Logistical Challenge: The Very Large Array

The Very Large Array (VLA) is a radio astronomy observatory found in the San Augustin plains, around 80 kilometers west of Socorro, New Mexico. It is an important component of the National Radio Astronomy Observatory (NRAO).

The observatory contains 27 antennas, each weighing in at 209 tonnes with a dish diameter of 25 meters. There are three 21km long legs, in which the antennas can be independently moved via railroad track with a custom built lifting locomotive.

Eric Chevalier, of Tulsa, Oklahoma USA, has had the awesome opportunity to visit this site first hand and I personally thank him for his permission to use these incredible photographs on logistical challenge. I've inserted some of what Eric had to say after his visit to the VLA, so we can appreciate what it's all about first hand, please take the time read his comments, and view the remainder of his story at his own website e-tech.

The Antenna Assembly Building (AAB) is the barn in which the antennas were originally constructed and where they are brought for periodic maintenance and repair.
The AAB fascinates me for some reason I can't explain. (Heck, it's just a big building that's missing a wall!) But the AAB doesn't get any attention on the VLA's official web site, so I though it would be fun to give it a little attention here.

If you look closely in the foreground of this photo, you'll see a set of railroad tracks that lead into the AAB. Notice that there is a second set of railroad tracks that intersect at right angles.

This second set of tracks is the railway for the southwest arm of the array. I point this feature out because it ties into the following two photographs...
n the foreground is one of the two transporter vehicles that are used to move the antennas around the complex. (The VLA has two such transporters; the second can be seen parked just in front of the AAB.)
The transporters roll on parallel standard-gauge rairoad tracks. Each arm of the VLA consists of one such railway. At various points along the main railway are spurs that branch off at right angles to the individual antenna mount locations.

The transporter works by rolling underneath an antenna. Hydraulic jacks on the transporter then lift the antenna off of its mounting piers and the transporter and antenna combination then roll away to the next stop.
Another view of the transporter. Sorry, but I haven't a clue as to which end is the "front" and which is the "back"!
Here's something fascinating that I hope to see someday: as I mentioned, there are short spurs that lead from the antenna locations to the main railway of each arm. The spurs intersect the main railway at sharp, 90-degree angles, just as you might have noticed in the photo of the AAB, above.

If we take the southwest arm as an example, suppose a transporter is bringing an antenna back to the barn for repairs. Once the transporter reaches the intersection you see in the AAB photo, how does it change directions?

The only thing I can figure is that there are hydraulic jacks on the bottom of the transporter that lift the entire vehicle off the ground enough so that the wheel assemblies can now be rotated 90 degrees to match the orientation of the spur! I would definitely like to watch the movement of an antenna someday so I can see, firsthand, how this is performed!
My attempt to be a little bit "arty" with the camera; one of the southwest arm's antennas framed underneath the transporter.