Metro Transport Research Articles

Maximum Safety Regenerative Power Tracking for DC Traction Power Systems

Direct current (DC) traction power systems are widely used in metro transport systems, with running rails usually being used as return conductors. When traction current flows through the running rails, a potential voltage known as “rail potential” is generated between the rails and ground. Currently, abnormal rises of rail potential exist in many railway lines during the operation of railway systems. Excessively high rail potentials pose a threat to human life and to devices connected to the rails. In this paper, the effect of regenerative power distribution on rail potential is analyzed. Maximum safety regenerative power tracking is proposed for the control of maximum absolute rail potential and energy consumption during the operation of DC traction power systems. The dwell time of multiple trains at each station and the trigger voltage of the regenerative energy absorbing device (READ) are optimized based on an improved particle swarm optimization (PSO) algorithm to manage the distribution of regenerative power. In this way, the maximum absolute rail potential and energy consumption of DC traction power systems can be reduced. The operation data of Guangzhou Metro Line 2 are used in the simulations, and the results show that the scheme can reduce the maximum absolute rail potential and energy consumption effectively and guarantee the safety in energy saving of DC traction power systems.

Bee Inspired Novel Optimization Algorithm and Mathematical Model for Effective and Efficient Route Planning in Railway System.

Railway and metro transport systems (RS) are becoming one of the popular choices of transportation among people, especially those who live in urban cities. Urbanization and increasing population due to rapid development of economy in many cities are leading to a bigger demand for urban rail transit. Despite being a popular variant of Traveling Salesman Problem (TSP), it appears that the universal formula or techniques to solve the problem are yet to be found. This paper aims to develop an optimization algorithm for optimum route selection to multiple destinations in RS before returning to the starting point. Bee foraging behaviour is examined to generate a reliable algorithm in railway TSP. The algorithm is then verified by comparing the results with the exact solutions in 10 test cases, and a numerical case study is designed to demonstrate the application with large size sample. It is tested to be efficient and effective in railway route planning as the tour can be completed within a certain period of time by using minimal resources. The findings further support the reliability of the algorithm and capability to solve the problems with different complexity. This algorithm can be used as a method to assist business practitioners making better decision in route planning.

Models and algorithms for centralized control planes to optimize control traffic overhead

Carrier Ethernet has rapidly advanced to become an important technology in metro transport. However, the overlapping of control plane and data plane in contemporary Carrier Ethernet (CE) networks leads to complex and unmanageable networks. CE networks that use packet technologies ought to be more manageable, scalable and robust. Recently proposed network architecture, Omnipresent Ethernet (OE) recommends that the control and management plane in CE networks be decoupled from the forwarding and routing plane to overcome the problem mentioned earlier. In view of this, we investigate the possibility of a centralized control plane from OE perspective. A centralized control plane is a networking paradigm that abstracts and centralizes the control information of the network from the underlying distributed data-forwarding infrastructure. In this paper, we have focused on engineering and architectural issues related to the design of a centralized control plane for the networks built on OE Networking paradigm. Furthermore, the problem of control traffic overhead in managed networks is analyzed using an appropriate simulation model. A scheme to divide the network into smaller sub-networks is proposed so that the total control traffic is always below some threshold. An Integer Linear Program (ILP) for the controllers' placement in the partitioned network is presented. The ILP attempts to minimize the total control traffic, the total controllers' implementation cost and the overall response time in the network. Since the ILP solves the problem optimally for networks with a limited number of nodes, a heuristic approach is developed and presented for larger and real-time service-provider networks.

Facing the traffic explosion in metro transport networks with energy-sustainable architectures

The continuous growth of traffic volumes is making the consumed energy, in telecommunication networks, a critical issue. In this context, the implementation of new content distribution solutions will speed up this traffic increase. In particular, these solutions will significantly impact the traffic profile in metro networks. The current centralized traffic scenario will move toward a scenario in which the traffic exchanges would be distributed among all the nodes of the metro network. In this work, starting from a real traffic scenario, we estimate a possible traffic evolution, and we design the metro networks, according to different architectures, using integer linear programming formulations. The aim was to understand which architecture can better face the considered traffic evolution. The comparison is performed considering the energy consumption, the network setup and management, and the quality of service ensured by the architectures.

Modeling Critical Infrastructure Interdependency: The Case of the Mexico City Metro Transport System

ABSTRACT“Critical infrastructures” are exceedingly complex and highly interconnected. In order to gain a full understanding and comprehensive awareness of the risks associated with critical infrastructures it becomes essential to consider in a coherent way all the aspects that may cause a failure of such systems. That is, there is a need for a systemic approach to interdependencies among critical infrastructures. The article presents the application of a systemic safety management system (SSMS) model to interdependency modeling for the case of the Mexico City Metro transport network. The model has highlighted that interdependencies occur vertically and horizontally. Horizontal interdependency occurs at every level of recursion and can be: operational, managerial, and environmental. Vertical interdependency, on the other hand, occurs between two levels of recursion only. The SSMS model has shown the potential to be used to model interdependencies among critical infrastructures. It is hoped that the approach presented may help to gain a better understanding of critical infrastructure interdependency.

Regenerative Braking-Methods to Efficiently Use Regenerated Energy

One of the important factors of planned urbanization is a sustainable mass urban transport. All most every metro have chosen Metro Rail has the mass urban rail transport. Electricity has always been the main source of energy for urban metro transport as it has all the qualities required for mass urban transport system. Different electric systems have been used world over to supply the electricity used for Mass urban rail transport systems, popularly known as the Traction energy requirement. In this paper the traction energy supplied using 750 V DC is being dealt with. In majority of the metro rail systems, the rolling stock is equipped with regenerative brakings. In the regenerative braking the electric motor can act as a generator recovering the vehicles kinetic energy and converting it into electric energy. In metro rail since the distance between the stations is generally around 1 km, so the frequency of the braking is high so this method can be efficiently used. This highlights the different methods that be used for efficiently using the regenerated power in an a 750 V Dc traction system.

Research on Smart Urban Metro Transport Enterprise Asset Management System

Aiming at the business requirements of the urban metro transport operational asset management, this paper explored urban metro transport operational asset management system; by means of analyzing information cost of urban metro transport, smart urban metro transport operational asset management system were put forward, and the characteristics and relationship: “Asset Instrumentation, Resource Virtualization, Capacity Servitization, Business Collaboration and Decision-making Intelligentialize” in full life-cycle operational asset management process were discussed in details. Finally, system construction suggestions were given.

Stability of FIPP $p$-Cycles Under Dynamic Traffic in WDM Networks

Application opportunities associated with video, voice, and data triple-play result in a dramatic demand increase in metro transport networks, with traffic patterns becoming increasingly dynamic and difficult to predict. This is driving the need of core networks with a high degree of flexibility and multigranularities to carry traffic. We propose to investigate the question of what this means in terms of dynamic protection provisioning. In other words, we want to study how stable are the protection structures under dynamic traffic, i.e., how much and how often they need to be updated in a dynamic survivable WDM network. While most studies on the stability of protection structures have been conducted on p-cycles and link shared protection, we propose to investigate here the stability of failure-independent path-protecting (FIPP) p-cycles under dynamic traffic. For doing so, we design and develop an original scalable mathematical model that we solve using large-scale optimization tools. Numerical results show that FIPP p-cycles are remarkably stable under the evaluation of the number of required optical bypass reconfigurations under dynamic traffic.

Demonstration of error-free 25Gb/s duobinary transmission using a colourless reflective integrated modulator

To realise novel, low-cost, photonic technologies that can support 100Gb/s Ethernet in next-generation dense wavelength-division-multiplexed metro transport networks, we are developing arrayed photonic integrated circuits that leverage colourless reflective modulators. Here, we demonstrate a single-channel, hybrid reflective electroabsorption modulator-based device, showing error-free 25.3Gb/s duobinary transmission with bit-error rates less than 1 × 10(-12) over 35km of standard single-mode fibre. We further confirm the modulator's colourless operation over the ITU C-band, with a 1.2dB variation in required optical signal-to-noise ratio over this wavelength range.

Metropolitan density, energy efficiency and carbon emissions: Multi-attribute tradeoffs and their policy implications

Of all the potential benefits of urban containment, compaction, and densification, just two are the central focus here: attainment of greater energy efficiency and reduction in carbon emissions. In cities these are largely associated with the transport and building sectors. This paper probes the form-efficiency relation in the transport sector across 57 census-defined urbanized areas in the United States in 2000. Thirty-six of the forty largest are included. Increase in core area population density is correlated with modest gain in energy efficiency in the urban transport sector and modest decrease in its carbon emissions. Densification's lagged effects related to travel rationalization and growth in transit receptivity may increase overall metro transport energy efficiency beyond the degree revealed here. These impacts are associated with two off-setting negative externalities: (1) diminished housing affordability, and (2) increased roadway congestion. Each may moderate over time. Such effects are non-additive, owing to a difference of metrics. Elevated CAFE standards provoking new transport technologies may reduce total energy consumption and associated emissions ceteris paribus, lessening densification's marginal efficiency payoff while magnifying the significance of densification's opportunity costs. Categories of policy interventions to promote metro-scale energy efficiencies and emissions reductions, with and without urban densification, conclude the paper.

Determinants of Bicycle Transfer Demand at Metro Stations

Metro transit networks are constantly expanding to meet the growing travel demand that accompanies rapid urban growth. One main disadvantage of metro transport is its heavy reliance on access and egress transport and, hence, on the corresponding transfer facilities. Improvements to these transfer facilities therefore have the potential to increase use of the metro system while possibly alleviating the traffic load on the urban road network. Because bicycle transfer at metro stations—that is, using a bicycle as mode of access to or egress from the metro system—is underused, the determinants of the demand for bicycle transfer are investigated. Results and findings are valuable for designing policies aimed at improving metro ridership and for designing bicycle parking and transfer facilities at metro stations. To this end, several metro stations in Nanjing, China, were analyzed, and two stereotypical metro stations were selected for how well they represented the system. A large-scale survey was conducted on metro travelers' opinions on and use of bicycle transfer facilities, and data were collected on the current attributes of service groups, bicycle parking occupancy, and transfer mode alternatives. Furthermore, metro travelers' (latent) transfer preferences for bicycle rental facilities were investigated. Two transfer choice models were estimated to identify and quantify the determinants for bicycle transfer demand: one focuses on current walk–metro trips, and the other focuses on current bus–metro trips. The explanatory determinants are discussed, and relative weights are computed with multiple linear regression analysis.

Empathy through Accumulating Techné: Designing an Accessible Metro

ABSTRACTThis paper describes, analyses and reflects on a co-creation process between people with and without disabilities as they redesign the Brussels metro transport system over a two-decade period. Users who are visually impaired and blind become experts in the process while people without disabilities, a group of transport companies and service developers, become more empathic towards those with different needs. Our narrative reveals an inclusive design process that takes into account the particular capabilities and dispositions of people through a discussion of techné, which is described as embodied know-how enacted through daily life. This paper illustrates how people, with and without disabilities, achieve an increasingly more symmetrical negotiation as they work together towards a common goal. Techné is identified as key to engaging in a co-creation process towards developing empathy with users and discovering the nuances of users' authentic needs, and has the potential to impact design outcomes in profound ways.

100 Gigabit-per-second: Ultra-high transmission bitrate for next generation optical transport networks

Abstract Modern telecommunication networks have to provide enormous data transport capacity in order to enable the dramatic annual internet traffic growth rates. As an illustration, today some internet exchange nodes partly exhibit annual peak traffic growth rates of more than 200% due to strongly emerging data and broadband video services. This explosion of internet data and video traffic can only be assured by the implementation of the most advanced optical metro and core transport network technologies. It is likely that next generation telecommunication transport networks will be based on 100 Gigabit/s Ethernet (100 GbE) interconnections. Here we will report on the technical challenges and achievements associated with the development of ultra-high speed components and systems for serial 100 Gbit/s optical transmission. To cite this article: G. Veith et al., C. R. Physique 9 (2008).

Packet Transport System에 의한 효율적인 IPTV 분배망 구축 방안

방송과 통신의 대표적 융합서비스인 IPTV 서비스는 네트워크 상에서 QoS 보장, 멀티캐스팅 효율성, 높은 대역폭이 요구된다. 전형적인 TDM 중심의 메트로 전송 네트워크는 안정적이고 복구가 가능한 방식으로 고정된 음성 트래픽을 전송할 수 있게끔 설계되었기 때문에 폭주 특성을 지니는 데이타 트래픽을 수용하기에는 병목현상과 대역폭 낭비의 단점이 있다. 그리고 고급 하이엔드 서비스와 Best Effort의 로우엔드 서비스를 분별하지 못하여 전송 네트워크에서는 모든 데이타를 동일하게 취급을 한다. 이러한 폭주 트래픽의 증가와 QoS를 근본적으로 해결하기 위해서는 무엇보다도 새로운 전송 네트워크 설계가 절실히 요구된다. 논문에서는 TDM 중심의 메트로 전송 네트워크를 패킷 중심의 전송 네트워크로 변화 방법을 제시하고 또한 패킷 중심의 전송 네트워크의 장점과 실효성도 함께 제시한다. 그리고 패킷 중심의 전송 네트워크인 Packet Transport System 방법에 관한 기술요소와 특징들에 대해서도 함께 제시한다. 연구결과 패킷 중심의 전송 네트워크인 Packet Transport System은 기존의 TDM 특성을 수용할 뿐 아니라 QoS, 멀티캐스트, 높은 대역폭의 수용으로 효과적인 대역폭 운용과 안정적인 패킷 전송성능을 가지고 있으며, 또한 광 경로 상의 장애 발생 시 트래픽의 생존성 확보를 위한 보호 메커니즘을 고려한 알고리즘을 통해서 각 서비스 클래스별 차등화된 QoS를 보장할 수 있다. IPTV Services that is representative union service of broadcasting and telecommunication need guarantee of QoS, efficiency of multicasting, and hish bandwidth on the network. Because typical TDM based metro transport network was designed by transporting fixed voice traffic with stable and recovering method, it has a defect of bottleneck and a waste of bandwidth for acceptance of data traffic with burst feature and then all of data are treated equally at the transport network because it cannot classify between advanced high end service and best effort low end service. for completely resolving this kind of problem about increasing burst traffic and QoS issues, firstly we need to new design for transport network. This paper presents transformation method from TDM based metro transport network to packet based transport network and advantage and effectiveness of packet based transport network and also indicates technical factor and characters about method of packet transport system. As a result of research, the Packet Transport System, which is a transmission network for packet delivery, take in not only a specific character of legacy TDM but QoS, Multicast and high bandwidth, then, it is able to keep an effective bandwidth and a stabilized performance of packet transmissions. Additionally, if a fault be occurred on an optical link, the system is able to guarantee a differential QoS by an each service class using an algorithm to make certain of a traffic existence and contain a protective mechanism.

Same Wavelength Packet Switching in Optical Label Switched Networks

The authors propose a novel optical-label-swapping scheme for the same wavelength packet switching using optical carrier suppression and separation technique and without requiring any conventional wavelength converter in a scalable optical-label-switched network that carries a differential phase-shift keying modulated payload and an on-off keying modulated label. The performance of the proposed scheme is investigated using both experimental demonstration and numerical simulation. These experimental and simulation results show that the proposed optical-label-swapping scheme is suitable for the same wavelength packet switching in future scalable metro and core optical transport networks

Exposure in Traffic: Comparison of Alternatives Means of Commuting in European Studies

MS7 Symposium Title: Current Advances in Exposure and Health Effect Assessment of Traffic Exhaust Symposium Organizers: L.-J. Sally Liu and Paul English MS7-01 Introduction: Studies on exposure to traffic-generated pollution mostly focus on exposure in ambient air. Yet, exposure during the time in transit—metro, buses, cars, trams, or walking on the streets—contributes on average half of the total exposure to traffic-related pollution. Methods: Exposure to fine PM and its constituents in traffic was computed from the Project X data and measured directly in metro and street traffic in City X and in the Project Y field studies in City Y and City Z. Results: See Table.TableConclusion and Discussion: Compared with urban residential area background: 1) exposure to ultrafine particles (UFP) is highly elevated in street traffic; 2) exposure to PM2.5 is much higher in metro and bus, also high in cars on highways or streets, but similar in trains—in metro, when not in a tunnel as well; 3) exposure to black carbon (BC) is very high on busy streets; and 4) exposure to transition metals, Fe, Cu, and Mn, is ca. 5- to 10-fold higher in street traffic and 50- to 300-fold higher in metro. Higher still, metro exposures have been observed in larger and older metro systems in NYC, London, Paris, and Stockholm. Exposure in traffic forms a critical component to total and peak exposures to traffic pollution. Bus (UFP#) and metro (PM2.5 and transition metals) transport provide the highest exposures. Consequently, although individuals using urban public transport—rather than own car—do reduce traffic emissions and congestion, they may increase their own risks from traffic pollution. Efforts should, therefore, be focused at reducing passenger exposures in public transport.

Routing Framework for All-Optical DWDM Metro and Long-Haul Transport Networks With Sparse Wavelength Conversion Capabilities

In this paper, we propose a novel routing framework for all-optical dense wavelength-division-multiplexing transport networks with sparse wavelength conversion capabilities. The routing framework includes an integer linear programming formulation to handle the static lightpath establishment problem and a novel open shortest path first protocol extension that advertises the availability of wavelength usage and wavelength conversion resources. Our routing framework addresses the limitations of the extensions presented in the literature because it also includes: 1) an efficient flooding protocol that is suitable for the dynamic nature of these networks and 2) an efficient route and wavelength computation engine that minimizes connection costs without hindering the blocking probability.

INTEGRATING INTERCITY AND URBAN RAILWAYS IN BARCELONA

Railway traffic has been continuously growing in large cities in recent years, as part of the global mobility of the city. In Barcelona, for example, commuter rail demand grew from 220,000 passengers/day in 1993 to 305,000 passenger/day in 1998. To accommodate this growth (38%), several physical aspects had to improve to allow for better quality of service: a clear and urgent action needs to be undertaken in Barcelona was the remodeling of the terminal stations in the city. In 2004 a new rail infrastructure, the high speed train, will arrive and support an incremental traffic of 10 million passengers/year. Both commuter and high speed rail need a global vision and solution so that each type of service can reinforce its potential with their complementarities. This paper presents the context of rail services and network in the city of Barcelona (conventional rail and the connection with metro and public transport network), the methodology adopted for the solution (including topology and accessibility indicators, demand modeling and social cost/benefit analysis), and the conclusions of the study that define and make possible the implementation of the new network are also presented.