The Anonymous Widower

How Long Will A Class 345 Train Take To Go Between Two Stations Ten Kilometres Apart?

A Class 345 train has the following characteristics.

  • Maximum speed of 145 kph.
  • Acceleration of 1 m per second²

Using Omni’s Acceleration Calculator, I can calculate that, the train can accelerate up to full speed in 40 seconds.

Using the formula v²=u²+2as, this means that the train takes around 811 metres to get to 145 kph.

With regenerative braking, I suspect that a deceleration of the same order can be assumed.

So will it take 811 metres to stop from speed? I’ll use this figure until someone corrects me.

If the train is doing a start-stop over ten kilometres, then it will travel 8.4 kilometres at maximum speed, which will take about 3.5 minutes.

This means that the start-stop time will be 4.7 minutes.

Now I’ll look at a real example using a similar Greater Anglia Class 720 train.

These are 160 kph trains and typically work on the Great Eastern and West Anglia Main Lines with a similar operating speed.

The train will take 44.4 seconds to accelerate to operating speed and this will take 985.7 metres.

The distance between Tottenham Hale and Cheshunt stations is 12894.8 metres.

So the full speed distance could be 10923.4 metres. This will take 4.09 minutes at 160 kph.

So the start-stop time will be 5.5 minutes.

Currently, the fastest train on this route I can find takes 10 minutes.

I suspect that somewhere in this, the time at the station will complicate matters, but I do think that the fast acceleration and deceleration of the new trains will contribute to faster schedules.

And it’s not just Aventras that have this fast acceleration!

This is an extract for the Wikipedia entry for a Stadler Flirt.

Acceleration also varies between 0.8 and 1.2 m/s2 (2.6 and 3.9 ft/s2)

If you’re worried about the G forces, this is taken from the Wikipedia entry for London Underground’s 2009 Stock for the Victoria Line.

 They have a higher top speed of 80 km/h (50 mph), a faster maximum acceleration of 1.3 m/s2(4.3 ft/s2), a normal service deceleration of 1.14 m/s2 (3.7 ft/s2), and an emergency brake deceleration of 1.4 m/s2 (4.6 ft/s2).

These accelerate even faster and are used for over 200.000 million journeys a year.

To put in an example from motoring, a Mini Cooper S has a 0-60 mph time of 7.4 seconds, which is an acceleration of 3.62 m/s2

Conclusions

Possibly the most important thing to reduce journey times on a rail journey, is to make sure that the operating speed is as high as possible and trains running on the route must be capable of running at that speed.

Obviously, trains do the short journey in three sections.

  • They accelerate as fast as they can to the operating speed.
  • They cruise at the line speed.
  • They decelerate and brake, so they stop in the right place in the next station.

Dear Old Vicky has been doing this under computer control since, the line opened in the 1960s.

I gave an example from Merseyrail in Slow Trains Outside The South-East.

I said this.

The new Stadler Flirt trains are promised to save nine minutes between Southport and Hunts Cross stations, because they are better designed for passenger entrance and exit with faster speed and better braking and acceleration.

There is a corollary to all this.

So long as you have the energy on a train for fast acceleration, whether it is battery, diesel, electrification or hydrogen, it doesn’t matter for a faster service.

So alternatives to electrification are just as good!

 

August 23, 2018 Posted by | Transport | , , , , | 1 Comment

DB Says Innovative Freight Train Project ‘Very Promising’ So Far

The title of this post is the same as that of this article in Global Rail News.

This is the first paragraph.

A project to design innovative freight wagons, which is being financed by Germany’s Federal Ministry of Transport and Digital Infrastructure (BMVI), DB Cargo and VTG, is producing ‘very promising’ results.

The article is worth reading in full and in my mind it could be important in the development of efficient and reliable freight trains.

I remember in the 1960s, British Rail were trying to run faster freight trains and a lot of four-wheel wagons kept derailing.

Research at Derby using computer simulation solved the problem and went on to lead to a greater understanding of the dynamics of steel wheel on steel rail.

I do know that British Rail Research had one of the best tools for this job; a PACE 231-R analogue computer.

 

This is the one, that I worked on at ICI.

They were a powerful computer, which were capable of solving a hundred simultaneous differential equations.

They were late 1950s technology, based mainly on electronic valves, that responded to tender loving care.

But two of them working together, did the dynamic calculations for the moon landings, when linked to the digital computers of an Apollo capsule and lander.

On Apollo 13, when Jack Swigert said “Houston we have problem”, it was these machines, that were used to find a way to bring everyone home.

And the rest, as they say is history!

In my view, after over fifty years in computing, the rescue of Apollo 13 was the greatest piece of computing ever done with an electronic machine.

I’d love to know, whether the superb dynamics of the Mark 3 coach, are down to the work that was done on British Rail’s PACE 231-R

The second paragraph of the Global Rail News article has this phrase.

feature new digital systems which optimise handling.

Does this mean the Germans are worried about the handling?

I do sometimes wonder, if dynamic systems are best analysed using analogue computers and the demise of the technology means the same problems keep returning in different guises.

There can’t be many of us left, who’ve used an analogue computer seriously.

August 19, 2018 Posted by | Computing, Transport | , , , | 2 Comments