You wouldn't want to break down here would you? It's funny how some stories come back to you like Halley's comet... Or a dose of fried onions... But speaking of things 'Astral' I'm grateful to Simon Wood that young roister-doister at Mercedes-Benz who very kindly provided me with these pictures of a special Scheurle carrier which if I remember correctly is being used to move giant lenses or mirrors, (or pasties... Well something giant anyway) as part of the extension of the European Southern Observatory in Chile... Which I spotted in the latest edition of MB's 'Transport' magazine.
You can clearly see how wide those carriers were and the fact that it took a while to get them up into the high Andes to the observatory... The photographer was Luis Roa/ALMA and click through here for one more.
Bit of a tight squeeze getting there too. And guess what... I've just found the original post... Enjoy!
Now you don't need Biglorryblog to tell you that ALMA (short for Atacama Large Millimetre Array) is the name of the observatory that sits on the high plateau of the Chilean Atacama Desert. Nor that the largest antenna facility in the world is located there at 5,100 metres (that's a lung-busting 16,278ft to you) and is used to research the universe. And you probably also know that the ALMA project is the result of a joint effort between Europe, East Asia, North America and Chile with the European involvement being managed by the Munich-based ESO (European Southern Observatory) who was also responsible for procuring the antenna transporters.
But what you might not know is how the kit for the project is carried up there. After all, it's no good having an antenna if you can't move it around to where you want it to go. So naturally ESO turned to the Pfedelbach-based special vehicle manufacturer Scheuerle to come up with some special transporters to carry them. (BLB readers will recall the German heavy haulage equipment manufacturer was recently featured in our blogs on Venezuelan heavy haulage... But I digress). Note the Actros tractor up front above.
The two antenna transporters, called 'Otto' and 'Lore' (no really..and that's one of them being moved on the road above - and just see how wide they are) are pretty specialised. After all radio antennas used in an antenna field have a 12m parabolic dish and weigh115 tonnes each. Depending on the research programme, a total 66 antennas must be continually repositioned around the 200 or so prepared bases which cover a distance of 15km...
However, the real challenge for the Mercedes trucks used on the move - to BLB it looks like a mixture of old SK Powerliners and newer Actros artics - carrying those antenna transporters (well they're not going to get up the mountain on their own are they?) is working in the high altitude where engine performance can be reduced by up to 50% because of the oxygen-depleted air. The Atacama plateau is also one of the driest areas on earth, shaped by extreme daily temperature changes between +30°C during the day falling to -15°C at night.
Having arrived at the Port of Mejillones on the Chilean coast the two antenna transporters (errr sorry.....'Lore' and 'Otto') each weighing 135 tonnes started their journey on the back of Scheuerle multi-axle low loaders to the final destination in the Chilean Atacama Desert. 
The 417kms of road had a few interesting bits to overcome--like the 3,450m (11,316ft) high Paso Cordillera de Sal. And that does look 'narrow' doesn't it...! It was a huge challenge for the driving ability of the transporters because of the rock formations.
And going downhill wasn't that easier either and again you can see the overhang on each side. Each outfit had a 'puller' and a 'pusher'...in this on you can see what looks like a 6x6 ballasted SK Merc 'in back'!
I thought air at high altitude is at reduced pressure rather than "oxygen-depleted" which is to say there is "less of everything" not just oxygen.
With turbocharged engines the problem of power loss is much reduced as the reduced atmospheric (back) pressure makes it easier for the smoke to get out of the chimney, enabling the turbo to run faster and therefore suck in more of the thin stuff; this more or less compensates the atmospheric pressure loss.
I do remember having to adjust fuel delivery downwards on Caterpillar (dozer) turbo engines many years ago due to concern about over-revving their turbos at over 4000 feet altitude. Possibly modern blowers can better handle the revs?