Abstract
Among trip distribution models, The BPR type Gravity Model is the one which is the most widely used. The key issue associated with this model is a functional form of friction factor which should be calibrated in the process, and interpretation for socioeconomic factor known as K-factor(Kij) which is used to adjust the difference between observed zone-to-zone trips and the estimated trips. In this study, the BPR type Gravity Model has been fitted to 1990 O/D data for Seoul. Two type of function form for friction factor has been employed : one is a form of Generalized function and the orther is UTP function. With above two function, the parameters for travel distance(Skin-tree) are prepared. The relationship between socioeconomic factor and trips is identified by calculating and analyzing the characteristics of Kij. Consequently, both of the friction factor functions are statistically signified. However, it show an overestimation tendency when estimated with UTP function. It is found that the Generalized function is suitable for the city of Seoul, and also, in case there are a lot of trips correlatively, the socioeconomic factor is close to 1, on the other hand if it's small, it shows a bias which is dispersed around 1.
