There’s a fascinating article about how the Shetland Islands is putting in its next generation of fiber infrastructure. It’s meant to connect to the new SHEFA2 cable, which is bringing a direct fiber connection to the island, replacing the existing microwave link that has simply not been able to keep up lately. But the Shetlands have, shall we say, rather few people and thus fiber is hard to justify even with a government grant.
They’re using a ‘Ditch Witch’ to dig a trench right down the main roadways. And by trench, I mean a really small hole in the ground you could drive over (though they’ll fill it of course). It’s just 20mm wide and 100mm deep, or about three quarters of an inch wide and 4 inches deep, and the fiber along with foam packing goes on top followed by a layer of concrete and tar.
The costs are far cheaper than earlier plans, and they’d have to be in order to hook up a mere 22k people – or however many of those actually live in town. Otherwise, you’re talking about FTTS (Fiber to the Sheep). Great scenery up there though.
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Armchair engineering is always suspect, but looking at the aerial and Google Streetviews of this 13.9 mile route show it to be a candidate for traditional trenching, assuming a 20+ year conduit life.
There are no massive rock formations just off the right of way and a lot of the path is rural. Weather averages show mostly above freezing. It would be interesting to know if this was using the sealed or unsealed conduit.
Also, 60 m/day (<200 ft/day) for conventional? Sounds low, unless the substrate is mostly rock, which it might be, though the Shetland Times article wasn't explicit.
Some comments on this procedure that are, as the car guys say, “unencumbered by the thought process”
There are some pros and cons to this method of installing fiber. I have seen some advertising for this over the past few years.
Pros: relatively fast process as the installation and cleanup is minimal. Low risk excavation as you are not going very deep. relatively cheap as the crew sizes and equipment required are smaller.
Cons: the fiber is not as protected in that it is much shallower, it appears to be somewhat limited in fiber capacity, ie number of fibers (although one fiber can still carry a hell of a lot of infomation), crossing some obstacles still seems to require more conventional excavations or bores,
Just some more armchair engineering with all the pitfalls mentioned earlier
Micro duct / micro fiber
144count fiber x (2 or 3) ducts.
On the other hand, in the Shetlands there are fewer dangers to fiber under a road than elsewhere. Perhaps it’s the best fit for this geography.
Readers may also find this article/video/commentary of interest:
Farmers Digging Up for Fibre
Benoit | Fibereveolution Blog
http://siliconinvestor.advfn.com/readmsg.aspx?msgid=26840958
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Biggest challenge is to have the municpalities approve and permit-especially in the colder climates as it can jeopardize the integrity of the road base as they go deeper than the traffic sensor loops and can be an area of cracking/heaving no matter how good the cut is sealed. Maybe a good option as a last resort.
The speeds quoted for the traditional method is a tad on the slow side but this is due to two problems…. yip, a lot of rock but more of a problem is that the sides of the roads are already full of services and the maps are vaugue on where we could and couldn’t dig. The cost quoted was too high to make the case for doing it….
In response to Gary’s reply, we are lucky enough to have our Council’s Roads Dept onside. It was them that recommended the process. :-).
It’s all new and we are wary of making too many claims about how brilliant it is until we give it a go. Initial test results are good but we probably won’t be doing much more until after we have seen how a hard winter effects it.
Thanks Marvin, for a firsthand view actually coming out of the Shetlands themselves!
No worries Rob.
We have a short video at http://www.youtube.com/watch?v=qelQYS7hGm0
Unfortunately the guys from Ditch Witch had to leave a day early so the contractor pulled the actual slot trenching forward a day so I missed it…