Odd buildings purpose?

October 29, 2006 1:08 PM

What are these small prefab buildings that I see while traveling on the train (and elsewhere) every once and a while?

Recently I've started to take the train up to Minneapolis every once and a while. Along the way, I've noticed quite a few copies of the same, small, prefab buildings sitting on cement blocks along the tracks. I don't have pictures (because my cameraphone sucks), but let me try and describe them:

They are about 20 feet long, 7-10 feet wide, and maybe 8 feet tall. They are made out of what looks like light-brown colored cement, are almost perfectly rectangular, and have metal doors with a short metal staircase on one end of the building. On some of the buildings' doors there are red flammable chemical warning symbols. On the opposite end is usually an air conditioner (but sometimes the AC units are located along the long side of the building). I usually see these buildings in sets of two or three, but sometimes there's just one. They're always behind chain-link, barbed-wire fences and the area inside the fence has gravel (like an electrical sub-station).

Sometimes one or more of the buildings will have a Yagi directional antenna pointing off somewhere, but otherwise I don't see any obvious connection to the outside-of-the-fence world (i.e. they're not cellphone tower support buildings or microwave relays).

As I said, I've seen a lot of these while on the train, but I've seen copies of them elsewhere nowhere near train tracks, so I don't think they have anything to do with the tracks (and they're not the smaller steel buildings that house switching and crossing gear for the tracks).

Any ideas as to what these buildings might be for? As it stands, I'm imagining them as nodes in Google's supercomputer network or something. There's gotta be a better explanation! :)

posted by yellowbkpk to Travel & Transportation (6 answers total)

Best answer: In the heydays of the dot-comm boom, railroads and telecommunications companies did big deals to lay massive amounts of fiber optic cable along railroad right of ways. It was good for the railroad companies who had thousands of miles of track right of way to offer for such narrow purpose specific use, and it was great for the communications companies, who otherwise would have been hard pressed to secure scarce interstate and intercity rights of way for their cables. Laying the fiber was a comparatively inexpensive operation, consisting of cutting shallow slit trenches, inserting fiber bundles, and closing over the trench, generally all done by relatively automated machinery. The buildings you see may be switch stations, and terminations points, that house interconnect and switching gear, and provide places for distribution network equipment to be co-located.

Once the railroads and telcos got the ball rolling, many states and cities got into similar deals, to lay intercity fiber along highway rights of way, and around cities, for metropolitan area networks and SONET rings. Again, you see the same kinds of service buildings, away from railroad tracks, but near road intersections, bridges and tunnels, where the fiber and/or underground wire networks need to have communications equipment and inter-carrier circuit termination points. Some of these buildings house standby generators and emergency fuel supplies (thus the hazmat warning signs), to keep the communications gear powered in situations of extensive power outage lasting longer than the available battery power in their UPS systems. Thus, also, the need for physical barrier security fences, and radio security links.
posted by paulsc at 2:19 PM on October 29, 2006 [2 favorites]

I'm in telecoms also; what paulsc said.
posted by ZenMasterThis at 2:44 PM on October 29, 2006

Although "inexpensive" is relative: $50-70k/mi.
posted by ZenMasterThis at 2:46 PM on October 29, 2006

Best answer: Another big advantage of following a rail right-of-way is that the resulting cable is less likely to be attacked by the bane of the industry: idiots with backhoes.
posted by Steven C. Den Beste at 3:06 PM on October 29, 2006

Response by poster: Very cool. Thanks for the answers guys.
posted by yellowbkpk at 4:21 PM on October 29, 2006

Possible urban legend: SPRINT stands for "Southern Pacific Railroad Internal Network Telecommunications", originally the railroad's own signaling infrastructure run along the rails' rights-of-way, eventually spun off into a long-distance voice company and now a general telecoms company.
posted by hattifattener at 8:24 AM on October 30, 2006