**1. Introduction**

Transport systems are complex socio-technical systems that affect the social, economic, and environmental dimensions of a community [1]. In this context, transport planning is typically a decision-making process that based on rationality, aimed at defining and implementing transport system operations [2]. Transportation planning is now a fundamental support to a rational and sustainable development of the territorial system due to the increase of environmental issues and constraints, the worldwide financial crisis, and the numerous interactions of the transportation system with the social and economic contexts [3]. Strategic planning involves decisions on long-term nearly 10–20 years, capital investment programs for the realization of new infrastructures such as roads, railways, and ports, and the acquisition of vehicles and technologies [4]. So, the route selection problem is important in the metropolitan city for urban transportation planning processes, involving decisions on a medium- or long-term basis.

On the other hand, transportation development plays an essential role in a society's economy and has long-lasting effects on the financial, social, and political life of individuals and the community. It is essential to develop a transportation network that best suits the public's needs, to build a contemporary city [5]. Public transportation is one of the most important systems in transportation, especially in metropolis cities. So, evaluation of public transportation systems is a strategic decision-making problem for urban area [6]. At the same time, public transport is an essential element of urban life since it reduces car traffic and gives mobility to city residents. In addition, more use of public transport reduces emissions such as carbon dioxide. This feature has become more important due to the Kyoto Protocol came into effect [7]. It is important to consider the multifactorial evaluation of transportation projects due to these reasons.

The assessment of projects, meant here as capital investments that create transport infrastructure, supports the activity of decision makers. The assessment is deal with achieving social objectives, such as

improvement of economic efficiency, reduction of the damage on the environment, improvement of safety. In the case of public decision makers, the assessment is used as a tool to assist the process of planning transport infrastructure. Multicriteria analysis are widely used due to the simplicity it's in taking into account nonmarketable effects and qualitative criteria for these aims [8]. Multicriteria decision-making methods (MCDM) are widely used in transport planning to include in a comparative assessment of alternative projects their contributions to different evaluation criteria [9]. MCDM has gained importance as an evaluation method for transport projects and use of these methods increase day by day to evaluating transport projects such as passenger and freight transport, infrastructure investments, location decisions, etc. [10,11]. MCDM methodologies are rapidly growing in the various transportation problems [12–14]. At the same time, there are some studies using multi-objective optimization about transportation subjects [15] and solving multicriteria transportation-location problems [16]. Besides, these methods also have been applied in various area such as supply chain managemen<sup>t</sup> and supply chain performance measurement [17,18].

Route selection is one of the most important activity for the planning of the urban traffic that needs MCDM process. Because constructing a new structure or installing new systems are big investments and require large budget, there should be good planning. Briefly, route selection is a process in which selection or ranking are carried out among the alternative routes. At the same time, the route selection is named by some names such as "investment project selection" [19], "project selection" [20], "transportation planning" [21], "infrastructure projects selection" [22] or "corridor selection" [23]. The aim of route selection is to provide maximum benefit for traffic and the developing urban transportation. So, it will provide livable urban environment and city center. These investments need big resources such as large budget. Planned investments should be addressed in a wide range by the executives. Otherwise, it will be inevitable that the investment will become a waste. Therefore, this process is dependent on lot of criteria such as social effect, environmental effect, cost, demand level etc.

The monorail, which is one of the rail system investments, is also one of the major investment projects. The monorail is one of the urban public transportation systems that acts on its own line. This new system for Turkey is used in various countries such as Japan and China. But Turkey does not have this technology yet. However, this system is planned for various cities in Turkey and studies on this subject are still ongoing. Monorail has a lot of advantages such as to be independent of vehicle traffic, to be safe, to be fast, to be comfortable, to use low area, to be environmentally friendly and to have its own road among the other rail systems. Therefore, monorails have been becoming common day by day in the urban transportation worldwide. In terms of environment, it is environmentally friendly because of quietness and usage of energy. This system is alternative to the other rail systems and public mass transportation vehicles due to all these reasons. But it also has some negative aspects, such as high initial investment costs and the electric is not free. This system has high visual impact. This situation can be developed with high construction cost. It is important to select this technology, but the planning process is the most important of all. Therefore, selecting the best or the most suitable route is needed as the first step. This process is difficult due to the effects of many factors.

Selecting a route and a new system are complex problems which involve and effect the development of urban areas, use of land, future of the city or various other criteria and sub-criteria. There are various transportation types used for urban transportation such as bus, metro, private vehicle, taxi, subway, tramway and monorail etc. Monorail has been being applied in the European countries, the USA, in Asia (especially Japan and Chine) and Middle East countries such as Saudi Arabia and United Arab Emirates (UAE).

There are various studies about monorail in the literature. Kuwabara et al. [24] mentioned that monorail is an effective vehicle for urban transportation due to the short construction time and low-cost advantages. Wang [25] also talked about the short construction processes of monorail projects, the cost and the quality of the transportation. Kato et al. [26] talked about the advantages of a saddle-type monorail system and pointed out that in the coming years, driverless monorail systems would be used

more and more and system costs would be even lower. With simulation application, Sadatugu et al. [27] talked about alternative policies and scenarios for monorail. Sekitani et al. [28] mentioned a thrust-type monorail system for the solution of rugged roads, traffic congestion and air pollution, and they also described the technical characteristics of the line. Considering the rapid transportation of monorail, Kennedy [29] defined and mentioned their types and features. Kimijima et al. [30] gave information about the monorail by mentioning its active use in the place where the monorail was installed. Ghafooripour et al. [31] examined the countries with metro and monorail applications for developing countries and evaluated them in terms of cost-effectiveness. By evaluating its effectiveness in terms of user satisfaction, Das et al. [32] offered suggestions for the monorail transportation systems. Marathe and Hajian [33] pointed out that the monorail was ideal for the use in urban transportation in terms of economy, security and environmental sensitivity. Parekh et al. [34] discussed the features of the monorails which are popular in urban areas. Liu et al. [35] compared the conventional rail transport systems with the monorail system and discussed the advantages and disadvantages of monorail systems. Hussien [36] made a comparison between the monorail system and other public transportation vehicles. Li et al. [37] made a technical feasibility of suspended monorail type by analyzing the urban adaptation, capacity, specifications and construction costs. Timan [38] emphasized that monorail systems would be a suitable solution for the traffic problems in metropolitan cities. In his study, He [39] mentioned about the features of straddle-type monorail and noted the increase in its popularity day by day.

In the literature, related to this subject, there are a lot of studies focusing on route planning, route selection, local selection, station site selection, project selection and transportation planning. These studies have been carried out in various area and they examined different vehicle types. At the same time, authors of this research have conducted some studies related to this subject and they have contributed the literature with those studies. Hamurcu and Eren [40] proposed the monorail mass transportation for Turkey as first. Hamurcu and Eren [41] used multicriteria decision-making methods for monorail route selection in Ankara. Hamurcu et al. [42] used analytic hierarchy process (AHP) and 0-1 goal programming (GP) in the monorail project selection under the capacity constraints. Gür et al. [20] carried out monorail project selection for different route alternatives by using AHP and goal programming methods. Hamurcu and Eren [43], in their conference paper, used Analytic Network Process (ANP) and Similarity to Ideal Solution (TOPSIS) in order to carry out the monorail route selection in Ankara. Besides, selection of monorail technology [44], rail system projects selection in Istanbul [45], prioritization of high-speed rail projects [46], transportation planning [21] and decision-making for rail systems projects with MCDM and GP [47] are some of the studies of the authors of this article. So, multicriteria decision-making methods are today widely used in transport project studies commissioned by public bodies and city ad transportation planners.

Decision-making processes in transportation can be grouped different topic in terms of subject. Some of them and study areas are route planning for tramway [48], high-speed rail [49,50], railway [51], for highway [52]; route selection for light rail system [53–55], metro line [56,57], and bicycle [14]; location selection for metro [58]; station location selection for rail system network [59]; project selection for rail systems network [11]; transportation planning for transport network [60–65].

These studies show that transportation planning decisions are very important processes for planners and managers, are need analytic methods. Transportation planning is the process of identifying and incorporating stakeholder concerns, needs and values in the transport decision-making process. MCDM makes it possible to incorporate, account and quantify human opinion and preferences; solve decision problems taking into account tangible and intangible aspects; provide a methodology to calibrate the numeric scale for the measurement of quantitative as well as qualitative performances. In this study, using the analytic network process and TOPSIS from MCDMs, the challenges faced by planners in route design these decision processes were eliminated in this study. Use of ANP and TOPSIS hybrid from multi-criteria decision-making methods which are effective in terms of analysis, selection and ranking, are effective tools for quantitatively considering qualitative concepts.

In this study, we focus on the selection of monorail route. Sections of this study are as follows: In Section 2, research methodology is shown. In Section 3, the multi-criteria decision-making methods used in this study are explained. In Section 4, application of the route selection in Ankara is presented. Finally, the ranking of the best route selection is shown in Section 5.

### **2. Materials and Methods**

Multicriteria decision analysis has seen frequently used the last several decades. Its application in different areas has increased significantly, especially as new methods develop and as old methods improve.it has allowed for more complex decision analysis methods with technology advancement over the past couple of decades to be developed in addition to applying single MCDM methods to real-world decisions. This process with hybrid multi-criteria decision-making methods and their application has provided a whole new approach to decision analysis [66].

In this study, the research was carried out on eight monorail routes in Ankara, the capital city of Turkey. This study involved two methods related to the multi-criteria decision-making. These methods were ANP and TOPSIS which were used for the determination of the criteria and alternative routes for urban public transportation in Ankara. Ankara hasn't go<sup>t</sup> a monorail technology for urban transportation yet. Considered monorail projects were selected from expert opinions for urban transport planning. In the implementation of this research, there were four main parts (Figure 1), which were;


**Figure 1.** Research methodology.

This process was used in order to select the best monorail route. The alternative route characteristics were taken from Ankara metropolitan municipality and the criteria were determined by expert opinions and literature research.

The contribution of this study to the state-of-the-art can be summarized as follows: This study presents new example application and proposes a comprehensive multicriteria decision-making model for the route selection problem, which accounts for the criterion components reported in the literature. The proposed work is one of the first few works to investigate application of ANP and TOPSIS for evaluation of monorail projects under various criteria. Besides, this new system for Ankara will be first. Thus, selection of the best alternative route by using MCDM play an important role for sustainability and public transportation in Ankara metropolitan area.

### *2.1. Analytic Network Process (ANP)*

There ANP can improve communication and resolve conflicts, help diffusion of responsibility, and assist decision makers in understanding other members' viewpoints. These characteristics are attractive when a good decision calls for actions that may not be well-liked, such as outsourcing. The ANP can evaluate a wide range of criteria including tangible and intangible factors related to the outcome. Because ANP allows for complex interactions and influences among the various components of the decision problem, it can be seen as a better choice for studying more complex decision problems [67]. ANP brings all the decision objectives, criteria, alternatives and actors (such as decision makers, stakeholder, and influencers) into a single unified framework, and it facilitates interaction and feedback of elements (alternatives, criteria and actors) within groups (inner dependence) and between groups (outer dependence) [68]. Briefly, ANP is more concerned with network structure. In terms of advantages, it allows for dependence and includes independence and has the ability to prioritize groups or clusters of elements. Besides, it can support complex, networked decision-making with various intangible criteria [69]. ANP is often utilized in project selection, product planning, green supply chain management, and optimal scheduling problems and also transportation.

Most of the complex real-world decision problems have numerous inter-dependent elements that can be captured and processed by utilizing the feedback and interaction capabilities of an ANP model. In this regard, the ANP method was used directly or indirectly by Lee and Kim [70] in the information system project, by Meade and Presley [71] for the selection of research and development projects, by Ravi et al. [72] for the selection of the reverse logistics projects, by Büyüközkan and Öztürkcan [73] in six sigma projects selection, by Wey and Wu [74] for the selection of projects among transportation systems, by Begiˇcevi´c et al. [75] for the selection of projects at higher education institutions, by El-Abbasy et al. [76] for the selection of highway projects and by Tuzkaya and Yolver [77] for the selection of research and development projects.

To derive the global priorities of the criteria by using ANP, it is necessary first to carry out the pairwise comparison of the criteria with respect to the node representing their category and to all other criteria with which they interact or on which they have effect. Next, the principal right eigenvector of each comparison matrix is computed to obtain the local priority of every criterion [78]. In the last step, a super-matrix consisting of all the local-limiting matrices is formed for overall criteria prioritization and alternative ranking. The weighted super matrix is taken to the limit for the results.
