U.S. patent application number 10/786298 was filed with the patent office on 2005-09-01 for micro trench duct placement.
Invention is credited to Purcell, Steven L..
Application Number | 20050191133 10/786298 |
Document ID | / |
Family ID | 34750485 |
Filed Date | 2005-09-01 |
United States Patent
Application |
20050191133 |
Kind Code |
A1 |
Purcell, Steven L. |
September 1, 2005 |
Micro trench duct placement
Abstract
A method of placing cable within concrete or asphalt includes
cutting a trench into the concrete or asphalt. The method further
includes placing a tubular material having a hollow inner diameter
within the trench. The method also includes placing the cable
within the tubular material.
Inventors: |
Purcell, Steven L.;
(Richardson, TX) |
Correspondence
Address: |
MCI, INC
1133 19TH STREET NW
WASHINGTON
DC
20036
US
|
Family ID: |
34750485 |
Appl. No.: |
10/786298 |
Filed: |
February 26, 2004 |
Current U.S.
Class: |
405/157 |
Current CPC
Class: |
G02B 6/504 20130101 |
Class at
Publication: |
405/157 |
International
Class: |
E03B 007/10 |
Claims
1. A method, comprising: cutting a trench in a surface of the
roadway; placing a duct in the trench; placing a spacer within the
trench on top of the duct, filling the trench with a sealer;
placing a first cable within the duct; pulling the first cable out
of, and through, the duct; and placing a second cable within the
duct without removing the sealer within the trench.
2. The method of claim 1, wherein the first cable comprises utility
cable.
3. The method of claim 1, wherein the first cable comprises optical
fiber cable.
4. The method of claim 1, wherein the trench is cut to a depth of
approximately 3.5 to 4.0 inches beneath the surface of the
roadway.
5. (canceled)
6. The method of claim 1, wherein the duct comprises high density
polyethylene (HDPE) duct.
7. The method of claim 4, wherein the trench is cut to a width of
approximately 0.5 inches.
8. (canceled)
9. The method of claim 1, wherein the spacer comprises a tubular
shape.
10. The method of claim 9, wherein a diameter of the spacer is
approximately 25% larger than a width of the trench.
11. The method of claim 1, further comprising: placing sand within
the trench.
12. The method of claim 1, wherein the sealer comprises
bitumen.
13. The method of claim 12,wherein the sealer is heated to between
approximately 325 and 375 degrees Fahrenheit before filling the
trench.
14-22. (canceled)
23. A method of placing cable within concrete or asphalt,
comprising: cutting a trench into the concrete or asphalt to a
depth of approximately 3.5 to 4.0 inches from a surface of the
concrete or asphalt; placing a tubular material having a hollow
inner diameter within the trench; placing a spacer on top of the
tubular material, wherein the spacer comprises a water impermeable,
heat resistant material: filling at least a portion of the trench
with a sealer; placing a first cable within the tubular material;
removing the first cable from the tubular material without removing
the sealer from the trench; and placing a second cable within the
tubular material without removing the sealer from the trench.
24. The method of claim 23, wherein the first cable comprises fiber
optic cable.
25. (canceled)
26. The method of claim 23, wherein the spacer has an outer
diameter that is approximately 25% greater than a width of the
trench.
27. (canceled)
28. The method of claim 23, wherein the tubular material comprises
high density polyethylene (HDPE).
29. The method of claim 23, wherein the tubular material comprises
an outer diameter of approximately 0.5 inches and wherein the inner
diameter comprises approximately 0.375 inches.
30. (canceled)
31. The method of claim 23, wherein the sealer comprises bitumen
heated to between 325 and 375 degrees Fahrenheit.
32. The method of claim 1, wherein the first cable is pulled out
of, and through, the duct without removing the sealer within the
trench.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to outside utility
cable placement techniques and, more particularly, to utility cable
placement using micro trench ducts.
BACKGROUND OF THE INVENTION
[0002] With the explosion in communication via the Internet in
recent years, there has been a corresponding increase in demand for
high-speed bandwidth, such as that provided by fiber optic cables.
However, provision of fiber optic cabling to the many locations,
where it is in demand, has been problematic. Underground provision
of fiber optic cabling has been a primary means of providing the
cabling to various locations. Underground cable placement, though,
requires excavation and, often, considerable surface destruction to
permit the placement of the fiber optic cabling. Additionally, when
the cable is placed in the ground, it is difficult to repair
without having to re-excavate the area so that the cable can be
removed. Furthermore, placement of cable directly in the ground
leaves the cable in an unprotected state where it is susceptible to
injury due to environmental conditions or external events on, or
under, the surface of the ground.
[0003] Therefore, there exists a need for methods and assemblies
for installing subsurface utility cables, such as fiber optic
cables, that reduce surface destruction when installing the cables,
improves the capability to repair subsurface cables once they are
installed, and protects subsurface utility cables so as to reduce
damage due to environmental conditions or external events.
SUMMARY OF THE INVENTION
[0004] In accordance with one aspect consistent with the principles
of the invention, a method of placing cable beneath a roadway
includes cutting a trench in a surface of the roadway and placing a
duct in the trench. The method further includes filling the trench
with a sealer and placing cable within the duct.
[0005] According to another aspect consistent with the principles
of the invention, an assembly for carrying cable within a trench
cut in concrete or asphalt includes a duct comprising a tubular
material having a hollow inner diameter and an outer diameter that
is approximately equal to a width of the trench. The assembly
further includes cable placed within the hollow inner diameter of
the duct.
[0006] According to yet another aspect consistent with the
principles of the invention, a method of placing cable within
concrete or asphalt includes cutting a trench into the concrete or
asphalt to a depth of 3.5 to 4.0 inches from a surface of the
concrete or asphalt. The method further includes placing a tubular
material having a hollow inner diameter within the trench and
placing the cable within the tubular material.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] The accompanying drawings, which are incorporated in and
constitute a part of this specification, illustrate exemplary
embodiments of the invention and, together with the description,
explain the invention. In the drawings,
[0008] FIG. 1 illustrates a micro trench according to one aspect of
the invention;
[0009] FIG. 2 is a flow chart that illustrates an exemplary process
consistent with an aspect of the invention;
[0010] FIG. 3 illustrates an exemplary cutting of a ninety degree
turn according to an aspect of the invention;
[0011] FIG. 4 illustrates an exemplary core bore according to an
aspect of the invention;
[0012] FIG. 5 illustrates an exemplary micro trench entrance to a
hand hole according to an aspect of the invention;
[0013] FIG. 6 illustrates an exemplary micro trench entrance to a
manhole according to an aspect of the invention;
[0014] FIGS. 7A and 7B illustrate an exemplary micro trench
entrance through a wall according to an aspect of the
invention;
[0015] FIG. 8 illustrates an exemplary micro duct placement process
according to an aspect of the invention;
[0016] FIG. 9 illustrates an exemplary process for placing a micro
trench spacer according to an aspect of the invention;
[0017] FIGS. 10A and 10B illustrate spacer and sand placement in
the micro trench ninety-degree turn of FIG. 3 according to an
aspect of the invention; and
[0018] FIG. 11 illustrates an exemplary process for placing a micro
trench sealer according to an aspect of the invention.
DETAILED DESCRIPTION
[0019] The following detailed description of the invention refers
to the accompanying drawings. The same reference numbers in
different drawings may identify the same or similar elements. Also,
the following detailed description does not limit the invention.
Instead, the scope of the invention is defined by the appended
claims and their equivalents.
[0020] Methods and assemblies consistent with the present invention
enable the placement of subsurface utility cables through the use
of subsurface micro trenches and micro ducts, installed in roadway
concrete or asphalt, that require minimal surface trenching, permit
easy repair of the utility cables, and protect the utility cables
from environmental conditions or external events. Consistent with
one aspect of the invention, micro trenches may be cut
approximately three to four inches into a roadway surface, and a
micro duct that includes a high load rating material may be placed
into the micro trench for carrying the subsurface utility cables. A
spacer may be placed on top of the micro duct along the length of
the micro trench to enhance structural rigidity and to protect the
micro duct. A sealer may then be placed in the micro trench, over
the micro duct and spacer, to fill up the trench made in the
roadway surface.
[0021] Subsurface utility cables may then be inserted in the micro
duct subsequent to placement of the micro duct in the micro trench.
Subsurface utility cables may, thus, be easily repaired after
placement into the micro trench by pulling the cables out through
the micro duct via, for example, a hand hole or a manhole. The
micro duct and spacer may additionally protect the subsurface
utility cables from environmental conditions and external events
that may otherwise damage the utility cables.
Exemplary Micro Trench
[0022] FIG. 1 illustrates a cross section of an exemplary micro
trench 100 that may be constructed in accordance with exemplary
processes consistent with the invention. Micro trench 100 may
include a channel in a roadway surface 105 for receiving a micro
duct 125. For example, micro trench 100 may be cut through roadway
surface 105 to a depth of d.sub.1 110 in roadway material 115.
Depth d.sub.1 110 may range from about 3.5 to about 4.0 inches. In
one exemplary implementation, d.sub.1 may be 4.0 inches.
Additionally, micro trench 100 may be cut to a width w 120 through
roadway surface 105. Width w 120 may range from about 0.50 inches
to about 0.55 inches. In one exemplary implementation, w 120 may be
0.5 inches. Roadway material 115 may include concrete or
asphalt.
[0023] After the cutting of micro trench 100, a micro duct 125 may
be placed in the bottom of micro trench 100. Micro duct 125 may
include a hollow tubular conduit for receiving cable 130, such as,
for example, any type of utility cable. In one implementation, for
example, micro duct 125 may be made of HDPE and may further be HD20
load rated. Micro duct 125 may include an inside diameter that
ranges from about 0.35 inches to about 0.40 inches. Micro duct 125
may further include an outside diameter that ranges from about
0.475 inches to about 0.525 inches. In one exemplary
implementation, micro duct 125 may include a 0.375 inch inside
diameter and a 0.5 inch outside diameter. Cable 130, such as, for
example, fiber optic cable, may be installed in micro duct 125 to
run through the inside diameter of the duct. Cable 130 may also
include any type of utility cable that may fit within the inner
diameter of micro duct 125.
[0024] After placement of micro duct 125, a spacer 135 may be
placed in micro trench 100. Spacer 135 may include a substantially
solid tubular member that enhances structural rigidity and provides
protection to cable 130 from, for example, moisture and other
environmental conditions that exist on the roadway surface 105.
Spacer 135 may, for example, be made out of a material that is
water impermeable and heat resistant to approximately 400 degrees
Fahrenheit. In some implementations, for example, spacer 135 may be
placed on top of micro duct 125 at a depth d.sub.2 135 below
roadway surface 105. Depth d.sub.2 135 may be at least 2 inches,
but not more than 3 inches. Spacer 135 may have a diameter that is
approximately 25% larger than trench width w 120 to ensure a tight
seal between micro duct 125 and side surfaces of micro trench 100.
In one exemplary implementation, spacer 135 may have a 5/8 inch
diameter for a 1/2 inch trench.
[0025] After placement of spacer 135, a sealer 140 may be placed in
micro trench 100. Sealer 140 may seal micro trench 100 to protect
cable 130 from environmental conditions. Sealer 140 may include,
for example, bitumen, though other sealing materials may be used.
The thickness of sealer 140 may be between two and three inches,
and should overlap the edge of micro trench 100 by about two inches
(not shown). The total width of sealer 140 on the roadway surface
105, therefore, should be approximately 4.5 inches (assuming a
trench width w 120 of 0.5 inches). Sealer 140 may protrude no more
than 1/4 inch above the roadway surface 105.
Exemplary Trench Cutting Process
[0026] FIG. 2 is a flowchart that illustrates an exemplary process,
consistent with the present invention, for cutting a micro trench
100. The exemplary process may begin with cleaning of the roadway
surface 105 where the trench is to be cut [act 205]. The roadway
surface 105 may be cleaned, for example, with high-pressure water
or air to remove debris from the roadway. A route for micro trench
100 may then be defined on the roadway surface 105 [act 210].
Defining micro trench 100 may include, for example, marking the
route for micro trench 100 with any appropriate marking technique
or mechanism. Such techniques or mechanisms may include, for
example, marking the route for micro trench 100 with a chalk line.
Such techniques or mechanisms may further include, for example,
using lasers, GPS, inertial navigation systems, etc. for locating
and marking the route for micro trench 100.
[0027] A micro trench 100 may then be cut in the roadway material
115 along the defined trench route [act 215]. For example, standard
1/2 inch concrete saw blades, turned so that the blade cuts
backwards (i.e., upcuts), may be used to cut a micro trench 100 of
width w 120 and depth d.sub.1 110. The cutting machine may be used
without water (i.e., dry cut), with a dust collection and
containment system attached to the back of the blade area to catch
the debris and dust.
[0028] When possible, micro trench 100 may be cut parallel or
perpendicular to other pavement attributes (e.g., expansion joints,
striping, etc.). The trench depth d.sub.1 may be between 3.5 and 4
inches and should be inspected after cutting to ensure gradual
transitions are maintained. Transitions in depth at the bottom of
micro trench 100 should be smooth and may be achieved with a
hand/cut-off saw. Trench width w 120 may be equal to the outer
diameter of the micro duct 125 that is to be placed in micro trench
100. For example, if micro duct 125 to be placed has an outside
diameter of 0.5 inches, then width w 120 should be 0.5 inches.
[0029] If ninety degree turns in micro trench 100 are required,
then trench 100 may be cut to each running line, and then a
forty-five degree angle may be cut between the two lines. For
example, a micro trench ninety-degree turn 300 is illustrated in
FIG. 3. To make the ninety degree turn, a first saw cut 305 is made
along the trench running line and a second saw cut 310 is made
perpendicular to the first saw cut 305. A forty-five degree saw cut
315 may then be made that over cuts each end of the first and
second saw cuts 305 and 310. At the intersection of the forty-five
degree saw cut 315 and the first and second saw cuts 305 and 310,
areas 325 may be notched out to an approximate six-inch radius. The
forty-five degree saw cut 315 may extend approximately one saw
blade in length between the first and second saw cuts 305 and
310.
[0030] For entering hand holes, manholes, or building walls, a core
bore may be made through an external surface of the hand hole,
manhole or building wall. For example, as shown in FIG. 4, a core
bore 400 may be drilled through the concrete, rock or other
material 405 that comprises the hand hole, manhole or building
wall. In some implementations, for example, core bore 400 may
include an outer diameter of one inch.
[0031] FIG. 5 illustrates a specific example of a core bore 400
entrance to a hand hole 505 through a side surface of hand hole 505
below an existing grade 510. Micro duct 125 and cable 130 may run
through core bore 400 entrance into hand hole 505. FIG. 6
illustrates another specific example of a core bore 400 entrance to
a manhole 605 through a surface of the manhole 605 below an
existing grade 610. Micro duct 125 and cable 130 may run into core
bore 400 entrance into manhole 605.
[0032] FIGS. 7A and 7B illustrate another specific example of a
core bore 400 entrance through a wall 705 below an existing grade
710. Micro duct 125 and cable 130 may be run through core bore 400
entrance through wall 705 into, for example, the interior of a
building.
[0033] Returning to FIG. 2, subsequent to cutting of micro trench
100, the trench may be cleaned [act 220]. Micro trench 100 may be
cleaned, for example, with a blower or compressed air to remove all
dust and debris.
Exemplary Micro Duct Placement Process
[0034] FIG. 8 is a flowchart that illustrates an exemplary process,
consistent with the present invention, for placing micro duct 125
in micro trench 100. The exemplary micro duct placement process may
begin with an inspection of micro trench 100 [act 805]. Micro
trench 100 may be inspected, for example, to ensure that the trench
is free of debris. Dirt, debris and surface moisture should be
removed from at least six inches on each side of micro trench 100
prior to placement of micro duct 100. HD20 load rated micro duct
125 may be obtained [act 810] and inspected to ensure that it is
the appropriate inside and outside diameter. Micro duct 125 may
then be placed in the bottom of micro trench 100 uni-directionally
(i.e., placed only in one direction along the trench) [act 815].
Micro duct 125 usually should not be placed from two different
directions (i.e., bi-directionally). Micro duct 125 may be placed
at the bottom of micro trench 100 by pressing it into the trench
using a steel wheel with sufficient weight to ensure that slack is
removed and there is no space between the duct and the bottom of
trench 100. If the micro duct 125 that is used does not contain a
locate wire, then a tracer wire may be installed for locate
purposes [act 820]. The tracer wire may, for example, include a
coated 14 gauge copper wire installed on top of micro duct 125 and
under spacer 135.
[0035] For entering hand holes, manholes, or building walls, micro
duct 125 may be inserted through a core bore 400 that extends
through an external surface of the hand hole, manhole or building
wall. For example, as shown in FIG. 4, micro duct 125 may be
inserted through a core bore 400 that extends through concrete,
rock or other material 405 of the hand hole, manhole, or building
wall. Grout 410, such as, for example, epoxy grout, may be used
between micro duct 125 and core bore 400 to seal any gap that
exists between core bore 400 and micro duct 125.
[0036] FIG. 5 illustrates a specific example of micro duct 125
inserted through a core bore 400 that extends through an external
surface of a hand hole 505. FIG. 6 illustrates another specific
example of micro duct 125 inserted through a core bore 400 that
extends through an external surface of a manhole 605. FIGS. 7A and
7B further illustrate another example of micro duct 125 inserted
through a core bore 400 that extends through a wall 705, such as a
building wall. The cable 130 within micro duct 125 may be inserted
into a splice case 720 of a pull box 715.
Exemplary Spacer Placment Process
[0037] FIG. 9 is a flowchart that illustrates an exemplary process,
consistent with the present invention, for placing one or more
spacers in micro trench 100. The exemplary process may begin with
the inspection of micro trench 100 [act 905]. Micro trench 100 may
be inspected, for example, to ensure that the trench is free of
debris. An appropriate sized spacer 135 may then be obtained for
placing in micro trench 100 [act 910]. The diameter of spacer 135
may be 25% larger than the width w 120 of micro trench 100 to
ensure a tight seal between micro duct 125 and sealer 140.
[0038] Spacer 135 may be placed on top of micro duct 125
uni-directionally (i.e., only in one direction in trench 100) [act
915]. Spacer 135 usually should not be placed from two different
directions (i.e., bi-directionally) and normally should not be
spliced to begin a new piece or to make a repair. Instead of
splicing, adjacent spacers 135 may be overlaid by at least six
inches. Spacer 135 may be placed on top of micro duct 125 by
pressing spacer 135 into micro trench 100 using a steel wheel with
sufficient weight to ensure that slack is removed and that there is
no space between micro duct 125 and the bottom of spacer 135.
[0039] Once all spacers 135 in the trench line are in place, sand
may be added to all areas in micro trench 100 where spacers 135
will not protect micro duct 125 from hot sealer 140 [act 920]. The
sand should be added such that its height is the same as the top of
spacer 135. The sand may be fine grade and dry. After installation,
the micro trench 100 may be inspected [act 925]. Micro trench 100
may be inspected, for example, to ensure that the top of spacer 135
or sand, if any, is at depth d.sub.2 below the roadway surface 105.
Depth d.sub.2 may by at least 2 inches, but no more than 3 inches
from the surface.
[0040] FIGS. 10A and 10B illustrate the placement of spacers 135
within a micro trench undergoing a ninety-degree turn, as
previously shown in FIG. 3. A beginning 1005 of a first spacer A
may be placed on top of micro duct 125, within saw cut 305, and
further placed such that the end 1010 of the spacer A ends at one
end of the forty-five degree saw cut 315. A beginning 1015 of a
second spacer B may be placed on top of micro duct 125, within saw
cut 310, and further placed such that the end 1020 of the spacer B
ends at another end of forty-five degree saw cut 315. Spacers A and
B may, thus, be double stacked 1025 over a portion of forty-five
degree saw cut 315. Subsequent to placement of spacers A and B, the
void area 1030 (FIG. 10B) at the intersection of saw cut 305 and
saw cut 315, and the intersection of saw cut 310 and saw cut 315,
may be filled to the top level of the spacers with sand.
Exemplary Sealer and Cable Placment Process
[0041] FIG. 11 is a flowchart that illustrates an exemplary
process, consistent with the present invention, for placing sealer
in micro trench 100 subsequent to micro duct placement. The
exemplary process may begin with obtaining sealer 140 that is to be
placed in micro trench 100 [act 1105]. Sealer 140 may include, for
example, bitumen, though other sealing materials may be used.
Seated 140 may be heated and then placed in micro trench 100 [act
1110]. Heated sealer 140 may, for example, be placed in micro
trench 100 over spacer 135 in multiple unidirectional passes.
Heated sealer 140 may include, for example, a thickness of d.sub.2.
In some implementations, thickness d.sub.2 may range from about 2
inches to about 3 inches.
[0042] If the trench requires more than 3 inches of sealer, then a
spacer or sand may be used to fill the additional void between the
top of spacer 135 that is placed on top of micro duct 125. Sealer
140 may be heated to a temperature of between 325 degrees
Fahrenheit (F) to about 375 degrees F before placement in micro
trench 100. The final pass to place sealer 140 may be made after
previously placed sealer has had time to cool and contract [act
1115] and may overlap the edge of micro trench 100 by approximately
two inches. Sealer 140 may be placed to include no more than 1/4
inch of sealer above roadway surface 105.
[0043] After placement of sealer 140, the cable 130 may be placed
in micro duct 125 [act 1120]. A pulling method, for example, may be
used to pull cable 130 through micro duct 125. Pulling tension,
however, usually should not exceed 300 lbs., therefore, a 300 lb.
break-away may be used. Cable blowing techniques may also be used
to place cable in micro duct 125.
CONCLUSION
[0044] Consistent with the invention, a technique may be employed
that uses micro ducts that can be placed in micro trenches under
roadway concrete or asphalt to carry subsurface utility cables.
Micro trenches may be cut approximately three to four inches into
the roadway surface and a micro duct that includes a high load
rating material may be placed into the micro trench for carrying
the subsurface utility cables. Subsurface utility cables may be
inserted in the micro duct and may then be easily repaired by
pulling the cables out through the micro duct via, for example, a
hand hole or a manhole. The micro duct additionally protects the
subsurface utility cables from environmental conditions and
external events that may otherwise damage the utility cables.
Methods and assemblies, consistent with the invention, thus, permit
the installation of subsurface utility cables that require minimal
trenching, permit easy repair of the utility cables, and protect
the utility cables from environmental conditions or external
events.
[0045] The foregoing description of embodiments of the present
invention provides illustration and description, but is not
intended to be exhaustive or to limit the invention to the precise
form disclosed. Modifications and variations are possible in light
of the above teachings or may be acquired from practice of the
invention. While series of acts have been described with respect to
FIGS. 2, 8, 9 and 11, the order of the acts may vary in other
implementations consistent with the present invention. Also,
non-dependent acts may be performed in parallel.
[0046] No element, act, or instruction used in the description of
the present application should be construed as critical or
essential to the invention unless explicitly described as such.
Also, as used herein, the article "a" is intended to include one or
more items. Where only one item is intended, the term "one" or
similar language is used. The scope of the invention is defined by
the following claims and their equivalents.
* * * * *