Integrating underground line design with existing public transportation systems to increase transit network connectivity: Case study in Greater Cairo

doi:10.1016/j.eswa.2020.114183

Expert Systems with Applications

Volume 167, 1 April 2021, 114183

https://doi.org/10.1016/j.eswa.2020.114183 Get rights and content

Highlights

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Underground circular line selection among several alternatives, in Greater Cairo city.
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General and adaptable methodology for large scale transit networks.
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The method minimizes the number of passengers’ transfers and maximizes the service.

Abstract

Connectivity is a significant problem in large-scale transit networks because the number of transfers required to conduct a trip is considered a discomfort by transit users. This paper presents a practical solution for an underground metro line planning problem by integrating existing bus and metro networks into a single connected transit network. The proposed method aims to obviate the usual combinatorial complexity when solving a transit route design problem. It aims to increase the overall transit system connectivity by selecting a consistent and non-demand-oriented criterion for the design. The metro lines are designed by minimizing passenger transfers through the transit network according to predefined demand node pairs. The design scheme offers a set of ring route alternatives for a sizeable case study in Greater Cairo. The case study selected sixteen traffic analysis zones, an existing metro network consisting of three main lines (113.6 km long), and twelve main bus lines (487.7 km long) for analysis. TransCAD software was used as the basis for coordinating the stations and lines of both the bus and metro systems. Subsequently, a passenger transfer counting algorithm was implemented to determine the number of transfers required between stations from each origin to each destination. A passenger origin–destination transfer matrix was created using the NetBeans integrated development environment to help determine the number of transfers required to complete trips on the transit network before and after proposing the new line. Based on the evaluation, the ring lines were highly efficient at significantly decreasing passenger transfers between stations with the minimum construction cost. This study will be of value during the strategic stages of the transit line design and will assist in rapidly generating initial solutions when certain demand information is unavailable.

Introduction

Bus networks are considered the backbone of all urban public transport systems; however, owing to congested roads, the quality of service provided by buses often declines as the duration of the journey increases (Liang et al., 2020a, Owais et al., 2015). This decline in quality can be avoided by establishing rail transit systems that provide high-level (and high-quality) mobility. Rail systems have an increasingly significant function in meeting urban travel demands. However, they lack flexibility in servicing demand centers as compared to bus networks. Therefore, bus or rail systems, by themselves, cannot satisfy the current and future requirements of transit users in megacities. In cities that operate both urban rail (metro) and bus systems, a certain level of physical integration must be provided between them (Pinto et al., 2019, Ren et al., 2018, Sang et al., 2018).

Most existing bus and metro networks in major cities were constructed several years ago, with different demand coverage objectives. As a result, some passengers conduct more than one transfer to reach their desired destination. Thus, there is a need to develop a framework to evaluate the current number of transfers and to provide a line design scheme to mitigate this number. As an example, Greater Cairo (GC) is the largest urban area in Egypt, Africa, and the Middle East. It is one of the largest, fastest-growing, and densest major urban agglomerations in the world. It is the fifth-largest megacity worldwide. Such megacities are prone to continuous urban expansion and population growth; the population of GC is predicted to reach approximately 25 million by 2030 (Nations, U. (2015), 2015).

Consequently, the transportation network of GC suffers from many problems, such as congested corridors, traffic delays, and crowded transit vehicles during peak hours. In addition, its large transportation network imposes multiple transfers between transit modes and, consequently, public transport users view the network as significantly inadequate. This scenario promotes a tendency to use or buy private cars; hence, the traffic problem in the city worsens. Accordingly, the GC municipality has attempted to increase public transport facilities by constructing new metro lines (Askar & Gab-Allah, 2002).

Therefore, in this study, GC is selected as a case study. As discussed later, the layout of the GC transit network requires improvement owing to its demand-coverage insufficiency. This study aims to integrate metro and bus systems in GC by proposing a new metro line to increase transit network connectivity and increase passenger trust in public transportation. The design methodologies in existing literature are primarily demand-oriented; as such, detailed and accurate demand information is required for the design process. However, in most developing countries, such information is unavailable. In addition, these methodologies aim to design networks from scratch, rather than extending existing transit systems with implementation difficulties in large-scale scenarios. Furthermore, it would be helpful to propose a non-demand-based criterion for analyzing demand-coverage imbalances in existing transit networks. This would allow for determination of unsatisfied demand centers, and facilitate direct planning in scenarios concerning sizeable scale networks with unreliable demand information (Owais, Moussa, & Hussain, 2020). Reducing the potential number of transfers from one mode to another could reflect positively on passengers, and increase their confidence in public transport (Owais & Osman, 2018).

In this paper, an analytical model is presented for a ring metro line design, based on the use of a non-criterion objective, i.e. a passenger transfer number (PTN), to improve the integration of GC’s metro and bus networks. In the case study, the PTN was applied in the overall transit network as the main criterion for the design and evaluation of new lines. A transfer passenger origin–destination (OD) matrix was created using the NetBeans integrated development environment and Java programming language, and the existing metro and bus networks were designed using TransCAD software. The metro network consisted of three main lines, and twelve main lines were selected for the bus network. According to the network state, seven new ring metro lines were proposed and evaluated, aiming to select the optimal metro line; this approach also increased the transit network connectivity. In addition, brute force enumeration was used to examine scenarios with multiple line selections. The proposed framework avoids the combinatorial complexity of generating and evaluating routes in large-scale networks, which constitutes a significant problem for most routing design algorithms (Owais & Alshehri, 2020).

The remainder of this paper is structured as follows. Section 2 presents the literature review. Section 3 provides input data, models, and assumptions. Section 4 defines the case study. In Section 5, the analytical model of the design is discussed. Section 6 presents the results and discussion. Section 7 presents the conclusions.

Section snippets

State of the art

The overall transit connectivity can be used to determine how intermodal transportation systems should be integrated. Vuchic and Newell (1968) were perhaps the first to present an intermodal transportation system. They established the necessity for a new passenger transportation line to serve the city and minimize the passenger travel time between multimodal transportation modes. In their study, the intermodal systems were summarised as two modes of transit systems: bus and rail. More recently,

Network representation

An urban transportation network is defined as a non-directed graph G = (V, E), where V is the set of vertices (nodes) connected by the set of edges, and E is a nonempty set = {(s, e): s, e $\in$ V, c_i-j $\neq \infty$ }, in which each vertex pair (s, e) is a bi-directed edge (arc, link) with a cost c_s-e (travel time or aggregate impedance) (Owais & Alshehri, 2020). W is the set that contains every demand node pair (OD). Each vertex (s) has ADJ(s) = {e $\in$ V: (s, e) $\in$ E}, i.e. a set of nodes connected directly with one

Case study

Although our problem is presented generally, this study focussed on the GC transit network. GC, as mentioned earlier, is the most significant urban area in Egypt, Africa, and the Middle East. The government's vision for improving the transport sector in GC is represented in the GC urban transport master plan (El Araby, 2002, Huzayyin and Salem, 2013). The plans to reduce traffic congestion in GC have proceeded slower than expected. Moreover, traffic has increased much faster than projected,

Analytical model of the design

The particularity of our case study suggests the analytical model, as the introduction of any new track is a complex problem with spatial, technical, economic, political, and social aspects. In addition, financial concerns should be considered when deciding on metro line implementation. Operation and construction costs can differ significantly, owing to local conditions (Kołoś & Taczanowski, 2016). In semi-radial rail networks (Fig. 3), destinations farther away from the central business

Results and discussion

In this section, we describe the research findings in relation to the existing literature; we present additional details on the findings in the conclusion section. By considering how the number of transfers affects the total travel time of a transit trip, particularly in large urban cities, the current research developed a new transit-line optimization model that is solved using a newly proposed GA.

In a previous study (Vuchic et al., 1981), various methods of providing transit services were

Conclusion

In transportation networks operating both bus and urban rail systems, a sufficient level of integration should be ensured. Frequently, the two systems are designed with different demand coverage objectives. Whereas rail transit connects sparse demand centers with timely and efficient service, a bus system provides more flexibility in terms of reaching adjoining zones. With respect to a current transit network status, some questions can be raised. Does the existing transit network require a new

CRediT authorship contribution statement

Mahmoud Owais: Conceptualization, Methodology, Software, Validation, Writing - original draft. Abdou S. Ahmed: Formal analysis. Ghada S. Moussa: Methodology. Ahmed A. Khalil: Case study data collection, Case study analysis, Formulation, Supervising, and Reviewing.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.