A large highway interchange is being rebuilt in Montréal (Turcot) and
this requires that the CN mainline tracks out of downtown be moved a few
hundred metres to the north for a couple of kilometres until it rejoins
the existing alignment.
Part of the contract involves the cost of moving the fibre trunks along
with the tracks. (old alignment will become commercial properties).
So they have new cable that goes through the new alignment and joins the
old one at both ends. So they'll have hundreds of strands to splice.
When doing that type of work, how much downtime can be expected for each
strand?
Would they typically use patch panels in central offices to move a
customer to a spare strand while they splice their assigned strand to
use the new cable segment (and then move traffic back to that assigned
strand?). Or would they switch customers around to new strands and
update their documentation on which customer is on which strand?
Or do they do nothing at patch panels in COs and just take whatever time
it is needed to have crews at both ends of the work site splice each
strand at same time (I assume about 5 minutes outage for each strand?)
Would they normally involve the customer advising them of upcoming
outage? Would the folks working trackside be limited to overnight hours
to make outages less significant, or do they work around the clock ?
I'd expect at least a couple of hours of outage while the cable is reconnected.
When doing the move on the live cable (assuming 1 cable). There will
be a splicing crew at each end of the move. They will then break a
tube or ribbon at a time and splice into the new cable.
Splicing unused portions of the cable and then moving patches is also
done. In my experience, it's much more common to resplice on the
existing strands.
A large cable will take quite a while to resplice, likely more than
just overnight depending on the size of the cable.
Jay
If it is in the railroad RoW they may be restricted to daylight working
only. Check with your provider or OSP crew.
Yup. Railroad work is complex just because you have to coordinate with the railroad owner and they have to be onsite for all work. The cost of going underground vs aerial is also astronomical in many cases.
- Jared
I don't think there is virtually any aerial in Europe. So given the cost difference why is virtually all fiber buried on this side of the Atlantic?
Yeah,
Being somehow familiar with how things operate when it involve Quebec Govt and the Fed Govt... Expect hell. Pray for purgatory. Rejoice if it takes less than 3 months.
PS: At least we have very good, and dedicated, cabling crews.
=D.
But yeah, there is work being done to reduce the downtime to a manageable timeframe. If not simply redundancy being added to allow for the time to splice that bad boy.
In this particular case, the government is giving CN new land, and once
construction crews for the highway/interchange have moved on, segments
are opened for CN to bring its crews to install tracks, portals,
signals, track service road etc.
The main contract gives CN responsability to handle the telecom under
its tracks, so I assume that once CN is given access to the full length
of new right of way, it will coordinate with the various telecom
companies that rent space under its tracks to do the move.
The move is expected in summer 2018. (during next winter, the last
remaining elevated structures that block the new CN right of way will be
torn down, allowing CN to then finish the work starting in spring. (it
does not lay tracks in winter).
Aerial is simple and fast... pull the cable through a stringer, move to the next pole and repeat; when a section (about a mile) is done, it's hoisted into the air and tied to the pole. The stringers are then moved to the next mile of poles and the process repeats.
Buried stuff requires a great deal of planning, permitting, and insurance. You have to know everything that's ever been stuffed in the ground within half a mile of where you're working to avoid the inevitable cutting of something important -- gas, water, sewer, power, other telcom, even vacuum tube lines and subways. And then you need trenching gear to get stuff in the ground, and crews to come along behind to remediate the "environmental damage".
(Once the conduit is in the ground, it's a trivial matter to blow whatever you need through it.)
Pretty much. Here is an example of permitting requirements for underground. Underground costs 5-12/foot (or more in urban areas) whereas aerial can be as low as $2/foot.
i'm sure theres plenty of aerial in europe. usually carried on e.g.
the top messenger cable on pylons - given i've attended talks about
the issues of fixing such fibre after storms in Scotland.... 
Are cables in railway right of way considered "burried stuff" from the
point of view of all the regulatory approvals since it is on private
land (railway's) ?
I take it that it is the railway which burries a new cable in its
ballast (since it knows where other cables are burried, has to handle
cable crossing its bridges etc)?
In the specific case of Turcot in Montréal, the government was in charge
of cleaning the land, removing any obstructions (such as a major sewer
collector which had to be moved) etc, and even drained and compressed
the ground before handing it over to CN to build its tracks. So CN got
a clean slate, ready to lay tarp, ballast and tracks (and later string
fibre).
(ironically, that land used to belong to CN and was the Turcot rail yards).
Aerial's not that rare in Europe (rural areas, sometimes even close to
metro).
Cheers,
mh
That depends on the country. Here in Denmark it is not possible to get
rights to put up any aerial at all. The cost difference is irrelevant when
you have no option but to put it in the ground.
Not only is there no new aerial installations here but the old ones are
taken down. Very little is left by now and in a few years it will all be
gone. The municipalities want it pretty and wires in the air is ugly.
One advantage however is that buried stuff usually survives storms better.
That depends on the country. Here in Denmark it is not possible to get
rights to put up any aerial at all. The cost difference is irrelevant when
you have no option but to put it in the ground.
Not only is there no new aerial installations here but the old ones are
taken down. Very little is left by now and in a few years it will all be
gone. The municipalities want it pretty and wires in the air is ugly.
One advantage however is that buried stuff usually survives storms better.
Right. Here in France it (aerial running along with copper) happens
even close to metropoles (like Paris).
mh
The the USA, we have tornadoes, hurricanes, nasty wind and lightning, ice
accumulation on lines, and idiot squirrels that like to eat fiber. Buried
fiber over time will end up being cheaper than aerial once you factor in
maintenance and repair. Add to that the additional cost of pole studies,
replacement and attachments that the electric utility demands to be on
their poles. When you're paying them for a pole study so that they can tell
you that the pole isn't strong enough or tall enough to provide clearance,
then paying them to replace the pole to make it sufficient, and then paying
them monthly after that to be on the pole, just putting it in the ground
starts making a lot of sense.
We were affected by a fiber cut a while back caused by a truck that wiped
out several electric poles. It was over 24 hours before the fiber company
was even allowed access to the poles, because the electric utility wouldn't
release them until they were finished. There's a lot to be said about
controlling your own destiny by putting the fiber in the ground where you
can work on it whenever you need to.
You need insurance regardless of aerial or buried. 1/2 mile might be an
exaggeration. Telcom doesn't do much trenching. Vibratory plow in open
areas where there's nothing to contend with, but in urban, it's almost
always directional boring. The only time we hit anything is when the other
utilities fail to locate at all or fail to locate correctly.
The easiest thing is to contract with a cable construction company that
already has all the skills, insurance and equipment, and let them deal with
it.
That depends on the country. Here in Denmark it is not possible to get
rights to put up any aerial at all. The cost difference is irrelevant when
you have no option but to put it in the ground.
Not only is there no new aerial installations here but the old ones are
taken down. Very little is left by now and in a few years it will all be
gone. The municipalities want it pretty and wires in the air is ugly.
One advantage however is that buried stuff usually survives storms better.
Right. Here in France it (aerial running along with copper) happens
even close to metropoles (like Paris).
mh
I expect it is mostly northern Europe that is doing the no aerial thing.
I agree as an European resident that is varies by country, but my impression is that it is a lot less. For example, fiber cuts on the European racetrack (London/Paris/Frankfurt/Amsterdam/London) seems to involve buried cable. It may just be a difference in regulatory regimes.
- R.