Discussion in 'transport' started by dash, Nov 29, 2006.
I bet there's someone who can...
*looks around for paulo999*
Why does a tram need an overhead power line ?
I was in Bordeaux last summer and the trams there have a third rail but don't panic 'cos only the segment beneath the tram is live (so I was told) so no one can get electrocuted (unless they're run over by the bloody tram).
The trams are also very 'cool' looking - try googling 'Bordeaux tram' in Google images.
I'm not from London and I don't commute there, nor do I even spend much time there, but I really hope TFL doesn't let plans for any tram system in the capital to get watered down and turned into a glorified bus route.
Personally though, I think they should build more Underground lines and try to keep the streets clear of extra traffic.
Some places used to use a similar system here but on occasions the 'live segment' would stick in the live condition resulting in the instant deaths of any horses that stepped on them.
Burning fuel in a large power station is much more energy-efficient than in a small diesel bus motor due to 'economies of scale', even taking account of line loss.
So it works out to be more environmentally friendly, even if you use coal, oil or gas. Of course if you can use hydro (like they do in Vancouver), then you can run your trolleybuses with no emissions at all.
In the course of a thread early in the year I worked out that three large wind turbines are enough to run a Eurostar.
Which translates to, er, shedloads of trams.
Ah, the old, "the wind, of course blows at the correct speed 365 days a year for 24 hours a day" nonsense.
As fossil fuels will be needed to plug the (many) gaps in generation, why not burn them in vehicles that are only running point to point when they're needed (e.g. cars/taxis), as opposed to trams and buses that are mostly empty most of the time?
Wind power has its drawbacks, but it doesn't warrant being rejected out of hand.
As for "empty tram" syndrome. well, I couldn't be surprised if the economics of energy are still biased in favour of public transport, if only because a regular + reliable service will encourage more people out of their inefficient and much more polluting cars.
Most cars I see being driven around in town contain just the driver. Do they count as mostly empty, most of the time?
According to most industry pundits, where a new tram system is introduced, the majority of tram passengers will be ex-bus passengers, with only a small percentage being ex-private vehicle users. In Edinburgh, the current debacle features a circular argument regarding how many bus services LRT will delete so that passengers will be forced to relocate to the tram (which is co-terminus with bus routes along virtually every inch of its route) to prop it up with revenue. In this landscape, trolley buses are simply not relevant as they would simply compete directly with grot-diesel buses. It would be far more sensible to scrap a bus fleet and replace it with smaller cleaner buses that would be more suitable to city streets designed for 15th Century transport.
Efficiency is indeed an issue in terms of encouraging people out of cars and taxis - it's just not efficient to plan a route across 2 changes of bus, starting at time chosen by the bus routing rather than dictated by when I want to arrive at my destination. Other factors such as comfort (fibreglass/nylon velour seats in an environment redolent with other folks' chatter/ MP3 hiss vs. a car interior with seating and ambience dictated by the driver) and convenience (wrestling a new stereo/boxes of files/suitcases onto/off a bus).
In this context, public transport is only effective if draconian and artificial measures (e.g. totally banning private vehicles) are used to "incentivise" its usage.
They may only contain a single occupant but they're not simply driving around and around and around whether they're needed or not so that an examination of actual passenger miles would be directly comparable.
But if a bus has even a few passengers, then its journey is evidently needed. Sooner or later seriously underused routes get trimmed back in the frequency of their services - obviously, some bus operators are more swiftly responsive than others to this.
Your small bus idea is not necessarily a bad one: it's appropriate for some routes, but not all. Not all roads in urban areas are like the 15th century streets in the Old Town of Edinburgh either.
Granted - there's a preponderance of streets like the Georgian/Edwardian ones that meander through central London, barely able to take 2 bendy bus widths.
Not many UK cities have wide open Ceaucescu-style boulevards that might be able to take a tram track down the middle.
It shouldn't be necessary to have them that wide.
You'll probably find that most of the city routes that would be likely candidates for trams may well have been the same roads over which trams ran in the first half of the 20th century, so all of the necessary road-widening and straightening was done a hundred years ago.
It's certainly the case in London. You can spot old tram routes the instant you see them.
Ah, the old "pretend I'm so stupid I've never heard of really obvious X to score point Y" nonsense.
Here, X = "electricity grid" and Y = successful attempt to portray cobbles as a religious devotee of The Car.
Irrelevant to the introduction of trolleybuses if they have a footprint similar to existing double-deckers.
So do windmills work all the time? or do electricity powered public transport schemes need to be propped up by nuclear/carbon fuels?
I take it that's a Yes to the first question and No to the second.
Not so - they really need a dedicated pathway as their manouverability is by definition strictly limited (e.g. they can only go where there's cabling making it difficuly for them to manouvre around parked vehicles).
A lot of the "old tram routes" (trams were withdrawn in London in the early 1950s) worked then because cars and taxis and buses were not as common as they are now, so trams could move unimpeded without the need for a separate "tram lane".
It might be more difficult now.
A dedicated pathway, aka a 'bus lane'.
Trolleybuses are able to travel short distances without contact with their overhead power lines thanks to onboard batteries or supercapacitors. These can be topped up during the course of the journey by regenerative braking. Hence they can get round parked vehicles, road works etc. One of their advantages over trams.
Not really true.
Blimey. You're not pretending to be stupid.
1) Studies show that plenty windmills, somewhere, are working at any given time. You know what a grid is?
2) Others have already answered this.
The manner in which the USA lost most of it's urban public transport infrastructure is one of the subjects explored in a book by Edwin Black - 'Internal Combustion'.
It is a matter of historical fact that there were criminal conspiracy charges brought against some of the purpetrators.
Our dependence upon hydrocarbon fuelled personal transportation did not come about as the result of any inherent superiority over electrically powered mass-transit systems, rather a cold, calculated and ultimately very successful campaign of 'perception management' designed to make some very rich people a lot richer.
But there are clear advantages in vehicles which have their own onboard power source rather than being reliant on electrified tracks or power cables. They can go pretty much wherever their drivers wish, and need little or no infrastructure beyond what is provided for road transport in general.
But grid power deserves another look when you're considering well-established, busy routes, due to zero emissions at street level, very little noise, lower engine maintenance costs, higher energy efficiency, and greater ease in filtering out pollutants and sequestrating CO2 at the power station.
If a trolleybus goes off piste, where do they store the bamboo pole so that the cable booms can be re-connected before the Duracells run out?
There are no 'bamboo poles' these days, Cobbles - that was years ago. The trolley booms above the bus are lowered by hydraulic rams or in some cases by cable pulleys operated from the cab. When the trolleybus manoevres back under the wires, they are simply released again, thus re-engaging the booms.
The new system in Rome has trolleybuses that can run up to 10km on batteries, so that the historic city centre can be free of overhead wires.
Looks like your train of thought on this subject has hit the buffers, Cobbles.
They look pretty cool.
Here's a vid of one in action - c/w long, lingering shot of connecting booms:
BTW, welcome to the 'boreds', Electric City.
Ah the old 'public transport can only be efficient when it's full' line.
The key measure of efficiency here is passenger miles per gallon - mpg multiplied by number of passengers.
Your SUV does - at a charitable estimate - 30mpg around town. A bus does more like 10. Now, assume (again charitably) that you have 2 people in your beloved SUV: 30mpg x 2 occupants = 60 passenger miles per gallon. Even if the bus only has six occupants at a time (6 x 10) it's equalling your passenger-mpg figure. And much as a lot of buses don't run full for much of thre time, they usually have more than six occupants...
Granted, a lot of buses are elderly and inefficient and smoky. Edinburgh's bus fleet is quite old, certainly compared to London's, which accounts for the figure you're very fond of touting (which I noticed comes from a pro-car campaigning group site anyway) about how buses actually have caused a decrease in air quality. If Edinburgh - and other cities - would get off their arses and invest in decent buses the way London has, that problem would not arise.
In other words, and as per usual, you're talking total bollocks.
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