Jo-Jo vs


More about Jo-Jo train versus other trains will in time apear here.

Jo-Jo train versus other trains


1. Travel time

2. A comparison between maglev trains and Jo-Jo trains

3. If there were...

1. Travel time

Travel time is the time from your start point to your destination. It consists of the sum of several times:

  1. If you have a long way to the station, it can take a lot of time to get there.
  2. If the trains seldom run, you have to plan and maybe leave earlier than you intended.
  3. So we have the time between departure and final station.
  4. Finally, the journey from the terminus to your destination is added.

With the Jo-Jo concept, we have many stations located near the travel center or where there are plenty of parking spaces. This makes the time 1st and 4th short. High frequency makes the time 2. short. Direct travel at high speed makes time 3. short. The Jo-Jo option is often unbeatable.

2. A comparison between maglev trains and Jo-Jo trains

With a docking train, it takes 245 km/h about 1 hour and 50 minutes to get from place A to place B, 450 km, type Sthlm - Gtbg. This applies largely regardless of the number of stations on the route in between. And then passengers and freight cars are left and picked up to / from the docking train to/from each passenger station and freight terminal.

In Shanghai, there is today the only commercial maglev train. It goes with a maximum of 431 km/h in high traffic and then it is shaky and uncomfortable. With 300 km/h in low traffic, it is comfortable. In discussions, it is stated that maglev trains can run at 500 km/h and that speed has been well reached in experiments, but is not something that anyone in the near future plans for.

Someone writes (comment in Ny Teknik 2019-08-27) that with 500 km/h, 450 km distance and 10 intermediate stops, the maglev train can complete the journey in 90 minutes. 20 minutes faster than the Jo-Jo train which has a maximum speed of 250 km/h. But is that really correct?

Let's make a simple estimate.

With 1 m/s2 as the highest acceleration/deceleration, passengers can helpfully move in the train. Increasing the speed from zero to 500 km/h then takes 139 seconds. Equally long time to slow down. With 10 intermediate stops, it then takes 139 x 2 x 11/60 = 51 minutes. The distance that the train travels during this time is (500/2) x 51/60 = 212 km. The remaining 450 km of the distance will thus be 238 km. At 500 km/h, it takes 28.5 minutes to drive that distance. In total, we have now spent quite exactly 90 minutes. But at the stations, passengers must have time to get off or get on the train, otherwise there is no reason to stay at the station. It usually takes 3 to 5 minutes. Always assume fast passengers, then it takes 3 minutes per station. The total travel time Sthlm - Gtbg, with 10 intermediate stations, with the maglev train is thus 120 minutes or two hours, that is 10 minutes slower than the Jo-Jo train. So the comment made in Ny Teknik was not correct!

More intermediate stops increase the total time for the maglev train, but do not affect the travel time of the Jo-Jo train. Note that the Jo-Jo train can also carry freight cars.

As a small exercise, we can imagine that the maglev train can accelerate/brake three times as fast. Then the 51 minutes shrink to 17 minutes. However, passengers must then during this time be strapped to their seats. Boarding and disembarking takes significantly more time, e.g. 6 minutes per station, ie a total of 60 minutes. The braking and acceleration distances will be shorter and the distance with 500 km/h will be about 379 km, which with 500 km/h takes just over 45 minutes. The sum is thus 17 + 60 + 45 = 122 minutes, ie a little over 2 hours. So no point in increasing the acceleration. It just gets more inconvenient and costs more energy and requires more expensive trains and tracks.

Who wants to be strapped into the seat of the train. Who wants to be frequently subjected to heavy braking and acceleration, respectively. Speed ​​changes consume a lot of energy and high speeds specifically. High speed requires straight paths. Building on pillars over the existing motorway for the Jo-Jo train is by far more cost-effective. Another clear advantage of the docking train is that it can be put into operation in short stages, which is not possible with either maglev trains or more traditional high-speed trains.

No, the Maglev train without static switches is probably good for long direct journeys between large metropolises. The Jo-Jo train is superior for travel in Sweden. Let the whole country live!

Text in preparation

3. If there were...

Maglev trains use wheels only at low speeds and if the levitation system is otherwise shut down, the train floats freely in the air without mechanical contact with the ground. It's great. The rolling resistance is eliminated.

For a classic railway vehicle, iron wheels against iron rails and ball bearings against wheel axles apply. If it was judged that the ball bearing's friction losses are significant, it could theoretically be exchanged for a maglev bearing. A technique that, like the maglev train, uses the property that magnetic opposite poles shun each other.

Iron wheels against the rails have low rolling resistance, low adhesion. In the classic train, the locomotive has a high weight and can thus pull the following carriages. With motor vehicle trains (all vehicles in the train have their own drive), the high weight is not required, but the motor vehicle cost is higher than just the rolling carriage.

Train development today seems to be moving towards more motor vehicle trains. Heavy locomotives place great demands on the track. Acceleration and deceleration can be done faster with motor train trains.

If we have ERTMSL3 (European Rail Traffic Management System Level 3), we do not need to have the rails divided into fixed block sections. I and S rails used to know if there is a train on the block section are not needed. Then we could use the AC brake for faster deceleration of the train. This type of brake works without direct contact with the rails, but can not be used today as it disturbs the I and S system.

If there was a static gear also for maglev trains then we could use it in the Jo-Jo concept. With 500 km/h, the travel time would be halved. Stockholm - Malmö in 1 hour 15 minutes, Stockholm - Gothenburg less than an hour.

Topics to be handled, described.

  • Frequency
  • Many stations
  • Low cost
  • Quickly ready
  • Economy - compare with Highspeed train

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