49 replies to this topic

[Snowguy716]

You can create a third rail system that is wedged underneath a lip on the rail underneath the street, so basically hte only way to get electrocuted by it would be to wedge your hand or something inside the rail and grab around for it... in which case, the consequences are obviously deserved

Most heavy rail outside of cities has overhead wires.  It is mostly just subways that have the 3rd rail.

[lammius]

Yeah I don't think the electrification generalization (LRT = overhead / HRT = 3rd rail) is a good one to make.  All of AMTRAK's regional rail on the Northeast Corridor and I believe most of the rest of their network run on overhead electric wires.  Furthermore, both LRT and HRT often run with diesel (DMU/RDC) or dual-mode diesel/electric.  

The RiverLINE LRT in southern New Jersey is the first low-floor articulated DMU (Diesel Multiple Unit) to operate in the US.

Edited by lammius, 31 January 2007 - 05:30 PM.

[Cotuit]

lammius, on Jan 31 2007, 06:29 PM, said:

Yeah I don't think the electrification generalization (LRT = overhead / HRT = 3rd rail) is a good one to make.  All of AMTRAK's regional rail on the Northeast Corridor and I believe most of the rest of their network run on overhead electric wires.  Furthermore, both LRT and HRT often run with diesel (DMU/RDC) or dual-mode diesel/electric.

Also, Boston's blue line which is heavy rail has both 3rd rail and overhead wires. In the subway portion it's third rail, on the surface sections it's overhead. It makes the switch just before Airport Station.

[tampasteve]

lammius, on Jan 31 2007, 06:29 PM, said:

All of AMTRAK's regional rail on the Northeast Corridor and I believe most of the rest of their network run on overhead electric wires.

Great Pic of that car! Although, I could be reading into the post....but almost all of Amtrak's operations are with Diesel train sets; I believe that only the ones in the NE are wired.

Steve

[dtown]

Yeah, im quite sure its only the NE Acela line that is overhead electric.

[Jayayess1190]

Amtrak's overhead electric operations are from Boston, Mass to Washington D.C. and from Philadelphia, PA to Harrisburg, PA.

[Snowguy716]

I remember seeing a few diesel trains running in Austria that served rural routes where electrification was just not worth the cost.  It was always so weird to see them leave the station, because they belched out a bunch of smoke as they left and didn't get nearly the acceleration that electrified rail got.  Also, they were much louder.

[dougmatic]

Won't light rail subways really not be much more cost efficient than heavy rail subways? I always thought that the tunneling costs were a lot greater than the cost of the actual cars. Therefore, light rail subways would save some cost because light rail is cheaper than heavy rail, but the tunneling costs are still there. I'm not saying that it's not cheaper because it is, but not that much cheaper because the majority of the costs are in tunneling.

[Cotuit]

dougmatic, on Oct 20 2007, 03:22 PM, said:

Won't light rail subways really not be much more cost efficient than heavy rail subways? I always thought that the tunneling costs were a lot greater than the cost of the actual cars. Therefore, light rail subways would save some cost because light rail is cheaper than heavy rail, but the tunneling costs are still there. I'm not saying that it's not cheaper because it is, but not that much cheaper because the majority of the costs are in tunneling.

Using light rail gives you greater flexibility. You can be grade separated where you need to be, but run in the street or have at-grade crossings wherever you like. Boston, Philly, and SF for example have street cars in the less congested outer neighborhoods that go underground in the more congested center city. If those systems were heavy rail, they'd need to be entirely grade separated either underground, or in a ditch, or elevated... That's where you save money, only need to separate the grade where it really needs it.

[cloudship]

Tunneling costs are also quite variable. True that they are expensive, but a cut and cover situation is a lot cheaper than a bore. But in either case, whether you have to dig a tunnel or need no tunnel, the costs aren't radically different between light rail and metro. Of course it also depends upon the size tunnel you need.

The ultimate factor in many cases, however, is really load factors. Light rail simply can handle lighter loads more efficiently. Metros cost more upfront, but can deal with much larger volumes. The size and weight of the railcars makes a huge difference in operating costs and energy use, but if you are carrying heavy loads, it may be more efficient to go with a heavy rail solution.