All countries and in particular developing countries like Turkey should make accurate investment decisions in order to make most of their limited resources. Investments to transportation are costly and they can not be directed to other areas. Therefore it is necessary to employ specific approaches and methods in their evaluation. When undertaking the evaluation of transportation investments, we observe that there is a shortage of data in particularly developing countries and an insufficient number of qualified experts. Furthermore, an organizational decentralization and a lack of coordination in the management of transportation, along with the usual interference of politicians with the process of decision-making with no scientific basis, which customarily occurs in such countries, are also in question. In this study, the aim was to define a simple, participatory and a clear method as well as a rational decision-making process to implement this method for Turkey, one of the countries suffering from most of the above-mentioned problems. This suggestion is based on suffices with the available data, and is in agreement with the applications in EU countries, also a scientific, quite simple, and participatory method. The other one is a clear decision-making process based on this method. The suggestion made was applied to a sample at the end of the study