Does anyone know about light rail, how it works, and why it is so much more expensive than commuter rail?

[beer]

I primarily live in Austin, and there's a big debate about a proposed light rail system. I'm reading it but they never explain WHY it's so expensive, which is partialyl because I really don't know how it works. When I come back to Dallas for the summer I take the light rail all the time to work, and it seems like it works just fine to me, so I must not be understanding something here. The trains during rush hour are always beyond capacity, so why does everyone say it doesn't work? Googling hasn't really turned up much; I even checked HowStuffWorks and it's probably the only topic they haven't covered. The only thing Google has turned up is a whole bunch of anti-light-rail rhethoric but no real explanation other than 'it's too expensive."


Can anyone enlgihten me or point me in the right direction?

 

[Viper GTS]

I would assume the bulk of the expense is the power distribution since they don't carry their own power source. Of course you also have to build the tracks, the stations, and tunnels if there are any hills in the way.

Light rail here in the Portland metro area is great. There was a huge debate when it went in (I was young, I don't remember all the details, but I remember it was a big deal), but it has been quite successful & they have expanded it since.

Viper GTS

 

[beer]

How exactly do the overhead lines transmit to the train?

 

[kranky]

Dallas is one of the most successful light rail systems. From the time it opened it has been crowded. That's why they are expanding it so soon.

The primary reason light rail is expensive by comparison to commuter rail is because with light rail you usually are building the whole thing from the ground up, and commuter rail almost always uses already existing railroad lines. That's great if the railroad is already located where the transit system needs to be, but unless you have a huge network of railroad lines (like Chicago) it's unlikely. They can save a ton by not having to buy and clear property, grade it and install the entire rail system including electrical systems for propulsion.

Light rail is cheaper to operate than commuter rail, though.

 

[kranky]

Originally posted by: Elemental007
How exactly do the overhead lines transmit to the train?

There's a odd looking thing on top of the cars called a pantograph which rides against the underside of the electric wires over it and that's where the power is picked up.

 

[beer]

DART never got a damn thing right for the ten years I lived here. I go away for a year, come back, and there's light rail within like 5 miles of my house. It does seem pretty sucessful though. At least during rush hour, and compared to their busing.

 

[beer]

Originally posted by: kranky

Originally posted by: Elemental007
How exactly do the overhead lines transmit to the train?

There's a odd looking thing on top of the cars called a pantograph which rides against the underside of the electric wires over it and that's where the power is picked up.

Right, I see that. But how does the electricity get converted into useful work on the cars?

 

[ViRGE]

Originally posted by: Elemental007

Originally posted by: kranky

Originally posted by: Elemental007
How exactly do the overhead lines transmit to the train?

There's a odd looking thing on top of the cars called a pantograph which rides against the underside of the electric wires over it and that's where the power is picked up.

Right, I see that. But how does the electricity get converted into useful work on the cars?

Just like any other method involving electricity; it's pumped in to an electric motor which drives the car.

 

[beer]

Originally posted by: ViRGE

Originally posted by: Elemental007

Originally posted by: kranky

Originally posted by: Elemental007
How exactly do the overhead lines transmit to the train?

There's a odd looking thing on top of the cars called a pantograph which rides against the underside of the electric wires over it and that's where the power is picked up.

Right, I see that. But how does the electricity get converted into useful work on the cars?

Just like any other method involving electricity; it's pumped in to an electric motor which drives the car.

Well I knew that. I'm an EE, I was looking for more detailed specs. Namely, typical input voltage and current, motor efficiency, common top speeds, etc.

 

[KenGr]

Well, duh.. why don't you try www.lightrail.com

Most systems use DC power for the drive motors - ranging from about 400 volts to almost 1000 volts. Top speeds of cars range for about 50 to 75 mph.

 

[beer]

Originally posted by: KenGr
Well, duh.. why don't you try www.lightrail.com

Most systems use DC power for the drive motors - ranging from about 400 volts to almost 1000 volts. Top speeds of cars range for about 50 to 75 mph.

wow....just wow...now I feel like an idiot. Damn you Google.

 

[igowerf]

Originally posted by: Elemental007

Originally posted by: KenGr
Well, duh.. why don't you try www.lightrail.com

Most systems use DC power for the drive motors - ranging from about 400 volts to almost 1000 volts. Top speeds of cars range for about 50 to 75 mph.

wow....just wow...now I feel like an idiot. Damn you Google.

Perhaps you should start using Turbo10.com.