Ark II
Here's a guess:
Ark II Three young scientists travel around the country in the 25th century after the world has been ravaged by pollution.
In their hi-tech RV, the titular Ark II, they study the land and help out those in need.
Go here and here for more details, episode guides and pics.
Watch a making-of documentary here .
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Yet another possibility:
This is the Overlander from Terrahawks .
It's function is: an automated all-terrain vehicle similar to a rail-free train with multiple, articulated sections that brings supplies to Hawknest.
- ( Wikipedia )
This image is from David Sisson's page - a man who restored the original model.
In your question, you mention multiple sections , which the Overlander had.
And you mention mountainous terrain - which was exactly the terrain on which the Overlander drove.
See if the vehicle in this video looks familiar:
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This is almost certainly The Highwayman .
It was another cheesy Glen Larson series from the late 1980s or so, and depicted two quasi-law enforcement officers who drove trailer trucks that
(I kid you not) could convert into helicopters.
One of them had this ridiculous Australian accent, but I am uncertain if this was just acting or if he was someone famous from that continent or whatever.
I don't think it lasted a full season.
Here is an image I dug up on Google to confirm it:
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Could you be thinking of Damnation Alley ?
Although produced and released as a theatrical movie, it made its way to TV fairly quickly.
IIRC, the TV version was broadcast in two parts, making it feel like a mini-series.
Practically another star of the show, the "Landmaster" was a custom-built articulated vehicle with a very unique wheel arrangement - the three-wheel clusters could rotate to climb over large obstacles.
The Landmaster was actually built full-scale and driveable, having a working drivetrain.
As for the "specialized sections", could you be thinking of the movie The Core ?
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Sounds like Genesis II and/or Planet Earth .
These Gene Roddenberry TV movies involved a train system and the character name Dylan Hunt.
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I think you might have a few shows mixed up
but I believe I have your answer.
I believe that you are referring to the second season of The Highwayman where they added the actor Mark Alexander "Jacko" Jackson who was a former Australian rules football player.
He had a different-styled (1/2-height) tractor that could separate, unlike the tractor that actor
, Sam Jones drove that had a helicopter that separated.
Here is a photo of Jacko's tractor-trailer:
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Supertrain .
Supertrain is an American television drama/adventure series that ran on NBC from February 7 to May 5, 1979.
Nine episodes were made, including a 2-hour pilot episode.
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I seem to remember the intro to the show having the train-car traveling amongst some barren mountainous terrain.  I seem to remember that each section of the car-train had a different purpose, like the medical car, and the weapons car, etc.  I don't think it ran for more than a season, possibly not even completing a full season. It was live-action. It was on US television, and I don't remember any accents, so I am guessing it was American.
70s or 80s TV show, possibly post-apocalyptic with a massive train-like car
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<story-identification><tv>
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This may be Ark II, The Overlander from  Terrahawks, Supertrain, Damnation Alley, Generis II/Planet Earth or The Highwayman. The name of the TV show is most likely one of the following: Ark II, Overlander, Supertrain, the Highwayman, Damnation Alley, Genesis II or Planet Earth. 
The name of the TV show is most likely one of the following: Ark II, Overlander, Supertrain, the Highwayman, Damnation Alley, Genesis II or Planet Earth. 