| Transport Case Study no.1: Development of a new form of rail vehicle |
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In the late 1980s, Parry Associates' work on the improvement of living conditions in the developing world's burgeoning cities (see Transport Case Study 3) identified the need for affordable, reliable transport. The requirement for this to be robust, reliable, efficient and maintainable in difficult conditions led to the eventual choice of the lightweight rail mode.
It was quickly realised that energy storage on board the vehicle would enable (1) the need for continuous trackside electrification to be obviated, (2) environmental performance and fuel efficiency to be improved through regenerative braking, and (3) instantaneous high power to be available by quickly taking energy from the store. Further research identified flywheel energy storage as providing these attributes and combining them with robustness and ease of maintenance.
The development of the concept built on earlier work on trolleybuses by the Swiss firm Oerlikon, with the help of the Scottish designer of the original flywheels. With appropriate patents in place, the technology was licensed to a new company, Parry People Movers Ltd, with Parry Associates continuing in the role of project managers and engineers of the venture.
Starting in the early 1990s, a series of lightweight rail vehicles were built in Parry Associates' workshops. The first examples featured intermittent electrical supply, where the flywheel is charged by contacting an electrical supply at stations only, giving the vehicle sufficient energy to continue to the next stop where the process is repeated. This system was used for demonstrations of street tramways during the mid-1990s (see Transport Case Study 2) and for public operation by Bristol Electric Railbus between 1998 and 2000, where a PPM 35 Railbus carried over 50,000 passengers.
More recently, self-powered vehicles have been constructed; with the principal power supply coming from the flywheel, the engines (which are used to "top up" the flywheel energy) can be much smaller than on conventional diesel trains. A PPM 50 Light Railcar, now in public operation at Stourbridge (see Transport Case Study 4) where it can carry up to 50 passengers at a time up a gradient of 1 in 56, only requires a two-litre engine, yet maintains the performance of a main line train on the same route and is capable of operating on much steeper slopes.
In total, over 100,000 passengers have been carried on PPM vehicles approved to operate in public service by HM Railway Inspectorate and other rail safety bodies.
Although recent developments have been in the UK, the original intention of providing an affordable means of transport for export markets is close to realisation with the existence of a true showcase in Britain. The Parry People Movers venture has created a new form of attractive, affordable and acceptable passenger transport to meet public needs where traditional road and rail modes do not provide a viable option.
For further information see www.parrypeoplemovers.com
Transport Case Study 2: Temporary demonstrations of street tramways
Transport Case Study 3: Report to the Chief Scientific Adviser - Office of Science & Technology
Transport Case Study 4: Approval of lightweight suburban rail operation on UK national rail network
Transport Case Study 5: Design and construction of rail structures
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