Dual-Mode Propulsion Extends Range of High Speed Rail

Dual-mode propulsion in the form of electro-diesel and battery-electric locomotives is an established concept. Locomotives using these technologies have been in service for many years to provide a ‘last-mile’ capability for freight trains and traction capability when electric power is not available due to system failure or intentionally during engineering work on the infrastructure. In recent times, dual-mode propulsion has extended the range of commuter trains with the introduction of electro-diesel locomotives that operate with third-rail or OHL electric power, or with diesel prime mover. In similar fashion, the range of high speed trains, capable of speeds of 110 mph or greater, can be extended beyond the OHL by adopting dual-mode propulsion. There are three circumstances where dual-mode propulsion of high speed trains is appropriate. The first case is where it is desired to extend high speed rail service now beyond the existing OHL territory in an interim stage while OHL equipment is installed on the route. The second case involves the extension of high speed rail service over an existing route where it not feasible to install OHL equipment. A typical example of the second case is where most of the operation is over an electrified line and the extension is a relatively small proportion of the total trip, possibly involving running over a line that also carries freight trains. The third case is the commencement of high speed rail service on an established line that is not electrified while the line is electrified progressively or completely new electrified line is being constructed. The Paper describes the conceptual design of a dual-mode high speed train that has the capability of operating in electric mode up to 186 mph and in diesel mode up to 110 mph. The train follows contemporary European high speed EMU practice for the electric mode aspect, with the driving cars replaced by driving power tenders (mobile traction power houses). The power tenders input electrical power to the EMU train at the direct current link in the propulsion system. Hotel and auxiliary power is provided by diesel generators mounted underfloor on two EMU cars. For changeover to all-electric propulsion, the power tenders are replaced by driving trailers, which increases the seating capacity of the train. The diesel generator sets are retained in the all-electric mode to provide hotel and auxiliary power and limited input traction power for get-u-home capability in the event of failure of the OHL system.