A multi-attribute model to determine the best routes in public transportation

Congestion has long been a prominent problem for the traffic network of Istanbul as is the case in many other megacities around the world. Increasing number of private cars and limited public transport infrastructures have long motivated experts to come up with new methods and ideas to maximize the efficiency and effectiveness of public transportation systems while investigating both tangible and intangible effects of their decisions of passengers. Due to the unique city structure of Istanbul, having two geographically separated parts, the metropolitan area of Istanbul inhabits a variety of transportation modes, such as bus, tram, subway, ferry, and bus rapid transit (BRT) system. Transportation cost and travel time have always been considered as the two most important criteria for passengers' choice of mode. However, as a result of the increasing number of choices in public transport, and the discomfort created by crowdedness in vehicles during peak hours, comfort in travel has also become a significant factor of transportation mode choice. In this study, we developed a multi-attribute mathematical model to determine the best transportation routes in public transport. The objective function includes transportation costs, travel and commuting times, and predicted comfort levels. A Weighted Comprehensive Alternative Score (WCAS) is assigned for each feasible alternative path in which our three factors are considered separately. There are two important points to ponder about the calculation of WCAS scores. First is the approach that we compare the times, costs and discomfort levels of different alternative paths, and second is the importance or weight of each of these three factors in the WCAS formula. Normalization is considered for comparing the attributes of different alternatives by dividing the value of each attribute to the best value of that attribute among all alternative paths. Conjoint analysis is used to calculate the weight of each attribute in the WCAS formula. Using this technique the utility of each attribute and the utility of all levels of each attribute is obtained. A survey is used in this approach in which respondents are given ten sets of alternative paths and should choose the better choice in all ten questions based on their personal preference and the priority of attributes in their minds. An implementation example is conducted in Istanbul in order to illustrate the practical aspects of the proposed method. The implementation yields some meaningful and logical outcomes. For instance, while the traveling cost is constant during different times of the day for a specific alternative path, traveling time and discomfort level vary significantly due to much heavier traffic during peak hours. This difference would affect the WCAS of alternatives and would lead to change in the ranking of the alternative paths. Data required for the implementation example in this thesis is obtained from various affiliated companies of Istanbul Metropolitan Municipality (IETT, Istanbul Ulasim A.S., and Sehir Hatlari), which are responsible of bus and BRT, subway, and ferry operations respectively. This study provides a more holistic view on passengers' choice of transportation mode among available public transport services. Proposed model can be used in developing an optimal route planning system which considers the comfort as a criterion in passengers' choice in transportation mode or a simulation of passenger behavior can be conducted to identify the bottlenecks of the transportation system.