(Dominic) wrote in message . com...
In article ,
Tom Anderson wrote:
What's the point of trams?

I'm not having a go, i just don't really understand what's so great
about
them. Not from the heavy rail side (they're obviously much cheaper
and
more flexible, whilst smaller and slower), but from the bus side.

Yeah, why do we need trams? Here's my opinion - feel free to criticise
it:

1. Buses are as fast as trams - even with diesel engines. If Croydon
trams ran long sections on the road mixing with cars, or if London
buses ran on a proper network of properly enforced bus lanes, that
would become clear. The maximum acceleration of both buses and trams
is set by passenger comfort - I reckon both can reach that maximum.

No , the maximum acceleration of busses is set by their engine hp. For
trams you are correct however as due to the huge torque of electric motors
they could easily accelerate much faster.

2. Buses can easily rival trams at shifting passengers - just 2 of
these 180 passenger Van Hool double-artic buses carry more than a
Croydon tram:
http://www.vanhool.com/products_bus_...Categ oryID=1
They're a bit unwieldy, but so would Croydon trams be if they really
had to mix with the traffic!

And how exactly would those busses navigate around tight corners and narrow
british roads? Its not an issue for trams as the tracks guide them but if a
driver makes a mistake with one of those the bus could be all over the place.
Why do you think we don't have truck road trains like in australia?

3. Buses ride just as well as trams, if you put them on a well
surfaced road. Both can suffer from harsh braking when mixing with

And how many well surfaced roads are there in london? Or perhaps you're
suggesting spending a few hundred million on resurfacing every single road
in london that busses use with all the associated traffic chaos?

cars and pedestrians. There's nothing wrong with rubber tyres - they
allow you to apply greater tractive and braking forces. That's why
many Paris Metro trains have them.

Yes , paris metro trains designed in the 60s. These days you can do better
with steel wheels and rails aside from which rubber tyres have much greater
rolling resistance and hence use more energy/fuel.


4. Diesel buses are more environmentally friendly than electric trams.
Although buses produce more pollution at the point of use, trams
produce more pollution overall - the electricity they run on has to be
produced somewhere, and it's been through a lot of inefficient energy
conversions by the time it reaches the tram.

Err , you seem to forget that someone has to refine and transport the diesel
fuel the bus uses to the filling station. That takes energy too. And if the
electricity used by the tram is produced by nuclear or renewable sources
then the enviromental impact is negligable. And thats not even mentioning
the soot produced by diesels, so basically your argument is crap.


5. Buses could have the "wow factor" and desirability of trams, if
they were made to look more exciting. Designs like the Wright Eclipse
Gemini are heading in the right direction.

I doubt anyone gets on a bus , tram , train or any kind of public transport
just because it looks cool. They use it to get from A to B.

6. One final point - buses require no fixed infrastructure to be built
on their route. You can run them on the road - brilliant! If there are
roadworks, you drive around them!

Yeah , they can get stuck in a hour long traffic jam too just like the cars -
brilliant!

B2003

(Boltar) wrote in message . com...
(Dominic) wrote in message . com...
In article ,
Tom Anderson wrote:
What's the point of trams?

I'm not having a go, i just don't really understand what's so great
about
them. Not from the heavy rail side (they're obviously much cheaper
and
more flexible, whilst smaller and slower), but from the bus side.

Yeah, why do we need trams? Here's my opinion - feel free to criticise
it:

1. Buses are as fast as trams - even with diesel engines. If Croydon
trams ran long sections on the road mixing with cars, or if London
buses ran on a proper network of properly enforced bus lanes, that
would become clear. The maximum acceleration of both buses and trams
is set by passenger comfort - I reckon both can reach that maximum.

No , the maximum acceleration of busses is set by their engine hp. For
trams you are correct however as due to the huge torque of electric motors
they could easily accelerate much faster.

I wouldn't underrate the acceleration of buses - with poor use of the
clutch they can easily throw people off balance - that's surely
enough. But they do lack the hp for sustained hill climbing. Trams
have enough power on tap to simply keep going.

2. Buses can easily rival trams at shifting passengers - just 2 of
these 180 passenger Van Hool double-artic buses carry more than a
Croydon tram:
http://www.vanhool.com/products_bus_...Categ oryID=1
They're a bit unwieldy, but so would Croydon trams be if they really
had to mix with the traffic!

And how exactly would those busses navigate around tight corners and narrow
british roads? Its not an issue for trams as the tracks guide them but if a
driver makes a mistake with one of those the bus could be all over the place.
Why do you think we don't have truck road trains like in australia?

Those buses (and truck road trains!) couldn't get around tight
corners, and neither can trams. That's why suitable routes are chosen
for them. This shows that trams could never meet all our urban
transport needs. It's horses for courses. Send smaller buses where
only smaller buses can go. But what trams really can't navigate around
is roadworks.

3. Buses ride just as well as trams, if you put them on a well
surfaced road. Both can suffer from harsh braking when mixing with

And how many well surfaced roads are there in london? Or perhaps you're
suggesting spending a few hundred million on resurfacing every single road
in london that busses use with all the associated traffic chaos?

I wouldn't suggest that. But it'd be cheap compared with laying tram
tracks and diverting all the utilities.

cars and pedestrians. There's nothing wrong with rubber tyres - they
allow you to apply greater tractive and braking forces. That's why
many Paris Metro trains have them.

Yes , paris metro trains designed in the 60s. These days you can do better
with steel wheels and rails aside from which rubber tyres have much greater
rolling resistance and hence use more energy/fuel.

Friction factor for steel wheels on steel rails is about 0.3. Rubber
tyres on tarmac is about 0.8. You can't beat rubber tyres for a
vehicle with frequent stops, no matter what kind of traction control
you use*. You're right about the higher rolling restistance. (Unless
you don't apply traction using the wheels ie LIM, cable, rack etc!)

4. Diesel buses are more environmentally friendly than electric trams.
Although buses produce more pollution at the point of use, trams
produce more pollution overall - the electricity they run on has to be
produced somewhere, and it's been through a lot of inefficient energy
conversions by the time it reaches the tram.

Err , you seem to forget that someone has to refine and transport the diesel
fuel the bus uses to the filling station. That takes energy too. And if the
electricity used by the tram is produced by nuclear or renewable sources
then the enviromental impact is negligable. And thats not even mentioning
the soot produced by diesels, so basically your argument is crap.

I said buses produce more pollution at the point of use. As for your
argument about using nuclear or renewable sources, I wish we did.
Instead we use mostly gas to meet our Kyoto protocol targets. I would
use London's fuel cell buses to support my argument, but the hydrogen
for them wasn't produced using renewable energy. Bummer.


5. Buses could have the "wow factor" and desirability of trams, if
they were made to look more exciting. Designs like the Wright Eclipse
Gemini are heading in the right direction.

I doubt anyone gets on a bus , tram , train or any kind of public transport
just because it looks cool. They use it to get from A to B.

6. One final point - buses require no fixed infrastructure to be built
on their route. You can run them on the road - brilliant! If there are
roadworks, you drive around them!

Yeah , they can get stuck in a hour long traffic jam too just like the cars -
brilliant!
And just like the tram too if it's not in a segregated lane.

B2003