Ray, I don't think I could get down and dirty into WAP primitives this evening. I'm glad that you called upon Bernard and the other intelligenci marconi for assistance. While we're at it, we may as well also call upon Jeff to do his part in explaining what he means. Jeff, you out there?
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Speaking about getting down and dirty, here's an interesting article from the March 2000 issue of OSP Magazine [OSP = OutSide Plant] featuring Level3's outside plant construction practices. BTW, I commend OSP Magazine's features, editorials and monthly tutorials to anyone who is interested in seeing feature stories each month on outside (and occasionally submarine) fiber installations, and the latest outside plant best practices, products and industry news. I've been receiving the hard copy now --which is free-- for the past two months, and have been very satisfied with it. This month's (April 2000) feature, which will not appear on the web until next month, is a treatment of Flag Telecom's latest transatlantic cable placement.
The only shortcoming that comes with reading the feature stories on the web is that they don't include photos.
FAC
ospmag.com
ospmag.com
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"DOWN 'N' DIRTY"
Plowing Through Level 3's Midwest Fiber Installation Project
by Richard Yach
Outside Plant Magazine March 2000
Recently, Level 3 Communications contracted Aldridge Electric, Inc. of Libertyville, Ill., to install
33 miles of fiber optic line as part of their massive inter-city fiber optic project. Aldridge Electric
relied on its experienced crews, as well as their machines, to achieve above-average productivity
throughout the installation--even though the firm found early in the process that they would be
working in less-than-ideal ground conditions.
This section of Level 3 Communication's project ran west from the Indiana border to the
Governor's Highway located south of Chicago, and then north for 15 more miles. Aldridge
Electric accomplished the majority of the work using three complementary strategies: plowing in
the twelve 1.25-inch diameter ducts; using its own horizontal directional drilling machines; and
subcontracting directional drilling teams to install sections that crossed roads and creeks.
Aldridge Electric, a diversified utility contractor, employs more than 500 during their peak
season. They began in late August 1999 and expected to have all 33 miles of the duct installed
by the end of October. "We averaged 3,000 feet a day," commented Bob Malek, operations
foreman for Aldridge Electric and a 20-year career veteran of underground utility installation.
"This is exceptional given the drought-like conditions that we were plowing in. This whole south
of Chicago and northern Indiana area had been dry all summer. The ground had been extremely
tough to plow, especially at the depth we were working in."
The project called for the twelve color-coded ducts to be installed with a minimum cover of 42
inches. But Aldridge Electric's standards required that the ducts be laid at a minimum of 48
inches. The twelve ducts took up 11 inches when they were stacked at the bottom of the cut,
and with the extra undercut of the heavy toepiece adding even more depth, the crew needed
their vibratory plow machine to cut, on average, 66 inches deep.
There were other considerations. While they planned for dry ground conditions, they also had to
work within a narrow right-of-way. When the company plowed alongside the road, it had a
right-of-way that varied from only 10 feet at the edge of the pavement to 25 feet at the centerline
of the two-lane highway.
"The scope of this job--the length and depth of the cut and the tough ground conditions--called
for a bigger static plow in the 50,000-lb. class," explained Malek. "But the tight, narrow
right-of-way required more maneuverability, like that of a 35,000-lb. class vibratory plow. Even
before the bid went in, we knew our Vermeer© P185 RENEGADE vibratory plow had the
attitude of a big machine along with the maneuverability of a smaller one. It would be best suited
for these tight spaces."
The contractor was told at one point by a reliable contact that this was the largest diameter duct
bundle ever plowed in the United States. "If we had attempted to use the heavier static plows,"
stated Malek, "we would have had to pre-rip once or even twice in the ground to install the large
12-duct bundle at five-feet-plus depth. With this machine, we got the job done with only one
pass."
What complicated the situation further were the many existing utilities in the same narrow
right-of-way. Some of the utilities were parallel, while others crossed the site at various angles.
For instance, along the northern part of the project, a major Amoco gas pipeline ran parallel to
the installation path. The pipeline was five to six feet to the inside of where the ductwork was to
be laid. "In some places, there was no window in which to work," said Malek. "In those
situations, we had to pothole and bore underneath."
A Case of the Bends
Getting the oversized duct bundle laid straight in the ground meant adapting to the situation. This
was something Aldridge Electric crews prided themselves on. The challenge centered around the
12 conduits that were rolled off separate 7,200-foot trailer reels. As the conduits came off the
reels, they had a tendency to retain their natural curl. If they had remained curled while being
placed in the ground, putting in the actual fiber optic lines would have been much more difficult.
To overcome this obstacle and give the asset owner a straight duct bank, Malek's crews
funneled the 12 ducts through a conveyor device mounted to the vibratory plow that combed the
ducts through rollers as they passed from the reels to the plow chute.
The plow chute or door had been specially made to funnel the 12 ducts in a
two-across-by-six-deep pattern, keeping the color-coding scheme intact and straight as the
ducts went into the ground. The ducts were subjected to a 90ø stress at the top and the bottom
of the chute during their path down the 60-inch chute. To alleviate this stress, rollers were built
into the chute to lessen the pressure from this multistacking.
"With heavier flyweights added for increased amplitude and lower frequencies, the plow had the
ability to keep the blade moving through this tough ground," stated Malek. "And its low center of
gravity allowed us to plow where larger static machines could not. Last August we plowed on
two-to-one slopes that would have been impossible for static plows to work on."
As the contractor reported their progress to Level 3 Communications, there seemed to be some
doubt that they could actually be doing what they reported. As a result, some Level 3
supervisors came out to the job site. To prove their productivity, the contractor dug up exposure
pits to show the depth of cover to the service provider. It proved that the duct banks were laid
in at 52 inches of cover--well beyond their specifications. |
