Value for money
The cost and traffic disruption caused by installing trams, suggest a need for a better option.|
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In corridors of very high demand, trams have been seen as an elegant transit solution and as a prestigous investment. But there has been rightful shying away from their widespread use as an answer to the need for carbon emisson reductions and less street air pollution.|
If trams are too disruptive, too demanding of road space and too expensive, then there should be a better way. The environmental benefits of trams are exactly the same for trolleybuses - they too are electric, smooth, quiet and zero-emitting. But there are differences,
trolleybuses are not necessarily guided,
they run on rubber tyres,
they can have hub motors to give low, level floors that are easy to board,
they don't need the entire road to be dug up to build any tracks.
Running under 2 overhead wires, trolleybuses are in use in over 350 places around the world. They are the core transportation on the roads of Athens, Moscow, Sao Paulo, Bejing, Vancouver and Lyon.
Trolleybus systems can carry more than 12,000 people an hour, and many will be attracted to such a major transport initative. They have been proved to attract new customers - over 16% in San Francisco, Seattle and Vancouver. Major trolleybus investment in Lyon is proving hugely popular. And trolleybuses have returned to Rome, Boston and Sweden.
Part of the worldwide attraction of trolleybuses is cost. For superb passenger comfort, a new system can be installed in a fifth of the time and a fifth of the expense of a tramway. Trolleybuses are actually cheaper over the long-term than diesel buses. Virtually all new trolleybuses can be expected to last for 30 years.
New trolleybus systems can be powered by renewable energy sources, are easily installed, are flexible and can mix with other road traffic. They can be given precedence to ensure they are the preferred mode of travel. They can -
dock at stops within a few centimetres of the kerb and give level boarding
are renowned for their smooth riding qualities
have extremely low noise levels, no vibration or jerking and very smooth, powerful acceleration.
The very latest Swiss designs can carry 200 people. In France, trolleybuses are called rubber tyred trams. They have very many similarities to the steel tyred variety -
same propulsion method
same environmental benefits
same passenger comfort levels
same ability to attract car drivers and so reduce congestion, reduce pollution and create a much improved urban way of life.
They have one fundamental difference; they don't need a massive tramtrack infrastructure that rigidly imposes constraints on other traffic. Route changes, temporary adjustments and operational flexibility are all much easier with trolleybuses.
New trolleybuses represent an ideal solution to the problems of adapting historic corridors to the demands of modern living, transportation and safety. A well designed system, with the best combination of segregation, priority and adjustment, will deliver true, long lasting, travel benefits to Uxbridge Road that will mean a real improvement in quality of life for all.
Cost Comparison Table
*This uses the same cost risk criteria as TfL's published estimates.
**There is no detail publicly available of the methodology used by TfL to estimate the Cost Benefit Ratio. I have assumed some lessening for the Trolleybus system as the journey time is four minutes greater overall (7%). Although this should be counterbalanced, at least partially, by the reduction of road closures (both temporary and permanent) and property demolition involved in the Trolleybus scheme. It should be noted that the major benefits of reduction of noise and air pollution are completely the same for trolleybuses as for trams.
***Using 18m or 24m articulated vehicles.
In the column headed 'Tramway' above the figures are those that have been used in Transport for London public information reports or are mathematically derived from such figures. In some areas, however it is difficult to assess the correct figures as they have changed from one report to another and there are therefore different sets. As there is no public disclosure of the methodology for producing most of the figures, to derive a strict equivalent for a trolleybus alternative has been difficult.
Figures used for a trolleybus option in the original public report have never been changed to reflect the huge increase in projected carryings that have occurred between that report and the report to the TfL Board in March. Throughout the history of the project TfL have compared the option of a guided trolleybus system using, under road guidance cables, to the tramway option. This has greatly distorted all figures used for any trolleybus options. In this comparison, the trolleybus option is one of conventional trolleybuses manually driven.
In order to make a comparison therefore, I have taken the Tbus Group Transit Scheme costing sheet and matched the fields in this spreadsheet to give the outturn figures quoted publicly by TfL for the tramway. I have then used equivalent costs for a conventional manually driven trolleybus system to give an alternative close to the tramway.
It should be noted that the trolleybus option is not identical, as apart from Uxbridge station area, no parts of the route are closed to normal vehicular traffic. This results in 1.6 km. of equivalent two way road not being closed (or 8% of the total length of the route). Clearly this impacts on the speed of the transit system along these sections. TfL have given an estimated speed of 19 k.p.h. for the mean speed of the trams in the latest versions (although quoted up to over 21 k.p.h. in earlier versions). I have taken a mean figure of 20 k.p.h. as this fits better with one quoted fleet size of 44 trams (this is also quoted as 40 in some versions, but that simply does not cover the requirements even for 20 k.p.h., a reasonable layover for reliability at each end and for maintenance cover). An increase in journey time for the trolleybus of 4 minutes has been allowed. Assuming equal performance on 'open' segregated sections for trams and trolleybuses, this would permit the 1.6 km to be covered at a mean speed of 11 k.p.h. by the trolleybuses rather than 20 k.p.h. by the trams. 11 k.p.h. is less than 7 m.p.h. and thus allows for considerable congestion. It should be noted that the maximum length of any such 'shared route' is 610 metres (which is a little more than the distance between two stops). In practice the acceleration and deceleration of the trolleybus are likely to be slightly superior to that of the tram and therefore there is probably a greater margin available for lower speeds on these sections.
Clearly there is a reliability risk along this 8% of the route. It should be borne in mind however that the tramway also shares part of its route with general road traffic (over 7%), as well as a proportion shared with motor buses (this latter dependent on the unknown future bus network). With their auxiliary power units, trolleybuses are able to divert around obstructions, even to the extent of using alternative roads as well as other parts of the carriageway. Any obstruction on any part of the tramway (including by a problem on a tram) immediately stops the system completely along that section until the obstruction is completely removed. This could be summed up as saying that the trolleybuses may suffer delays along the same 7% of shared roadway as the trams plus their own additional 8% (a total of 15%) but trams are at risk of complete stoppage along the entire 100%. I am unaware of any research having being undertaken to estimate which is likely to have the greater reliability performance disbenefit, along the Uxbridge Road. Any statements by anyone about this aspect are therefore likely to be pure conjecture.
Text - Ashley Bruce, Cost Comparison - Gordon Mackley