Comparison of new peak hour trip generation rates with existing rates in the South African trip data manual

Abstract

Peak hour trip generation rates are important for the calculation of the number of trips generated by a development during a peak hour. In South Africa, trip generation rates are obtained from the trip data manual documented in the Technical Methods for Highways (THM 17). Trip generation rates can be obtained from multiple sources, TMH 17 is one of them. The TMH 17 manual acknowledges that the trip rates currently used were based on insufficient data, and in some cases international data that may not be necessarily applicable to South African traffic conditions. There is therefore, a need to develop trip generation rates that are based on local data and comparable to international data in South Africa. This paper compares a new peak hour trip generation rates with the current TMH 17 rates for office developments in Tshwane. A study area was determined by identifying office developments according to the requirements of TMH 17. Manual vehicular traffic counts were undertaken at five office building sites. Out of the five sites investigated, trip generation rates for office development at Ingersol/Lois intersection were close to the values presented in TMH 17, with the PM peak rate slightly higher than the current rate. Although valid, the results presented are preliminary and will be refined when five additional sites are included in the study to make a total sample of ten sites as per TMH 17 requirements.