There have been some discussions about the use of double-stack containers on railways in China. The shortage of capacity has plagued the entire industry for a long time. Let’s expand our imagination on this topic. Double-stack container railway transportation is a form of multimodal cargo transportation, in which railway trains carry two-stack containers at the same time. On the basis of the same energy consumption and operating costs, the use of double-stack container transportation can nearly double the capacity. This form was invented in the United States in 1984 and now is used in nearly 70% of US multimodal cargoes.

By using dual-stack technology, a freight train of a given length can transport approximately twice containers, which can greatly reduce the transportation cost of each container and increase the capacity. Special well wagon is used for double-stack transportation, which can reduce the required vertical clearance and lower the center of gravity of the loading train. In addition, the design of well wagon can reduce the damage during transportation and provide higher cargo security by supporting the lower container so that the door cannot be opened.

In December 2018, the first train of sea-railway combined transportation with double-stack container in China, Ningbo-Zhoushan Port to Shaoxing double-stack container train, was successfully launched, which is an exploration and important node in China’s attempt to use double-stack container technology.

Can this technology be fully applied for Eurasian rail transportation which is currently eager to expand its capacity? Focusing on the advantages of using double-stack container and current technical limitations, we interviewed several experts and scholars, and evaluated the suitability of Eurasian freight train with double-stack container based on combination of their feedback. In order to mitigate the restrained capacity, some discussions have proposed that double-stack container can be used in Eurasian rail transportation to increase the capacity. What do they think of this idea?

Professor Ms. Guo Shu-Juan from School of Transportation Engineering, Dalian Maritime University, agrees with this point of view. She said that the successful launch of the double-stack container train from Ningbo to Shaoxing is a very good precedent, which has greatly increased the capacity of the freight channel between Ningbo and Shaoxing. In the transportation industry, “Carry more and run faster”is always the key point, and many railway freight containers in foreign countries are double-stacked. It is also feasible for Eurasian freight train to use double-stack container transportation and increase its capacity.

Ms. Lu, Xiao-Juan, Lecturer from School of Economics and Management, South China Normal University holds the similar opinion that double-stack container transportation can relatively increase the rail capacity, compared with other means like opening new routes.

Mr. Ma Bin, Associate Researcher from Institute of International Studies, Fudan University said, from technical aspect, railway double-stack container transportation can increase the capacity of lines by about 38%. However, from a practical point of view, double-stack container transportation has a limited effect on mitigating the current restrained capacity of Eurasia rail transportation. It cannot solve the problems such as shortage of containers, congestion, and disruption of conventional logistics scheduling etc..

The technical and operational problems by using double-stack container in rail transportation

In case of using double-stack container in Eurasian rail transportation, what are the technical and operational problems that need to be solved urgently?

Ms. Gao Yue-E, Director of Transportation Research Department of CCTA summarized that the technical problems needed to be solved are the minimum wire height of the catenary on electrified railway running double-stack container line, the unbalanced loading caused by high center of gravity of heavy vehicles etc., as well as the existing building boundaries and the contours of bridges and tunnels in operation, such as headroom height, width, etc..

According to Ms. Guo Shu Juan, first, there is the issue of boundary height. At present, the maximum height of the loading limit for double-stack container transportation in China is 5850mm. If 2896mm-hight 40-foot container are loaded on double-layer, the stacking height of the container reaches 5792mm. In addition, the height of vehicle for the container loading surface is 290mm, plus 15 mm thickness of the newly developed locking device between lower and upper container. Finally, the height after loading reaches 6097mm, which exceeds the maximum loading height of 247mm.

“Second, the axle load problem. When two 20-foot and one 40-foot containers are fully loaded at the same time, it will exceed the allowed loading weight of vehicle for the double-stack container. Only the Watang-Rizhao Railway(Shanxi-Henan-Shandong freight route) and the Haolebaoji-Ji’an Railway(West Inner Mongolia-Jiangxi freight route) have axle loads of 30t, which are currently the lines with heaviest axle load in China.”

She added, “Third, the issue of the height of the center of gravity. The height of the center of gravity is stipulated to be no more than 2400mm for double-stack container transportation in China. According to the current x2k-Type container vehicle, two 20-foot and one 40-foot containers will be loaded on two layers and the height of the center of gravity exceeds the prescribed height.”

Based on the opinions of experts and scholars, it is not so difficult to draw conclusions. In the long term, the double-stack container transportation is absolutely beneficial to reducing operating costs and greatly increasing the capacity. However, due to restriction factors of boundary limitation, axle load, container specifications etc., it is not realistic to transform current railway line into double-stack container transportation in a short period.

On one hand, considering the boundary height of double-stack container, bridges and tunnels along the line need to be modified and reconstructed. On the other hand, can this mode of transportation be synchronized in the broad-gauge system in CIS countries and what about in European countries? These are the problems currently faced by Eurasia rail transportation if utilizing double-stack container, and it is worthy of further discussion and exploration.

Autor: Raphael Zhang / Lou Gong-Wei