Message from the Guest Editor - Stefan Östlund

Rail and road electrification, what can they learn from each other?


This newsletter presents two papers that explore the possibilities of battery and fuel cell based electric railroad traction. One of the main reasons for introducing batteries and fuel cells for rail operation is the relatively high investment cost of the catenary system, especially on railroad lines with sparse train operations. Battery and fuel cell powered vehicles have been for a long time important technologies for road vehicles where battery powered vehicles as well as different kinds of hybrids are relatively common today. Even though battery powered rail vehicles have been used historically for special purposes like shunting, this is partly a new technological link from road-vehicle electrification to rail-vehicle electrification.

A similar link from rail to road can be observed when it comes to heavy road transportation.  In Sweden, the world’s first electrified road was inaugurated in June 2016. The system has many similarities to overhead catenary systems for railroads and trams but has two wires since there is no rail for the return current. In rail operation, trains are controlled by signaling systems not only to avoid accidents, but also to utilize the existing track capability optimally. In a similar way, heavy trucks utilizing a catenary system require a form of multipurpose signaling and control system. This system must control charging of onboard energy storage systems and handle possible limitations in the electric power system that could limit the vehicles’ performance.  As for most railroad power supply systems, it is likely that electric power systems feeding future electrified roads will be relatively weak with limitations in power handling capacity; thus, it will be necessary to have sufficient space between the vehicles to limit unacceptable voltage fluctuations in the road power supply system.

Since the electric power grid is rarely designed for or located close to the highways or the railroad tracks, we can also foresee limitations in the power handling capability of the distribution grid. It is thus likely that future electrified road vehicle systems, especially for heavy vehicles, must use  a signaling and control system that will control the vehicle’s movements to limit their impact on the power system. Consequently, the characteristics of road and rail systems will gradually merge and become more similar. What comes out of this is yet not possible to predict but it will open up for interesting new collaborations between “road and rail bound” actors. 


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Jin-Woo Ahn


Sheldon Williamson

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