[ih] Speaking of layering and gateways

[Brian E Carpenter]

On 16-Apr-24 10:43, Bob Hinden via Internet-history wrote:
> John,
> 
> Very nice article!
> 
> I have taken a train  Hamburg to Copenhagen in the early 1980s.    The train cars went onto a ferry from Rødby Sogn to Puttgarden.    The networking analogy is, of course, encapsulation.
> 
> Bob
> 
> p.s. I see this is no longer running, the current route is a mix of land and bridges.

Cars and trucks are encapsulated in a train for the Channel Tunnel between England and France. Alternatively, they are encapsulated in boats. Both systems are exposed to head-of-line blocking, are best effort, and implement collision avoidance.

    Brian

> 
> 
> 
> 
> 
>> On Apr 15, 2024, at 11:28 AM, John Levine via Internet-history <internet-history at elists.isoc.org> wrote:
>>
>> Back in the 19th century there were a lot of railroads built in a lot
>> of incompatible ways. The most obvious incompatibility was track gauge
>> but there were others including the couplers between the cars and the
>> ways they did (or sometimes did not) ensure that there was only one
>> train at a time on each piece of track.
>>
>> These days most of the world has converged on standard gauge but there
>> are still places like Spain and Russia that use broader gauges, and
>> mountain railways and trams that use narrower. When a passenger or
>> freight train crosses a border there's a variety of approaches, some
>> of which may seems kind of familiar.
>>
>> The conceptually simplest approach is a gateway, at the border
>> everyone gets off one train and gets on another.  The Canfranc
>> station in the Pyrenees at the France-Spain border was famous
>> for this.
>>
>> https://en.wikipedia.org/wiki/Canfranc_International_railway_station
>>
>> Another approach is layering. At the border, equipment lifts the car
>> bodies off the bogies of the old gauge and puts them onto bogies of
>> the new gauge. This is better since passengers don't have to get out
>> (often from sleepers in the middle of the night) and goods don't have
>> to be unloaded. This technique was patented in 1876.
>>
>> Here's the Prague-Moscow train changing gauge in Brest, Belarus.
>>
>> https://youtu.be/2nI467sc-Eo?si=w783HVwUGXAmQD7_
>>
>> Yet another approach is parallel operation, dual or triple gauge, with
>> three or more rails allowing trains of different gauge to run on the
>> same route. In Japan the Shinkansen are standard gauge but older
>> railways are mostly 1067mm so there's a fair amount of dual gauge in
>> and out of cities.
>>
>> This is a very old solution. The Niagara Falls bridge in 1855 had four
>> rails for three different gauges, although now it's down to two.
>>
>> Here's a video of a dual gauge Shinkansen route:
>>
>> https://youtu.be/0d0XAaqEZ0s?si=ZYo27gNoAAXibtVq
>>
>> Another approach is switching on the fly. Some trains have variable
>> bogies that can change gauge as the train is moving, which is pretty
>> cool.
>>
>> Here is a Swiss train doing that:
>>
>> https://youtu.be/H0gj2LWe-SI?si=7zpZFc-jQPTIv8TX
>>
>> And a tutorial in Spanish:
>>
>> https://youtu.be/y8N7Ikw87tM?si=bCwrx5ph3SpgrevM
>>
>> The last approach is a flag day. One of the reasons the south lost the
>> US Civil War was that they had a fragmented rail network, which
>> continued to inhibit recovery and development after the war. So over
>> two days, May 31-Jun 1, 1886, southern railroads regauged 11,500 miles
>> of track to the Pennsylvania's gauge (1/2" wider than standard but
>> close enough) and changed the bogies on the rolling stock.
>>
>> Here's a video about it:
>>
>> https://youtu.be/4v81Gwu6BTE?si=Yi9JDSU0onABpWju
>>
>> R's,
>> John
>> -- 
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>> Internet-history at elists.isoc.org
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>