Cross-Reference to Related Applications

The present application claims priority from Australian provisional patent application no. 2010904720 filed 22 October 2011, the contents of which are incorporated herein by reference in their entirety.

Field

The present disclosure relates, generally to the deployment of a reticulated system and, more particularly, to a method of, and equipment for, deploying a reticulated system. The equipment and method have particular, but not necessarily exclusive, application in the field of telecommunications networks. It will be appreciated that the method and the equipment could be used for deploying other reticulated utilities such as electricity, gas or water networks.

Background

When reticulated utilities such as, for example, a telecommunications network is laid in a built-up area, severe disruptions occur due to the need for trenches to be dug etc. Thus, infrastructure is damaged and people are inconvenienced. This can occur for significant periods of time and can result in resentment arising in people affected by the operations. In addition, a large amount of waste is generated which needs to be disposed of and this can cause further disruption and inconvenience.

Summary

In one aspect, there is provided a method of deploying a reticulated system, the method including

forming a microtrench in a substrate, the microtrench having a primary trench and a plurality of secondary trenches branching at spaced intervals from the primary trench;

forming a primary conduit assembly, comprising a conduit and at least one elongate core element contained in the conduit, in a one pass operation past the primary trench;

depositing the primary conduit assembly so formed in the primary trench of the microtrench;

leading a secondary conduit assembly from the primary conduit assembly at at least some of the secondary trenches; and

filling in the microtrench. In this specification, unless the context clearly indicates otherwise, the term "microtrench" is to be understood as a trench in which the conduit assembly fits with minimal lateral clearance. Typically, a width of the microtrench is less than about 100mm, preferably, less than about 70-75mm and, optimally less than about 50mm. The depth of the microtrench may vary depending on the application. The depth of the microtrench may be less than about 500mm and, preferably, may not exceed about 300mm.

The substrate may comprise a roadway and an adjacent sidewalk separated by a kerb and the method may include forming the primary trench of the microtrench on the roadway side of the kerb extending substantially parallel to the kerb. The method may include forming the secondary trenches transversely to the kerb, each secondary trench extending through the kerb and the sidewalk to terminate in a termination pit. The termination pit may be one of two types; a customer access pit or a terminal access pit.

The primary trench may be formed using motorised cutting equipment while the secondary trenches may be cut manually.

The method may include, after formation of the trenches, removing spoil generated as a result of forming the trenches of the microtrench.

The method may include dispensing components of the primary conduit assembly from a dispensing apparatus as the dispensing apparatus is displaced along the primary trench of the microtrench, the method further including placing at least two conduit parts about the at least one core element and securing the parts together to encase the at least one core element in the primary conduit assembly while the dispensing apparatus traverses the primary trench.

By "encase" is meant, unless the context clearly indicates otherwise, that the at least one core element is surrounded by the conduit parts in a longitudinal direction of the primary conduit assembly. Ends of the at least one core element may or may not protrude from the primary conduit

The method may include forming a window in the primary conduit at the location of each of at least some of the secondary trenches so that access can be gained to the at least one core element in the primary conduit assembly at those locations.

The primary conduit assembly may comprise a plurality of core elements and the method may include forming each secondary conduit assembly by accessing at least one of the core elements at each of the locations, drawing the, or each, core element through the window of the primary conduit assembly at that location and forming a secondary conduit about the, or each, core element previously drawn through the window to form the secondary conduit assembly. Further, the method may include forming a joint at a junction between each secondary conduit assembly and the primary conduit assembly to close off the window of the primary conduit assembly at that junction. The joint may be formed by a T - piece placed about the junction, the T-piece comprising two parts which are placed about the junction from opposed sides of the junctions and the two parts being mated together. The T-piece may be radiused for strain-relief purposes.

The method may include terminating a free end of the, or each, core element of the secondary conduit assembly. The free end of the, or each, core element may be terminated with a termination lug prior to placing the free end of the, or each, core element in its associated termination pit.

The method may include placing the conduit assemblies into their associated trenches of the microtrench after formation of the secondary conduit assemblies.

The method may include filling in the trenches using a stabilised sand backfill. The backfill may be a specially formulated stabilised sand mixture that requires no compaction or vibration and will self level. The backfill may have a strength of at least 2MPa to provide similar properties to the substrate.

The method may include capping the filled trenches. Thus, the method may include, at least initially, capping the filled trenches with a temporary cap. The temporary cap may be a reusable cap.

The disclosure extends to a reticulated system deployed using the method as described above.

In a second aspect, there is provided equipment for deploying a reticulated system, the equipment including

microtrenching apparatus for forming at least a primary trench of a microtrench in a substrate, the microtrench having the primary trench and a plurality of secondary trenches branching at spaced intervals from the primary trench;

a conduit assembly dispensing apparatus for forming a primary conduit assembly, comprising a conduit and at least one elongate core element contained in the conduit, in a one pass operation past the primary trench of the microtrench;

secondary conduit components for forming secondary conduit assemblies for placement in at least some of the secondary trenches of the microtrench; and

filling material for filling the microtrench after placement of the primary conduit assembly and the secondary conduit assemblies in the microtrench.

The microtrenching apparatus may include a motorised trench cutter. The trench cutter may also be steerable to follow the roadway in which the primary trench is to be cut The secondary trenches may be cut manually. The dispensing apparatus may comprises a supply of primary component parts, which, in use, are fastened together to form the primary conduit, and a supply of at least one elongate core element receivable in the primary conduit, the primary conduit, after formation, encasing the at least one core element to form the primary conduit assembly. The dispensing apparatus may be configured to form the primary conduit assembly as the dispensing apparatus traverses the primary trench of the microtrench, in use. Further, the dispensing apparatus may include a window forming unit for forming windows in the primary conduit at spaced intervals along the primary conduit.

The secondary conduit components may include a plurality of lengths of secondary conduit in each of which at least one core element extracted from the primary conduit assembly through one of the windows is receivable prior to being placed in one of the secondary trenches of the microtrench.

The equipment may include jointing elements for joining each length of secondary conduit to the primary conduit of the primary conduit assembly in a region of the window from which the secondary conduit extends.

Further, the equipment may include termination lugs for terminating a free end of each core element projecting from a downstream end of its associated length of secondary conduit.

Each secondary trench may terminate in a pit and the equipment may include a receptacle receivable in each pit for lining and closing the pit, the free end of each core element being receivable in one of the receptacles. In case of a telecommunications network, two differently sized pits may be formed depending on the purpose of the pit.

Thus, the equipment may include at least two differently sized receptacles.

The equipment may include spoil removal apparatus for removing spoil arising from formation of the microtrench. The spoil removal apparatus may comprise a vacuum equipped street sweeper for collecting the spoil from the primary trench and each of the secondary trenches of the microtrench.

The filling material may comprise a stabilised sand backfill. The backfill may be a self levelling backfill that requiring minimal, if any, compaction or vibration.

The equipment may include a capping element for capping the microtrench after filling. The capping element may be a temporary, reusable member which is removed prior to being replaced with a permanent cap of material compatible with the substrate in which the microtrench was cut. In the case of a roadway, the permanent cap may be a layer of hot mix bitumen. Brief Description of Drawings

In the drawings,

Fig, I shows a schematic representation of network architecture of a reticulated system deployed in accordance with an embodiment of a method of deploying a reticulated system;

Fig. 2 shows a side view of a step of cutting a primary trench of a microtrench;

Fig, 3 shows a plan view of a first part of the microtrench;

Fig. 4 shows a plan view of a second part of the microtrench;

Fig. 5 shows a sectional side -view of the microtrench taken along line V-V in

Fig. 3;

Fig. 6 shows a sectional side view of the microtrench taken along line VI-VI in

Fig. 4;

Fig. 7 shows a front view of a step of removing spoil after cutting of the microtrench;

Fig. 8 shows, on an enlarged scale, a front view of the part of Fig. 7 encircled by Circle Ά';

Fig. 9 shows a plan view of a step in the method of forming a primary conduit assembly;

Fig. 10 shows a side view of the step of forming the primary conduit assembly;

Fig. 11 shows a front view, on an enlarged, scale of the positioning of the primary conduit assembly after formalion but prior to placement in the primary trench of the microtrench;

Fig. 12 shows an isometric, exploded view of a step of joining a secondary conduit assembly to die primary conduit assembly;

Fig. 13 shows an isometric view of the secondary conduit joined to the primary conduit;

Fig. 14 shows a sectional side view of the placement of the conduit assembly in the microtrench;

Fig. 15 shows a schematic, sectional side view of a pit showing termination of core elements protruding from the second conduit assembly;

Fig. 16 shows, on an enlarged scale, one embodiment of a termination of the core element encircled by Circle 'B' in Fig. 16;

Fig. 17 shows, an exploded view of the termination of Fig. 16;

Fig. 18 shows a side view of another embodiment of a termination of a core element; Fig. 19 shows a schematic, sectional side view of a pit showing a splice at a free end of a core element protruding from the second conduit assembly;

Fig. 20 shows, an enlarged scale, the splice encircled by Circle 'C in Fig. 19;

Fig. 21 shows a part-sectional, side view of a step of filling the microtrench; Fig.22 shows a sectional view of a step of temporarily capping the primary trench of the microtrench after filling;

Fig. 23 shows a sectional side view of a step of removing the temporary cap;

Fig. 24 shows a sectional side view of a step of grinding the substrate prior to permanently capping the primary trench of the filled microtrench; and

Fig. 25 shows a sectional side view of a step of permanently capping the primary trench of the filled microtrench.

Detailed Description of Exemplary Embodiment

Referring initially to Fig. 1 of the drawings, network architecture of a reticulated system is illustrated. The system is designated generally by the reference numeral 10.

The system 10 illustrated is a fibre optic network. More particularly, the system 10 is for providing fibre optic connectivity to a plurality of premises 12.

The system 10 comprises a conduit assembly, or main line, 14 having a primary conduit 16 carrying a plurality of core elements in the form of fibre optic cables 18. In the illustrated embodiment, the fibre optic cables 18 of the main line 14 comprise five single fibre drop cables and two seventy-two fibre local network cables 18.1. The system 10 further includes a plurality of spaced secondary conduits, or drop lines, 20 branching off the main line 14 at regularly spaced intervals.

As illustrated, each drop line 20 services two premises 12. For this purpose, at the location where each drop line 20 branches from the main line 16, two single fibre drop cables 22 from the bundle of cables 18 are drawn out of the main line 14 and terminate in a customer access pit 24. A terminal access pit 26 is arranged at the end of a secondary conduit 20 at each end of each zone of premises.

While the equipment and method will be described with reference to their application to the system 10, i.e. a fibre optic telecommunications network, it will be appreciated that the method and equipment could equally apply to other reticulated utilities such as electricity, gas, water, or the like.

In providing the network to the premises 12, microtrenching is used in order to bury the main line 14 and the drop lines 20. The microtrench comprises a primary or precision trench 28 for the main line 14 and a plurality of drop line trenches 30, branching at longitudinally spaced intervals from the precision trench 28, for the drop lines 20.

Generally, the premises 12 are built alongside a road, indicated by reference numeral 32. The road 32 comprises a roadway 34 with a gutter 36 extending alongside it and a kerb 38 outwardly of the gutter 36. The kerb 38 demarcates the boundary between a sidewalk 40, having a nature strip 42 and a footpath 44, from the roadway 34. In a preferred embodiment, the precision trench 28 is formed in the roadway 34 adjacent, but spaced from, the gutter 36 as shown in greater detail in Figs. 5 and 6 of the drawings. Further, it is to be noted that the roadway 34 comprises a bitumen layer 46 arranged on a concrete layer 48 and a road base 50.

In forming the precision trench 28, cutting equipment 52 (Fig. 2) is used. As illustrated, the cutting equipment includes a prime mover 54 supporting a cutting blade 56 set at the required depth for forming the precision trench 28. In addition, the blade 56 has a width which is sufficient to accommodate the main line 14 in the precision trench 28 with limited clearance. Typically, the width of the precision trench 28 is less than 50mm and, optimally, is about 45mm. It will, however, be appreciated that the width of the precision trench 28 can be selected as desired to accommodate the relevant thickness of main line 14, The blade 56 is set to cut the precision trench 28 to a depth not exceeding about 300mm.

The drop line trenches 30 are formed by cutting manually through the gutter 36, the kerb 38, the nature strip 42 and the footpath 44. The width of the drop line trenches 30 is also selected so that each drop line 20 is snugly accommodated in its associated drop line trenches 30 and to minimise damage to the sidewalk 40.

Further, it will be appreciated that, although it is preferred that the precision trench 28 be formed in the roadway 34 adjacent the gutter 36, if desired or necessary, the precision trench .28 could be formed at any position in the sidewalk 40 itself.

As described above, each drop line trench 20 terminates in a customer access pit 24 or a terminal access pit 26, as the case may be. For ease of forming the pits 24 and 26, an auger (not shown) is used. The auger has a diameter approximating the diameter of the customer access pit 24 which is approximately 350mm. It will be appreciated that customer access pits 24 of larger or smaller diameter can be formed, as desired. The customer access pit 24 is therefore formed by drilling through the sidewalk 40. The customer access pit 24 comprises a receptacle 58 (Figs. 15 and 16). The receptacle 58 has a lid 60. The receptacle 58 is buried in the sidewalk 40 with the lid 60 being accessible, at ground level. To form the terminal access pit 26, the auger forms three spaced holes 62 so that an elongate access pit 26 is formed. An elongate receptacle (not shown) lines the pit and also has a suitable lid to close off access to an interior of the terminal access pit 26,

With reference to the cutting equipment 52 it is to be noted that it is articulated, as at 64, to enable the cutting equipment to follow any curvature of the roadway 3 . In addition, the cutting blade 56 is supported by an hydraulic arm 66 to enable it to be raised and lowered, as desired.

When the precision trench 28 is cut using the cutting equipment 52, spoil 68 is generated as illustrated in Figs. 5 and 6 of the drawings. In addition, in cutting the drop line trenches 30 spoil (not shown) is also generated.

The equipment used to form the network includes a vacuum-equipped street sweeper 70 (Figs. 7 and 8) having sweeping brushes 72. The sweeping brushes 72 sweep up the spoil 68 from opposite sides of the precision trench 28 and draw them into the street sweeper 70. The spoil generated in cutting each drop line trench 30 is collected manually, as illustrated schematically at 74 using a suction pipe 76.

Referring now to Figs. 9-11 of the drawings, the method of forming the primary conduit 14 is described in greater detail. The equipment used embodies a dispensing apparatus in the form of a trailer 78. The trailer 78 has a towbar 80 to enable the trailer 78 to be towed behind a vehicle 82.

As described above, the main line 14 comprises seven fibre optic cables 18.

Two of the cables 18.1 in each bundle are used for feeding the terminal access pits 26 with the remaining five cables 18 being used to service the premises 12 of a node 84 (Fig.1 ). The node 84 is defined as those premises 12 arranged between two terminal access pits 26 and the node 84 is serviced by a group of customer access pits 24. As illustrated in Fig. 1, the node 84 is served by feeding of fibre optic cables 18 from each of two terminal access pits so that a total of twelve premises 12 can be serviced in each node 84.

The main line 14 makes use of two conduit parts being a channel defining part 85 carried on a dispensing reel 86 mounted on the trailer 78 and cover part 87 carried on a dispensing reel 88 of the trailer 78. In addition, the trailer 78 carries seven dispensing reels 90 for dispensing the fibre optic cables 18.

At a trailing end of the trailer 78, the parts 85 and 87 of the conduit 14 and the cables 90 are merged together with the cables 18 being received within the channels of the part 85 and the cover 87 being secured to the part 85 to form the conduit 16 of the main line 14. The conduit 16 encases the fibre optic cables 18 in to form the main line 14. As the vehicle 82 traverses the roadway 34 along the precision trench 28, the main line 14 is formed in a one pass operation and is position adjacent the precision trench 28 as shown in Fig. 11 of the drawings.

Simultaneously with the formation of the main line 14, windows, one of which is shown at 94 in Fig. 12 of the drawings, are formed at spaced intervals in the parts 85, 87 of the conduit 16. The trailer 78 thus includes punches 96 arranged downstream of the dispensing reels 86, 88 for forming the windows 96 in the parts 85, 87 of the conduit 1 .

After the main line 14 has been laid alongside the precision trench 28, the drop lines 20 are formed. This is effected by extracting two of the cables 18 to become the drop line cables 22 for the premises 12 to be serviced by those cables 22. Each pair of drop line cables 22 is encased in a conduit 98 to form the drop line 20.

A joint 100 is formed at the junction between the drop line 20 and the main line 14. The joint 100 comprises a T-piece having a covering portion 102 and a bottom portion 104 which are placed about the main line 14 at the window 94 to close off the window 94. The cover portion 102 is secured to the bottom portion 104 to retain it in position. It is to be noted that the cover portion 102 is radiused for strain relief purposes.

Once all the drop lines 20 have been formed and attached to the main line 14, the assembly so formed is placed in the microtrench comprising the precision trench 28 and the drop line trenches 30. The drop line cables 22 are fed to the customer access pits 24 and the cables 18.1 are fed to the terminal access pits 26. As described above, the customer access pits 24 comprise receptacles 58 in which the drop line cables 22 are stored in a coiled configuration as shown al 106. It is to be noted that each drop line cable 22 is terminated with a pre-termination ferrule 108. The pre-tennination ferrule 108 is encased in hot or cold shrink wrapping 110 to protect the ferrule 108, prior to use.

Fig. 17 shows a first embodiment of a pre-termination ferrule 108, in an exploded view and Fig. 18 shows a second embodiment of a pre-termination ferrule 108.

The drop line cables 22 are generally of sufficient length to reach the premises 12 of the node 84 and are stored within the customer access pit 58 in the coiled configuration 10 until required. If, however, it should transpire that the dropline cables 22 are too short, additional lengths 112 of drop line cables can be spliced to the cables 22 via a splice 1 14. These splices 114 are housed within the customer access pits 58 and are protected prior to use by shrink wrapping 116. Once again, the shrink wrapping 116 can be a hot or cold shrink wrap.

After the main line 14 and the drop lines 20 have been laid, the trenches 28 and 30 are filled. This is accomplished by use of a stabilised sand backfill 118 having a minimum compressive strength of approximately 2 MPa. The backfill 318 is a specially formulated stabilised sand mixture that requires minimal, if any, compaction or vibration and is self levelling. Thus, as shown in Fig. 21 of the drawings, backfill 18 is injected into the precision trench 28 using a grout injection unit 120.

The backfill has the followin formulation:

A similar consistency of backfill 120 is injected, manually, into the drop line trenches 30 to fill the drop line trenches 30.

Once the backfill 118 has been injected into the precision trench 28, the precision trench 28 is capped with a temporary cap 122 which, typically, is of a polymeric material such as rubber. The temporary cap 122 protects users such as cyclists on the roadway 34.

After the backfill 118 has set, the temporary cap 122 is removed as shown at 124 in Fig. 23 of the drawings. After the cap 122 has been removed, a channel 126 is ground into the bitumen layer 46 of the roadway 34. Typically, the channel 126 is of the order of 100 to 200mm wide and, preferably, about 150mm wide. The depth of the channel 126 is generally less than about 50mm and, typically, is about 20 to 30mm. The channel 126 is then filled using a fill of normal hot mix bitumen 128 to complete the installation.

Hence, it is an advantage of the disclosed method and equipment that disruption to surrounding infrastructure is minimised. Also, the use of the terminal access pits 26 and the conduit assembly 14 minimises the need for cable splicing. This renders the installation of the network 10 far more efficient.

The generation of waste is also minimised and any waste is readily and easily collected for responsible disposal. It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the disclosure as shown in the specific embodiments without departing from the scope of the disclosure as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.