[sustran] Re: Electric Trolley Buses vs. Diesel

[Peter Lutman]

Dear Todd,

While you have a point about the various combinations of fuel / motive power, so many of these appear to 'gimmicks' or even actively dangerous that they hardly merit serious research. 
There are systems which clearly lead the way. Arnhem in Holland and Lyons in France use trolleybuses with car engines driving a generator for the occasional off-wire diversion. San Francisco uses batteries for the same reason, but given the 21% slopes, I doubt whether they would get a laden bus up the 1 or 24 routes. And of course Vancouver which has renewed its large fleet is another system using batteries as the Auxiliary Power Unit (APU).
In China Beijing and Guangzhou (both flat cities) also use battery APUs and, like the others mentioned, are extremely popular and efficient 'leader' systems.
In France, Nancy decided to install guided trolleybuses (steered in the suburbs) and the guidance rail system caused major problems. Even after months of testing, the guided sections of the system are slow and noisy. Caen installed a wholly guided system, so they could use a pantograph to collect the 600V power and the single guidance rail as the negative earth return. Even they have had a recent spectacular derailment causing a 2-day suspension of service. These are further examples of 'gimmicks' just to be different which can be ignored.
Economically, one needs sufficient demand to justify 6 journeys per hour over most of the system to justify the power supply infrastructure for trolleybus operation. With APUs short extensions can be tried without extending the overhead (Guangzhou serves a new suburban bus interchange successfully in this way with routes 109-112).
Visual Noise as Todd describes it, is not a negative but rather a positive element. The rails and wires for a tramway show potential users that there is public transport infrastructure and contribute to its appeal. (According to the LRTA website, when Liverpool, UK, replaced its tramway system with diesel buses only 70% of the tram patronage was retained by public transport). Similarly the overhead wires attract people to trolleybus routes which in many instances have attracted 16-20% gains in patronage when replacing diesel buses on the same route. Of course the smooth, silent, comfortable ride will also be a help in achieving this, so the Chinese experiments in Shanghai with super-capacitor electric buses which top-up their charge at every third bus stop may still improve on their diesel counterparts.
Obviously there will be many lower demand routes which can only economically be served by hydrocarbon fuelled buses. I am all in favour of clean, low sulphur diesel fuel. Again, however, the LPG/CNG/Hydrogen/Hybrid alternatives generally appear 'gimmicky' and in Swiss and USA cities where there have been spectacular explosions with some of these alternative fuels they appear to have significant safety drawbacks. Is it really worth researching modes which fail to achieve their targeted benefits and are generally avoided by most commercial bus operators? 
Richard M Soberman wrote a report considering the economic aspects of reintroducing trolley buses in Toronto (January 2009), and while some of his conclusions may be arguable (trolleybuses and their infrastructure can last three times as long as diesel vehicles) there may be useful data there. It might also be worth considering management attitudes and abilities and their impact on the economics of different modes with particular reference to Edmonton's hasty abandonment of its electric system and tearing down millions of dollars worth of infrastructure.


Peter Lutman FCILT

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  ----- Original Message ----- 
  From: Todd Edelman, Green Idea Factory 
  To: sustran-discuss at list.jca.apc.org 
  Cc: Simon Bishop ; Chris Cherry 
  Sent: Wednesday, June 17, 2009 8:48 AM
  Subject: [sustran] Re: Electric Trolley Buses vs. Diesel


  Hi Chris,

  While I am sure your paper will have have useful results, a comparison between trolley and Diesel buses only seems a little old fashioned.

  Better, it seems, would be one between those with on- or "off-board" traction, i.e. trolley buses with different sources of energy AND buses which carry their own engine, or indeed engine and motors. For the latter I am speaking of course of the various types of Diesel used in Diesel-engined buses, but also CNG/Bio-methane buses and Diesel-electrics with and without ultracapacitors. Or even methane-electrics, if they exist. There are also trolleys with supplemental engines to get through non-wired areas, but while becoming more common (see Skoda transportation) are not a true "hybrid". All of these are present in greater or lesser numbers in actual daily use, and, given the relatively short lifespan of buses, appear as new solutions so often in cities as to be almost untrackable. 

  I lived in San Francisco for a long time and found trolley buses vastly superior in terms of audible noise compared to the Diesels there, but somewhat inferior in terms of visual noise, i.e. all the wires and the poles to support them. 

  I am also curious about trolley buses and transmission-loss, i.e the relative energy efficiency of electric-powered buses in regards to the actual physical location of a power source. This sort of look of course also applies to buses with on-board power, i.e. is the fuel from recycled waste cooking oil ? (and how much energy is embedded in that) or imported across vast distances, e.g. natural gas from Russia to Western Europe....

  But also it seems that in systems with both trolley buses and Diesels, etc. the former would have higher occupancy rates as they would tend to operate more in central areas. This also affects effects.

  - T



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