A few lines of the Paris Métro in France operate on a four-rail power scheme because they run on rubber tyres which run on a pair of narrow roadways made of steel and, in some places, concrete. Since the tyres do not conduct the return current, the two guide rails provided outside the running 'roadways' double up as conductor rails, so at least electrically it is a four-rail scheme. One of the guide rails is bonded to the return conventional running rails situated inside the roadway so a single polarity supply is required. The trains are designed to operate from either polarity of supply, because some lines use reversing loops at one end, causing the train to be reversed during every complete journey. The loop was originally provided to save the original steam locomotives having to 'run around' the rest of the train saving much time. Today, the driver does not have to change ends at termini provided with such a loop, but the time saving is not so significant as it takes almost as long to drive round the loop as it does to change ends. Many of the original loops have been lost as lines were extended.
Is there an answer to this question (If it cannot be answered, say "unanswerable"): All lines of the Paris Metro in France operate on what?
unanswerable
Ett fåtal linjer i Paris Métro i Frankrike drivs med fyrspåriga kraftsystem eftersom de körs på gummidäck som löper på ett par smala vägbanor av stål och på vissa ställen betong. Eftersom däcken inte leder returströmmen, fördubblas de två styrskenorna som finns utanför de löpande "vägbanorna" som ledarskenor, så åtminstone elektriskt är det ett fyrspårigt system. En av styrskenorna är bunden till de retur konventionella löpskenor som ligger innanför vägbanan så en enda polaritetsförsörjning krävs. Tågen är konstruerade för att fungera från endera av försörjningspolarna, eftersom vissa linjer använder backslingor i ena änden, vilket gör att tåget vänds under varje fullständig färd. Slingan tillhandahölls ursprungligen för att rädda de ursprungliga ångloken som måste 'köra runt' resten av tåget och spara mycket tid. Idag behöver föraren inte byta ändpunkter vid termini försedd med en sådan loop, men tidsbesparingen är inte så betydande som det tar nästan lika lång tid att köra runt loopen som det gör för att byta ände. Många av de ursprungliga looparna har gått förlorade i takt med att linjer förlängts. Finns det ett svar på denna fråga (om den inte kan besvaras, säg "osvarbar"): Alla linjer i Paris Metro i Frankrike opererar på vad?
A few lines in Paris Métro, France, are powered by four-track power systems because they run on rubber tyres running on a pair of narrow steel roadways and in some places concrete. Since the tyres do not lead the return current, the two steering rails located outside the running "roadways" as guide rails are doubled, so at least electrically it is a four-track system. One of the guide rails is tied to the return conventional running rails located inside the roadway so a single polarity supply is required. The trains are designed to operate from either of the supply coils, as some lines use back loops at one end, causing the train to turn during each full journey. The loop was originally provided to save the original steam locomotives that had to 'run around' the rest of the train and save a lot of time. Today, the driver does not need to change the end points at termini fitted with such a loop, but the time savings are not as significant as it takes almost as long to drive around the loop as it does to change the end. Many of the original loops have been lost as lines extended. Is there an answer to this question (if it cannot be answered, say "unanswerable"): All lines in Paris Metro, France, operate on what?
Osvarsbart
Unanswerable