Vehicle Trip Generation from Retail, Office and Residential Developments
D O'Cinneide, R Grealy, University College Cork, IE
The factors which determine the volume of traffic from retail food superstores, offices and residential developments in Ireland are identified. Comparisons are made with the TRICS databank.
The traffic impacts of a proposed development mainly depend on the amount of vehicular traffic generated and on the receiving capacity of the adjacent road and public transport networks. Consequently, each proposed development has unique characteristics. In applying for planning permission, transportation planners typically base predictions of the traffic generated on databanks such as TRICS. Since these databanks are based on extensive traffic counts at a range of existing developments, they are generally accepted as giving reliable estimates of the expected traffic volumes. However, little independent verification is available and substantial differences between the predicted and measured traffic volumes are not uncommon.
In this paper the results of detailed investigations into the traffic impacts of new developments in Ireland are presented. UK junction models are shown to be sufficiently accurate for quantifying the road system impacts if the traffic loading from a proposed development is known. Trip generation studies are used to identify the principal factors which determine the volume of traffic from the three most common types of new development in Ireland; retail food superstores, offices and residential developments. Comparisons are made with the results obtained from the TRICS databank and some shortcomings are pointed out. Generally, TRICS was found to be sufficiently accurate for estimating traffic from office developments but substantially underestimated traffic from some types of retail and residential developments. Recommendations are made for the improved prediction of traffic generation from such developments.
Association for European Transport