteristics of the samples are show inTable 1.
The samples have varied characteristics and include small, medium, and large condominium projects. Moreover, the samples include both low rise and high rise condominiums, which may have different construction processes.
Data collection
Since construction sites must have records of entering and exiting vehicles for security purposes, and the recorded data are appropriate for this research, these data were collected using the interview method. The interview survey gathered entry and exit information for one week, condominium types (high rise and low rise), number of workers, number of dwelling units, and gross space in use. The data was collected by four trained surveyors during May – July 2013.