Challenges of the Performance Standards of the International Finance Corporation in Financing the African Integrated High-Speed Railway Network and the Way Forward: The Case of Standard Gauge Railway in Tanzania

Financing of the African Integrated High-Speed Railway Network (AIHSRN) through Standard Gauge Railway (SGR) Projects is very expensive. As a result, most of the African countries seek financial supports from the International Financial Institutions (IFIs). However, conditions provided by the IFIs through the Performance Standards (PS) of the International Financial Corporation (IFC) increase cost of the projects and thus, it becomes a burden to most of the African countries. This study aimed to explore the causes of IFC-PS through the SGR Projects that escalate costs and how to address them. The Tanzania SGR Lot 1 Project that covered 205 km from Dar es Salaam to Morogoro was selected as a case study. The methods used for data collection involved literature review, focus group discussions and interviews. The results and findings show a gap between the IFC-PS and the National Laws and Regulations that escalates costs of the projects if funds from the IFIs were to be secured. To bridge the gap, it is recommended that the African countries should engage into negotiations with the IFIs to agree to waive IFC-PS conditions that escalate costs provided they are adequately covered in the national laws and regulations;engagement of locally established national and regional financial institutions;and the responsible government institutions in the African countries should sit together for assessment and review of the IFC-PS against the national laws and regulations.

A train timetable rescheduling approach based on multi-train tracking optimization of high-speed railways

Purpose–This paper aims to propose a train timetable rescheduling(TTR)approach from the perspective of multi-train tracking optimization based on the mutual spatiotemporal information in the high-speed railway signaling system.Design/methodology/approach–Firstly,a single-train trajectory optimization(STTO)model is constructed based on train dynamics and operating conditions.The train kinematics parameters,including acceleration,speed and time at each position,are calculated to predict the arrival times in the train timetable.A STTO algorithm is developed to optimize a single-train time-efficient driving strategy.Then,a TTR approach based on multi-train tracking optimization(TTR-MTTO)is proposed with mutual information.The constraints of temporary speed restriction(TSR)and end of authority are decoupled to calculate the tracking trajectory of the backward tracking train.The multi-train trajectories at each position are optimized to generate a timeefficient train timetable.Findings–The numerical experiment is performed on the Beijing-Tianjin high-speed railway line and CR400AF.The STTO algorithm predicts the train’s planned arrival time to calculate the total train delay(TTD).As for the TSR scenario,the proposed TTR-MTTO can reduce TTD by 60.60%compared with the traditional TTR approach with dispatchers’experience.Moreover,TTR-MTTO can optimize a time-efficient train timetable to help dispatchers reschedule trains more reasonably.Originality/value–With the cooperative relationship and mutual information between train rescheduling and control,the proposed TTR-MTTO approach can automatically generate a time-efficient train timetable to reduce the total train delay and the work intensity of dispatchers.

Developments and Prospects of Long-Span High-Speed Railway Bridge Technologies in China

With the rapid developments of the high-speed railway in China, a great number of long-span bridges have been constructed in order to cross rivers and gorges. At present, the longest main span of a constructed high-speed railway bridge is only 630 m. The main span of Hutong Yangtze River Bridge and of Wufengshan Yangtze River Bridge, which are under construction, will be much longer, at 1092 m each. In order to overcome the technical issues that originate from the extremely large dead loading and the relatively small structural stiffness of long-span high-speed railway bridges, many new technologies in bridge construction, design, materials, and so forth have been developed. This paper carefully reviews progress in the construction technologies of multi-function combined bridges in China, including com- bined highway and railway bridges and multi-track railway bridges. Innovations and practices regarding new types of bridge and composite bridge structures, such as bridges with three cable planes and three main trusses, inclined main trusses, slab-truss composite sections, and steel-concrete composite sections, are introduced. In addition, investigations into high-performance materials and integral fabrication and erection techniques for long-span railway bridges are summarized. At the end of the paper, prospects for the future development of long-span high-speed railwav bridges are provided.

Grounding Impedance Measurement of High Speed Railway Integrated Grounding System

The high-speed railway integrated grounding system is the basic guarantee for the safe and stable operation of the railway. It is the world’s largest long-distance horizontally elongated joint grounding system, which stretches the length of hundreds to thousands of kilometers, and its structure is not only different from power station and substation grounding system, but also different from the transmission line tower, lightning rod and other small grounding devices. There is little research information on the grounding impedance of high-speed railway integrated grounding system. This paper adopted 0.618 compensation method and reverse away method respectively, measured a section of high-speed railway integrated grounding system grounding impedance by JD16 and CA6425. Measurement results are in good agreement using those two type instrument. By using 0.618 compensation method, the measurement result will be gradually converged at 0.3 Ω with the increasing of current electrode distance, which is the real grounding impedance of integrated grounding system. By using reverse away method, the maximum measurement result difference is less than 0.024 Ω with the lead of current electrode distance increasing. The measurement results will be rapidly converged 0.25 Ω. The results showed that the reverse away method is helpful to shorten the length of current electrode wiring. The measurement error will be small when the current electrode wiring is longer.

Discussion on Development Mode of Large Railway Hubs in High-speed Rail Era:From Transportation Complex to Urban Complex

At present, most of China's railway hubs are developed to be transportation complexes, with some problems like unsmooth traffic circulation, mixed but disordered functions, separated spaces, etc. In high-speed rail era, high-speed railway hubs should be regarded as the catalyst to promoted urban development. The mode of urban complex should be developed, to closely connect the railway hub and the surrounding area within walking distance, so as people could get to their destinations in the most convenient way. Furthermore, it would strengthen people's aggregation, thus to bring about larger scale urban development by the successful development of urban complex.

Spatial differentiation and influence mechanism of the connection-distribution performance of urban high-speed railway hub in the Yangtze River Economic Belt

A transportation hub is the key link in the construction of the comprehensive three-dimensional transportation corridor of the Yangtze River Economic Belt,and is the basic factor responsible for the promotion of this belt.A high-speed railway hub has the“last kilometer of time-space compression”effect and is the key to building an efficient,convenient,modern,and comprehensive transportation system.This study constructed a model for measuring the connection-distribution performance of the high-speed railway hub,determined the connection-distribution performance of the urban high-speed railway hub in the Yangtze River Economic Belt,and analyzed its spatial differentiation characteristics,further revealed the influencing mechanism of the connection-distribution performance of the high-speed railway hub.The main results are as follows:(1)The connection-distribution performance of the high-speed railway hub in the Yangtze River Economic Belt presented an“olive-shaped pattern”grade structure with two small ends and a large middle section,that is,the number of high-speed railway stations with high performance and average performance was small,and the number of high-speed railway stations with good performance and medium performance was large.(2)The connection-distribution performance of the high-speed railway hub in the Yangtze River Economic Belt showed a regional differentiation pattern of“high in the east and low in the west”and“high in the north and low in the south”,and showed an urban agglomeration differentiation pattern of“high in the core areas but low in the marginal areas”;moreover,spatial differences were prominent in the distribution of nine evaluation indexes of the connection-distribution performance of the high-speed railway hub.(3)GDP,urbanization rate,city level,station passenger flow and frequency of shuttle bus were key driving factors affecting the connection-distribution performance of the high-speed railway hub.At the same time,there were significant differences in the key driving factors for the connection-distribution performance grades of high-quality,good,medium and average.