The Anonymous Widower

The Importance Of Speed On A Railway

I have just looked at the suburban services out of Waterloo and written Increasing Capacity On Waterloo Suburban Services.

In the Conclusion of that post I said this.

This calculation shows that you can sometimes replace a large number of 75 mph trains with a significantly smaller number of 100 mph units and still attain the same service frequency.

Effectively, the faster journey time, enables the train to go out and back on a route in a shorter time, which means that to do a given service frequency.you need less trains.

If a service takes 35 minutes with eight stops in a 75 mph Class 156 train, this would mean to go out and back would take around 90 minutes, if it took 10 minutes for the driver to change ends.

So the 07:00 train, would be back at the start to run the 08:30 service.

To run two trains per hour (tph) would require three trains, starting their diagrams at 07:00, )7:30 and 08:00.

Suppose the 75 mph train is replaced by a faster modern 100 mph train, that can perform very quick stops at a station, due to powerful brakes and strong acceleration, which can save a minute at each stop.

The faster train might be able to do the complete out and back journey in under an hour, which would mean only two trains could run the same 2 tph service.

This would give the following benefits.

  • Passengers wold get a faster journey.
  • The operator would need one train less to run the same service.

There are also several smaller benefits to the operator, like less crew and smaller depots.

Since the turn of the century, increasingly, there has been efforts to squeeze more and more services onto rail lines.

In the following sections, I’ll discuss how various factors affect capacity.

Faster Trains

On a simple out-and-back route, the faster a train can get to the destination and back again, the better.

  • In the 1980s, suburban trains like a Class 455 train had a speed of 75 mph.
  • In the 2000s,  a train like a Class 377 train have a speed of 100 mph.
  • In the 2010s,  a modern train like a Class 387 train have a speed of 110 mph.

Trains are certainly getting faster.

Trains Stop Quickly At A Station

Train manufacturers are spending a lot of time, shaving seconds off the time it takes a train to do the following.

  • Brake from line speed.
  • Stop precisely in the station.
  • Drop off and board any passengers.
  • Accelerate back to line speed.

Techniques employed include.

  • Better brakes
  • Wide lobbies and doors
  • Fast door-opening systems.
  • Step-free train access
  • Fast acceleration.
  • Automation and better systems.
  • Staff on the platform from first to last train.

In the next few years, stops will get even quicker.

  • Regenerative braking using batteries to store energy on the train for a fast getaway, will also cut energy use.
  • CCTV systems for door opening and closing on the train, rather than the platform.
  • Automatic stopping of the train at the correct place, after the driver presses a stop button perhaps two hundred metres from the station.
  • Automatic acceleration of the train back to line speed.

Victoria Line trains have been using the last two since 1967.

Modelling And Analysis

We’ll also be seeing a lot more Modelling of systems and analysis of performance, to find how perhaps small amounts of investment can provide a better service.

Conclusion

Trains are going to get faster.

 

April 20, 2017 - Posted by | Travel |

1 Comment »

  1. Eh? The Class 317s, which the 455s are derived off, can do 100mph. And the Class 387s (certainly not until they start operating the faster GWR services) don’t reach 110mph in service.

    And you do realise that adding heavy batteries is somewhat counter-intuitive, right? And widespread ATO is going to take many decades to achieve. So certainly not “in the next few years”.

    Comment by David | April 21, 2017 | Reply


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