Equipment order expected in January

[jis]

My fearless prediction is that third rail will not be used for any mainline electrification in this day and age. Every town on the route will throw a veritable hissyfit about the danger of people getting electrocuted etc., which of course would be in addition to the fact that third rail electrification in all likelihood will end up costing more than OHE anyway for long distance electrification.

 

[wrjensen]

I found the answer in "when the steam railroad electrified" (great book by the way)

The main line from New Haven to Hartford was not electrified but lines near Hartford were but not the line that Amtrak uses.

 

[George Harris]

this is just a thought but would it be cheaper to just use 3rd rail power then overhead. that way there's no clearance issues height wise.

That would solve the clearance issues, but it would not be cheaper to do. It would be more expensive, as 3rd rail power requires many more substations to provide power. Additionally, now you need to run out and buy equipment that can run on third rail power.

So again while it does solve one problem rather nicely, it creates a few others and therefore I wouldn't expect them to consider it. But who knows? Stranger things have happened.

Third rail power is usually limited to 1000 volts maximum. Most systems are either 600 or 750 volts.

At these low voltages a very large condutor rail is necessary to get much power across. The only extensive main line electrification that I know about (not counting Long Island RR or the ex NYC lines) is British Southern Region. Generally speed is limited to aobut 100 mph.

Also, third rail cannot be continuous through turnouts. There must be a gap to keep the third rail shoe from coming into the side of the third rail at the switch. For high speed turnouts this gap gets very long.

 

[delvyrails]

I found the answer in "when the steam railroad electrified" (great book by the way)
The main line from New Haven to Hartford was not electrified but lines near Hartford were but not the line that Amtrak uses.

New third rail electrification is just about obsolete for railroads. At the maximum of 600-750 volts, the required current for any kind of passenger train speed or heavy freight would require an uneconomic amount of feeder cable and too many substations. Short extensions of an existing third-rail network are probably the only exceptions.

Actually, there was a New Haven Railroad suburban third-rail electrification in existence at one time between Hartford and Waterbury.

 

[jis]

Interestingly many of the newly constructed Metro systems choose to use bigger diameter tunnels and deliver power to the trains via 25kV AC or at least several thousand volts DC OHE rather than third rail.

 

[George Harris]

Interestingly many of the newly constructed Metro systems choose to use bigger diameter tunnels and deliver power to the trains via 25kV AC or at least several thousand volts DC OHE rather than third rail.

Which ones and where?

There are some that use 1500VDC overhead. So far as I know 3000VDC is about as high as DC electrification has ever gone anywhere.

 

[jis]

Interestingly many of the newly constructed Metro systems choose to use bigger diameter tunnels and deliver power to the trains via 25kV AC or at least several thousand volts DC OHE rather than third rail.

Which ones and where?

There are some that use 1500VDC overhead. So far as I know 3000VDC is about as high as DC electrification has ever gone anywhere.

Two that immediately come to mind are Rome, which is 3kV DC AFAIR. Delhi is 25kV AC/50Hz. Of course all of the Paris RER lines are OHE DC electrified, except B, D north of Gare du Nord is 25kV and E is 25kV. I believe all new Metros in India will be 25kV. Only Calcutta will retain its current line using third rail DC electrification. Hong Kong MTR's newest line is OHE.

 

[George Harris]

Interestingly many of the newly constructed Metro systems choose to use bigger diameter tunnels and deliver power to the trains via 25kV AC or at least several thousand volts DC OHE rather than third rail.

Which ones and where?

There are some that use 1500VDC overhead. So far as I know 3000VDC is about as high as DC electrification has ever gone anywhere.

Two that immediately come to mind are Rome, which is 3kV DC AFAIR. Delhi is 25kV AC/50Hz. Of course all of the Paris RER lines are OHE DC electrified, except B, D north of Gare du Nord is 25kV and E is 25kV. I believe all new Metros in India will be 25kV. Only Calcutta will retain its current line using third rail DC electrification. Hong Kong MTR's newest line is OHE.

OK, I guess you could consider 3000V as "several thousand."

I think, but am not certain that Hong Kong MTR is 1500V DC. All of Hong Kong MTR is overhead electric and was so from the beginning. (I will be seeing a long time HK MTR man Monday and will correct the voltage if it is wrong)

Hong Kong KCR is 25 kv 50 cycle overhead, but it also hauls long distance trains as well. However, the 25 KV predated the electrification of the line on the Guangdong side of the border, so for quite a few years the long distance trains were diesel hauled.

The Paris RER services are more on the order of commuter rail than Metro.

 

[jis]

The Paris RER services are more on the order of commuter rail than Metro.

They bear an eerie resemblance to BART or WMATA, specially the RER A line. RER-C is clearly old suburban line converted to RER. RER-B is sort of like RER-A more than like RER-C. D and E are the newest lines and within the city they all are like subway, while outside they are like commuter service, but typically with much more frequent service than what is common in the US.