I rode Amtrak from Groton, CT, to Portland, ME last night, which means changing trains in Boston. The southbound trains we passed were led by their locomotive, as was our northbound train. How are the trains turned in Boston?
On a side note - I'd never noticed that there was only one pantograph on the train before. How is the circuit completed? Through the track? Doesn't that make the rail live, at least between the train and whereever the circuit is completed?
Sorry, I can't answer how they turn trains. I would have to assume that if they actually TURN trains they would need to pull the train out to some place where they'd have a wye or loop track. I hope loop track is self explanatory, in case you have trouble visualizing a wye track, look at the diagram http://www.answers.com/topic/wye-railroad.
As for electricity, think of electricity as a fluid, just like water. If you had a river with a pump to a pipe which ran 50 ft upstream, the water would fall out of the upstream end of the pipe, go back into the river, and flow downstream back towards the pump. Even if you put your foot into the river, the water would not flow up your body, into your nose and lungs and drown you. Instead it would continue flowing downstream, and some of it would go back into the pump and back into the pipe, and repeat the circuit.
Likewise, the electricity flows out of the wire, into the pantograph, through the motors, trucks and wheels, into the tracks. Even if you put your foot on the track the electricity will not flow up your body and stop your heart. Instead it continues flowing through the track and back to the power plant to repeat the circuit.
Just as with the water, where we have to introduce some new energy into the equation at the pump, we also have to introduce some new energy at the power plant in order to keep the circuit going. It's not going to flow back up the pipe, or back through the wires, by itself, but neither will it flow if there's anything that interrupts the circuit.
By the way, the fact that there's only 1 pantograph on the train does not have anything to do with the circuit. Even if there were more than 1 pantograph, since there's only 1 wire the other half of the circuit is still through the tracks. In order to have a second pantograph contribute to the other half of the circuit you'd need to have 2 wires, and then if the second pantograph stayed on the second wire then the second wire could perform the electrical duties that the track now performs.
Since the railroad has track anyway we usually use only 1 wire. The only rail installations I know of which used a second wire were Cincinatti and Havana Cuba street cars, and I believe the reason was because they were really sloppy about maintaining proper electrical bonds between track sections, so there was electrical leakage. Keeping with the water analogy, imagine if the water had an incredibly swampy shoreline, so it kept flooding the surrounding countryside between where the pump was and where the pipe emtied.
Patrick Boylan
Free yacht rides, 27' sailboat, zip code 19114 Delaware River, get great Delair bridge photos from the river. Send me a private message
The LARGE, former New Haven, Northampton Street Yard and Service Shops, are next to and southeast of South Station.
Amtrak (all electric in Boston) pulls the inbound Regionals out to the yard for service and to switch the locomotive. They then back the train into the platforms to load and return South (west in New Haven terms). Acela trains have locomotives on both ends, no problem.
MBTA always has the locomotive "outbound" and use "control cab cars" in push mode to return to the Station. This keeps the diesel smoke out of the Stations.
Don U. TCA 73-5735
You say they keep the locomotive on the out of station end to reduce smoke. Well I guess this kind of answers a question I've had, does MBTA have any electric trains, now that Boston-Providence is electrified. And by extension, does Connecticut New Haven east to wherever (New London is it?) run diesel or electric?
If not electric now, do they, Boston-Providence, or New Haven east have any plans to run electric commuter trains? Hasn't the wire been up since late 2000, 8 years now?
Electricity requires a complete circuit to flow. The cantanary is one side of the circuit and the track is the other.
You can stand safely on the track. You can hang safely from the overhead wire. That's why birds and squirrels don't get electrocuted on the wire.
If you touch both the track and the wire at the same time, you will complete the circuit, just like the train does, and you will turn to charcoal in a puff of blue smoke.
Dave
Lackawanna Route of the Phoebe Snow
gardendance wrote: You say they keep the locomotive on the out of station end to reduce smoke. Well I guess this kind of answers a question I've had, does MBTA have any electric trains, now that Boston-Providence is electrified. And by extension, does Connecticut New Haven east to wherever (New London is it?) run diesel or electric?If not electric now, do they, Boston-Providence, or New Haven east have any plans to run electric commuter trains? Hasn't the wire been up since late 2000, 8 years now?
The MBTA Boston-Providence service is still diesel-powered and CDOT's Shore Line East service is also diesel-powered. Electric service on Boston-Providence would be counter-productive since MU cars or electric locomotives would be tied to that line to the exclusion of the rest of the MBTA network.
CSSHEGEWISCH wrote: Electric service on Boston-Providence would be counter-productive since MU cars or electric locomotives would be tied to that line to the exclusion of the rest of the MBTA network.
Electric service on Boston-Providence would be counter-productive since MU cars or electric locomotives would be tied to that line to the exclusion of the rest of the MBTA network.
Is that the kind of thinking that made this nation great? Let's put up wires on the rest of the MBTA network!
gardendance wrote: CSSHEGEWISCH wrote: Electric service on Boston-Providence would be counter-productive since MU cars or electric locomotives would be tied to that line to the exclusion of the rest of the MBTA network.Is that the kind of thinking that made this nation great? Let's put up wires on the rest of the MBTA network!
Show me the MONEY!!!
As for smoke, the Boston Bus Terminal is built over the tracks at South Station. When it opened, it was filled with diesel smoke. Now the MBTA Diesel road engines are down the track, away from the station and Bus Terminal. Amtrak is all electric except for yard switching.
Just guessing--
As for Electric locomotives, only The Corridor is under wire. That's only 88 miles (44 miles double tracked to Providence) of the 600 miles in MBTA service. Three single track, non-electrified, diesel powered, branch lines come off The Corridor to Newton, Franklin, and Stoughton. MBTA lists 80 Diesel Locomotives, ether F40PH or GP40-MC, an electric locomotive could only be used on that one line.
In Connecticut, CONNDOT's "Shore Line East" from New Haven to Saybrook and New London is Diesel hauled coaches, a few trips a day. Few high platforms alone that line so MU cars are out. Remember, Amtrak hauls "Interstate Passengers", no commuters.
This is a good explanation. The reason trolley buses like those in San Francisco need two wires is because there is no rail.
Our community is FREE to join. To participate you must either login or register for an account.