Türkiye’de demiryolu ağırlıklı kombine yük taşımacılığı olanaklarının araştırılması

If some special cases are excluded, highway transportation is the only mode used to provide the door-to-door movement of goods. Although highway transportation is used commonly, it is not suitable for freight to be carried over long distances because of its cost and environmental impacts. For this reason, more than one mode must be used to carry goods economically and safely. This kind of transportation is called multimodal transport, or inter-modal transport, or combined transport and has also been increasing in Turkey. However, in addition to the shortcomings in railway infrastructure, the deficiencies in operating the existing system prevents railways from playing an important role in combined transport. In this study, the requisities that must be brought in to improve the opportunities of combined transport in Turkey have been investigated by developing a network model. The model developed carries out simulating the freight flows consisting of various commercial goods on a multimodal network representing highway and railway modes. The existence of more than one mode between two adjacent regions is represented with parallel links. In order to model transfer of freight between transportation modes, transfer links have been formed. In addition, passenger transportation is taken into account, con-sidering that it also uses the same network. However, it is assumed that travellers determine in advance which transportation mode they will use and that there are no transfers between these transportation modes. Different cost functions are defined for passenger and freight transport. These cost functions depend on the volume of goods and the amount of passenger traffic on the link. Similarly, a cost function is associated with each transfer link. The demand for each product and passenger traffic is specified by a set of O-D matrices. The mode choice for each product and passenger traffic is also indicated by defining for each of these O-D matrices. The demand matrices for passenger transportation are determined separately for highway and railway modes. Highway passenger traffic is also divided into two groups as automobile and bus passenger. The Bell Model that estimates matrices from traffic counts was used to determine the intercity highway passenger and freight transportation matrices. For highway freight transportation, the initial matrices were formed by modelling the observed matrices obtained from roadside interviews with respect to some socioeconomic parameters, using multiple regression analysis. After these freight matrices were used as the initial matrices in Bell’s model, the other set of matrices that are consistent with the average annual daily truck traffic on 250 highway sections were determined. The matrices obtained for each freight type by using the Bell Model were also analysed statistically. The model developed by Bell was utilized to determine intercity automobile and bus travel matrices. In this case, the principles of Gravity Model were also used to form the initial matrices. After the intercity automobile and bus travel matrices were determined by using Bell’s method, statistical analyses were performed for the O-D information obtained from these matrices. In order to determine the railway freight and passenger matrices, the freigt transport database provided by TCDD and the charts of express and regional passenger trains were used. The multimodal as well as the highway and railway networks were coded, considering all link attributes such as distance, speed, time, and price. The O-D matrices obtained for all freight and passenger types were then assigned onto the related networks, taking into account the unit time values of all freight types and passengers. As a result of these assignments, the freight and passenger volumes carried on links as well as numbers of vehicles and trains were found. For each link, the numbers of vehicles and trains on the links that result from assigning the freight and passenger matrices onto the related networks were added up, and the total numbers of vehicles and trains on links were found. In conclusion, it is seen that the highway, freeway and connection links are not congested, and that some of the railway links carry freight volumes beyond their capacities. Finally, the requisites that must be brought in to improve the possibilities of combined transport in Turkey were discussed, based on the results obtained from this study.