Comparative assessment of trade model in INTRAMOD: gravity model vs transtool3 approach

Developing a reliable national freight transport model is crucial for Indonesia to support sustainable infrastructure, economic growth, as well as climate-action strategies. INTRAMOD is a National Freight Transport Model for Indonesia. It has three main steps, from generating the freight flows, developing the logistics models then assessing the transport network assignment. This paper focus on steps 1 within the INTRAMOD, covers the development of freight generation and freight distribution model, here called as trade model which represent the freight volume being transported from one zone to another zone within domestic shipment. The double constrained gravity model and the Transtool3 (TT3)-approach, are applied and compared for the PC freight trade model. The result shows that the double constrained gravity model is a more appropriate tool for estimating the freight demand at the zone level for Indonesia as it creates a better forecasting method for model use at different spatial resolutions. Moreover, a doubtful result arises when applying the TT3 approach, in which the summed GDP variables have a negative impact on trade.