sspid14 wrote:Example: I go to my grandmother's house 50 minutes from here by car or train at 1:20 from here. If I take the train, my weight will not influence the consumption of the train and if I take the car, I will consume petrol. So with or without me, the train will have consumed, but I can choose to consume (or not) with the car.
Exact but I can give you a counter example: we can do almost the same reasoning with the plane ... I say almost because the consumption of an airplane will be very slightly higher with one more passenger ... (that of a train too, physically speaking, but much more negligible I think)
sspid14 wrote:What about consumption for the transport of goods from elsewhere ??
And the road truck rail transport .. interesting ??
A priori it is not too much (too expensive, too many constraints for truckers ...) otherwise we would see a lot more.
Piggybacking has become a False Good Idea in the current economic context: slower and more expensive than the truck alone, so nobody uses ...
Transport by train is reserved for heavy goods in large quantities and generally far from the final consumer (minerals, cereals ...).
I think I have never seen a refrigerated wagon in real life !! Who has seen it before?
On the other hand, river transport is in full swing! The autonomous ports of Strasbourg and Liège are rediscovering their second youth at the moment!
Proof that the river knew how to adapt much better to the economic context than the train!
By the ton.km transported the river is much cleaner than the train.
stipe wrote:Yesterday! The TGV has been doing this for a very long time (at least for 10 years)
Uh I thought that all the TGV models were equipped ... to be checked ..
Well, I found this very complete article on braking trains:
http://florent.brisou.pagesperso-orange ... rganes.htmwhich against says all that I thought, on the recovery by re-injection network, in bold the essential ...
The electrodynamic brake
When a generator delivers on a load (resistance for example), a resistant force appears on its shaft tending to slow it down. This is true regardless of the type of generator: direct current, synchronous or asynchronous. Only the methods to initiate and maintain the process differ.
It is therefore quite natural that an electric traction motor, whatever it is, can be used as a generator so as to produce a braking force which will slow down the origin of its movement, that is to say the axle to which it is mechanically coupled by the transmission.
Thus was born the electrodynamic brake, which covers:
* the rheostatic brake: the traction motors flow in rheostats on board the machine, which then dissipate the energy in calorific form in the atmosphere
* the regenerative brake: the traction motors supply the high-voltage power line, the energy thus restored can be reused by the other convoys, or sent back to the supply network through the substations.
The first type of brake has the advantage of being able to be implemented independently of any high voltage power supply, therefore in particular on a diesel-electric locomotive. On the other hand, the braking energy is dissipated in pure loss.
The second type of brake has the advantage of being able to recover braking energy, and therefore very significantly improve the economic performance of vehicle operations. However, it requires:
* the installation on board the machine of reversible and efficient power supply equipment, so as to be able to return a current of characteristics close to that supplied by the substations to the supply line, this is that is to say little "polluted" by harmonics.
* the presence of consumers at the same time on the supply line, as electrical energy cannot by definition be stored. This type of brake cannot therefore operate during off-peak hours (first and last trains), or else requires reversible substations (therefore a little more expensive) to return the energy to the distributor (EDF in France). This last aspect is hardly ever implemented, taking into account the constraints of "purity" of the returned current imposed by the distributors of electrical energy.
This is why the rheostatic brake is mainly used on main line equipment (locomotives, TGV), which brake infrequently and whose mechanical brake is sized to be able to operate on its own temporarily without overheating or excessive wear, while the regenerative brake equips rather urban materials (trams, metros) and suburban materials (railcars). Note that some equipment (trams in particular) is equipped with two types of brake, especially when the mechanical brake remains relatively undersized thermally due to constraints in terms of volume available on the bogies.
The dynamic brake has another advantage: with a suitable design of the power equipment and their control electronics, the dynamic brake can be considered safe, and therefore it can be taken into account while respecting braking performance with regard to signaling. Without this aspect, the TGV would certainly not have seen the light of day, since the dynamic brake makes it possible to compensate for the fact that the reduced number of bogies (articulated architecture of the train) and the reduced space available on the motor bogies does not allow install a large mechanical braking capacity.
Finally, it should be noted that certain specific constraints, independent of the rolling stock, can greatly influence the choice of the type of electrodynamic brake. Thus, in France, if recovery is possible everywhere with a 1,5 kV continuous supply (subject to regulatory constraints), on the other hand, it is difficult with a 25 kV single-phase supply. Indeed, SNCF supplies its network from the closest EDF network, but two adjacent substations are not necessarily connected to the same (three-phase) EDF supply phase, for consumption balancing issues. This is why the SNCF lines supplied with 25 kV single-phase are equipped, between the substations, with disconnections intended to prevent short-circuits due to phase difference between the substations. The probability that two trains are on the same section of about fifty kilometers being low, and the substations are most of the time not reversible (to avoid sending back to the EDF network a voltage that is not "pure "), It is clear that regenerative braking is not interesting because it is not very available. Only suburban lines supplied with single-phase can have an attractive recovery rate, even justifying the absence of associated rheostatic braking (case of Z 20500). In Germany, on the other hand, the DB supplies all of its lines from a single network, without phase shift. There is therefore no systematic sectioning, which almost certainly guarantees the presence of a train (and therefore of a consumer) in a relatively close radius. DB equipment is almost never equipped with dynamic braking.
Like what the "legends" die hard ... and the type of network / current used matters enormously in the reinjection and EdF has very probably not pushed for these reinjections ... unlike the German electricity operators ...
stipe wrote:Wow! "several deaths" !!! lol Fortunately, on this side we do not compare with the car.
http://fr.wikipedia.org/wiki/Accident_f ... %27Eschede101 dead all the same ... it doesn't make me laugh ...
There was no question of comparing to cars but of saying that the maintenance cost was not zero and that if we reduced it could lead to this kind of disaster ...
Then, road deaths are due in the vast majority of cases to a human and not technical defect! This is not the same...
On June 3, 1998 the tire of an ICE 1 wheel connecting Munich to Hamburg broke next to Eschede [1]. The train breaks up on a bridge pile, killing 101 and injuring a hundred (out of a total of 287 people on the train): it is the worst train accident in German history since 1971, and the worst high speed train accident in the world.
All this because preventive maintenance (ultrasound or eddy current) to detect a fatigue defect in this wheel has no longer been done !!
stipe wrote:Because it must be remembered, the train in France is still the best way to arrive alive at your destination.
No it's the plane ...
