UTILITY CHAMBERS AND SURROUNDS AND METHODS THEREFOR

A cover assembly for a utility chamber, comprising a frame with side walls defining a chamber opening and a seating interface, and a cover that closes the opening and seats with the seating interface, a portion of the cover sidewalls profiled to engage with complimentary profiled portions in the frame sidewalls to position and stabilise the cover relative to the frame. The assembly also preferably has a retainer or retainers which engage to secure the cover to the frame. A subsurface utility chamber, comprising a main housing with a base and walls, a frame having a central aperture for chamber access, a cover to close the aperture, and an extension section located between the main housing and the frame, the frame, extension section, and housing releasably and adjustably connected together so as to allow a gap to be established between at least part of the frame and the extension section.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

A frame200and cover100are illustrated inFIGS. 1 and 2. Together, the frame200and cover100form a utility chamber cover assembly. In use, the frame200forms part of the upper section of a utility chamber and defines an opening for accessing the chamber. The cover100is configured to be seated with the frame200to provide a closure for the opening. The frame200and cover100are, in use, held together rigidly and unyieldingly so that when any longitudinal tangential loading is applied to the cover, the cover remains in position relative to the frame. The preferred manner in which this can be achieved is outlined below. However, a person skilled in the art, having read the disclosure below, would realise that there are a number of ways in which the desired result could be achieved by variations of the preferred embodiment.

The frame200is configured to mount to the upper section of the utility chamber. The structure defining the chamber may comprise multiple frame sections (similar to the illustrated embodiment) or may be formed as a unitary frame. In both embodiments the chamber opening is closed by a suitable cover that seats with the top part of the frame defining the opening.

The frame200and cover100are particularly configured for use with a utility chamber that is formed below the surface of a road where high loading forces are anticipated. Such sub-surface chambers may house telecommunications equipment and/or other municipal utilities requiring access for maintenance checks, network expansions or other purposes.

The frame200defines an opening for accessing the sub-surface chamber. The shape and size of the frame200generally reflects a compromise between structural support for load bearing, and the need to provide adequate access to the chamber. The frame200defines a generally rectangular chamber opening.

The frame200generally comprises a seating interface or surface202and a peripheral flange201. The seating interface or surface202of the preferred embodiment is formed from four frame sidewall sections that are connected to form a closed perimeter rectangle (however, it should be noted that the seating interface or surface could be circular, oval, trapezoidal, hexagonal, etc). The seating interface or surface202defines the perimeter of the chamber opening. The flange201is formed as a continuous element that runs around the perimeter of the seating interface or surface202and which extends outwards perpendicularly from the lower edges of the wall sections that form the seating interface or surface202. The flange201has a plurality of regularly spaced fastener apertures that receive complimentary fasteners when the frame200is affixed to a lower frame section during assembly of the chamber structure. A plurality of reinforcing webs204extend between an outer surface of the seating interface or surface202and the upper face of the web201. The reinforcing webs are generally regularly spaced around the perimeter of the seating interface or surface202.

The cover100comprises a plate having a rectangular top surface101sized commensurately with the opening formed by the frame200, and a sidewall102. The sidewall102extends below the top surface101and is generally arranged about the periphery of the plate. The plate is preferably reinforced with webbing located within the confines of the top surface101and sidewalls102as visible inFIGS. 3 to 6. A lattice of webbing is provided below the top surface101of the plate (visible inFIG. 4) in the embodiment shown. It should be noted, however, that the cover sidewalls (and, by extension, the webbing) are not a necessary feature of the cover. The cover assembly could work with a cover that has a retainer adapted to engage with the frame, but no sidewalls.

The cover100is illustrated seated with the frame200inFIG. 2. The frame200receives the cover100so that the cover sidewall102is enclosed by the frame seating interface or surface202. In use, the top surface201of the cover sits substantially flush with the top lip207of the walls that form the seating interface or surface202, the lip207extending about the top of the seating interface or surface202when the cover100is seated.

Complimentary Cover and Frame Profile

The sidewall102of the cover100and the seating interface or surface202or sidewalls202of the frame200are complimentarily profiled. In the illustrated embodiment the frame seating interface or surface202and the cover sidewall102are profiled with a reciprocal surface contour on their inner and outer faces respectfully. The contour is a stepped interface formed into the mating surfaces of the respective components to define a set of complimentary keys and keyways. In use, the keyed profile assists in locating the cover relative to the frame and can, if required, be arranged asymmetrically to facilitate a unique seating orientation. The stepped interface is profiled both in depth and height. That is, height (from top to bottom of the sidewalls), and depth (across the sidewalls). The dimensions of the profiling are chosen so as to best aid in stabilising the cover against longitudinal tangential loading.

The preferred embodiment of frame contour comprises a discontinuous boss that projects inwardly from the seating interface or surface202. The most preferred form of frame boss comprises a series of truncated triangles210that are formed in, and arranged about, an inner face of one or both of the longitudinal sides or frame sidewalls of the seating interface or surface202, and a ledge205that extends inwards from the base of one or both of the transverse sides. The truncated triangles have the appearance of generally trapezoidal shapes formed in relief from the sidewalls. That is, the side edges of the shapes formed in relief in the side walls are angled so that the shapes have the appearance of truncated triangles. The angles of the side walls are chosen so as to maximise the stability of the cover (and the frame) against longitudinal loading. The frame boss is discontinuous at the corners of the frame202where adjacent ones of the longitudinal and transverse frame sidewalls intersect. The cover sidewall102has a complimentary boss that mirrors the boss on the frame200with truncated triangular recesses106on the longitudinal sides and a recessed step105at the base of the transverse sides.

It should be noted that although the most preferred embodiment has the truncated triangles located on one or both of the longitudinal sides, these could be located on the non-longitudinal sides as well as, or instead of, the longitudinal sides. If a non-four-sided shape is used (e.g. a circle or an oval), then one or more of the truncated triangles are located around the perimeter, either evenly spaced or non-evenly spaced. As used in this context, ‘perimeter’ indicates either a continuous sidewall, or a sidewall that is discontinuous around the outside the frame.

It is most preferred that the trapezoidal (truncated triangle) shapes are arranged in the side walls of the frame so that the shorter one of the parallel sides is at or towards the bottom of the frame. The trapezoidal shapes are sized and shaped such that there are two of these shorter sides on two opposed sides of the quadrilateral frame. The two shorter sides correspond to, and are mutually positioned with, cover retainers (described in detail below), the shorter sides also shaped to include a retention interface for receiving at least a portion of the retainer.

The top surfaces of the frame boss define a lip that the cover is seated on. The lip of the frame boss abuts with a complimentary lip on the cover (defined by the cover boss) to support the cover over the chamber and transmits loading on the cover100to the frame200. The load transmitting interface between the illustrated cover100and frame200is therefore determined by the bearing surface area of the respective lips.

Alternate profile and loading arrangements are envisaged. A simple lip and recessed step arrangement (similar to the profile on the transverse sides of the frame200and cover100) may be employed continuously about the respective components to support the cover over the opening. Alternatively, the cover sidewall may be received within a channel in the frame, with the shape of the cover sidewall defining a suitable profile that is mirrored within the channel. The disposition of the cover sidewall and the seating interface or surface of the frame may also be interchanged so that the cover straddles the frame with the sidewall enclosing the seating interface or surface.

However, the preferred form of the profiles of frame200and cover100as shown provides several advantages when applied to subterranean chambers that are subjected to tangential surface loading. Such loading is prevalent in roading applications.

Traffic passing over a subterranean chamber imparts both vertical and tangential force components on the cover. Vertical loading is attributable to the weight force of the vehicle. Tangential loading arises from the friction force between the top surface101of the cover100and the vehicle wheel and is related to the speed with which the vehicle is travelling.

Tangential loading can accelerate frame and cover wear, reducing the longevity of the components and presenting a potential hazard if not compensated for. The angled sidewall interface between the cover100and frame200supports and stabilises the cover against longitudinal tangential loading, reducing rocking and the potential for accidental disengagement. The noise generated by vehicles passing over the chamber is also reduced as the cover is more definitively located.

Ideally the angle of the cover interface is formed so that a reaction force that is normal to the bearing surfaces is produced in load conditions. However, the orientation of the reaction force depends on the mass and speed of the vehicle imparting the load force, and although the interface angle may be selected to reflect anticipated loading, it is unlikely to provide optimal support in all situations. In the preferred embodiment, the sidewall interface is angled at up to approximately 35° from either the horizontal or the vertical.

Cover Retainers

In use, the cover100is engaged with the frame200by seating the cover100in position and actuating four independent retainers120that are spaced about the plate. The retainers120interlock with a complimentary retention interface220on the frame200and urge the cover100and frame200together. The biasing force provided by the retainers further reduces movement of the cover. The retainers engage with the frame to rigidly and/or unyieldingly secure the cover and frame in position relative to one another. The preferred form of the retainers is most clearly illustrated inFIGS. 3 to 6.

Each retainer120includes a rotatable barrel121which has a latch122. The barrel121and latch122are located in an aperture or recess in the cover100, the recesses/apertures disposed generally towards the corners of the cover100. The latch122is formed in a lower extremity of the barrel121. A tool interface123is provided at an upper extremity of the barrel121. The barrel121, latch122and tool interface123are formed as a unitary component in the preferred embodiment.

The barrel121sits within, and is laterally restrained by, a sleeve125. The sleeve125encloses a mid-section of the barrel121between the tool interface123and the latch. The sleeve125and barrel121have complimentary limit stops to restrain upward movement of the barrel. The barrel limit stop124is a circumferential disc-shaped flange that extends about the barrel121adjacent the latch122. The lower face of the sleeve125provides a complimentary limit stop. The respective limit stops provide an upper bound to vertical translation of the barrel121—when the limit stop124contacts the lower face of the sleeve121, it cannot move any further upwards.

The preferred form of sleeve125also incorporates a low friction bushing127. The bushing127is disposed within the sleeve125between an inner surface of the sleeve125and an outer surface of the barrel121to reduce resistance to movement of the barrel121. The sleeve125and the bushing127are interlocked by a complimentary key and keyway so that the bushing127cannot move laterally (i.e. up and down) within and relative to the sleeve125. The bushing127is preferably fabricated from Teflon™ or another suitable low friction material.

The upper extremity of the sleeve125terminates in a circumferential disc126which extends outwards perpendicular to the lower or main part of the sleeve125. A retainer cap130is arranged coaxially above the barrel121and sleeve125. The retainer cap130is generally cylindrical and hollow, and sit within the aperture or recess in the cover100. In use, the upper surface of the disc126abuts with the lower surface of the retainer cap130. The preferred form of the disc126includes a circumferential rebate formed about the perimeter of the upper surface. The rebate is generally commensurate with a lower internal edge of the retainer cap130, so that the sleeve125and retention cap130can be mutually interlocked by an interference fit that laterally restrains the sleeve125and barrel121with respect to the retainer cap130. The retainer cap130and sleeve125may alternatively be fabricated as a unitary component.

The hollow cylindrical retainer cap130defines an open ended cavity that houses the barrel tool interface123. The upper end of the retainer cap130terminates in an opening adjacent the plate top surface101. The opening provides access through the top surface101to the barrel121. The open end of the of the retainer cap130may be sheathed with a removable lid (not shown in the figures) to reduce runoff of surface water into the cavity. The most preferred form of retainer cap130has an upper flange that in use rests against the top surface of the plate100to hold the cap130in position—to stop the cap130passing through the cover100. The preferred form of the cover100can be recessed around the aperture or recess to produce a roughly flat upper surface across the top of the cover100.

The upper opening of the retainer cap is generally circular. Two placement lugs131project inwardly from opposed sides of the opening perimeter. The lugs131are generally symmetric in shape, and are disposed symmetrically about the opening—i.e. on directly opposite sides of the opening. Each of the lugs131extends around a section of the opening perimeter along an arc or portion of the perimeter of the opening.

The barrel121is biased upward toward retainer cap130and top surface101of the plate by a biasing spring135. The biasing spring135is disposed below the barrel121and takes the form of a leaf spring. The biasing spring135is supported by a portion or support face136of the cover100, the cover100shaped to include the support face136. Each one of the retainers has an equivalent individual biasing spring. Part of the upper surface of the biasing spiring135presses against the lower end of the barrel121in use and pushes the barrel121upwards.

The cover100must be adequately seated with the frame200before the retainers120can be actuated to secure the cover100in position. When the cover100is seated, the base of each retainer120is situated adjacent a complimentary retention interface220in the frame200, as shown inFIG. 6. The retention interface220provides a compatible ledge for the latch122to slot under and engage with to interlock the cover100with the frame200. The preferred form of retention interface is a cut-out section220in the frame sidewall, the cut-out section close to the latch122portion of the retainer when the cover is in position in use, the outer end portion of the latch rotating into the cut-out section so that the upper surface of the latch contacts the downwards-facing surface of the cut-out section. Preferably there are four cut-out sections, two on each of the longitudinal sidewalls of the frame, close to the corners of the frame.

To actuate each retainer120, the barrel121is depressed against the biasing force of the leaf spring135and rotated a quarter turn. Depressing the barrel121provides clearance between the latch122and the retention interface220, allowing the latch121to move without interference with the frame200. The latch122is rotated from a disengaged position (aligned longitudinally with the plate), to an engaged position (transverse to the plate), where the latch122slots underneath the ledge220to engage the cover100with the frame200.

The depressing force can be removed from the barrel when the latch121is positioned under the ledge220. The removal of the depressing force causes the biasing force of the leaf spring135to be transmitted through the barrel121, to the latch121, to the retention interface220. This has the overall effect of urging the cover100toward the frame200and securely interlocking the cover100in position.

Similarly, the barrel121must be depressed by a depressing force on the cover100before the retainers120can be disengaged. Disengagement is achieved by rotating the barrel121through a quarter turn in the reverse direction to that used to engage or actuate the retainers. The biasing spring135retains the barrel limit stop124against the retainer sleeve125when the retainer120is disengaged and when there are no external forces acting on the barrel121.

The biased retention mechanism further reduces play between the components during dynamic loading and helps to impede unauthorised removal of the cover.

Retainer Actuation Tool

A first embodiment of a tool for actuating the retainers120is illustrated inFIGS. 6 to 10. The tool300has a staggered actuation mechanism that is deployed over two distinct phases. The lower end of the tool300is illustrated inFIG. 6, clear of the upper opening of the retainer120, and ready for insertion into the top opening of the retainer120. The actuation mechanism305is orientated for insertion into one of the retainer openings.

The actuation mechanism305comprises a lower section of the tool300, and includes an outer stem330that has a pair of channel lugs331extending perpendicularly from the outer stem330, the lugs331opposed circumferentially and positioned adjacent a lower extremity of the outer stem330. The lugs331define the discontinuous lower lip of a circumferential channel332which runs between an upper lip334and the discontinuous lower lip defined by the lugs331. The upper lip334of the channel332is spaced from the lower lip by an offset commensurate with the thickness of the placement lugs131of the retainer cap130.

Similarly to the arrangement of the placement lugs131about the retainer cap130opening, the channel lugs331are disposed symmetrically about the tool stem330. The arc length of the channel lugs331is roughly equivalent to the arc length of the placement lugs131, with the respective lugs each spanning less than a quarter of a circle to provide a complimentary gap for the reciprocal lugs to fit between when the tool300is inserted into the retainer cap130opening.

The depth to which the tool300can be inserted into the retainer cap130is set by the position of the upper lip334. Abutment of the upper channel lip334with the placement lugs131prevents further insertion of the tool300into the retainer cap130and defines the distance between the tool head323and the tool interface123on the barrel121. Following insertion of the tool300, the actuation mechanism305is interlocked with the retainer cap130by rotating the tool stem330through half a turn so that the channel lugs331become generally aligned below the placement lugs131. Aligning the respective lugs locates and secures the tool in position, as illustrated inFIG. 8.

The tool head323is disposed on the lower end of an extensible shaft320that is housed within the stem300. The shaft320is shown in an extended position from the stem330inFIG. 7and retracted within the stem inFIG. 6. The stem320and shaft320are arranged concentrically. The shaft320is extended from the stem330and the tool head323engaged with the tool interface123on the barrel121by partially depressing the actuation lever301—i.e. towards the plate100from the position shown inFIG. 6. Further depression of the actuation lever subsequent to engagement of the tool head323with the tool interface123is opposed by the biasing spring135.

The tool300may utilise hydraulic or pneumatic assistance to offset the biasing force of the leaf spring135. As shown inFIG. 8, a pneumatic canister306is engaged with the tool300in the illustrated embodiment. The canister306and associated pneumatic system in the actuation mechanism305supplies the driving force to depress the shaft320against the biasing force of the leaf spring330. The tool is located and translationally restrained during actuation of the retainer120by the interlocking channel332and placement lugs131.

The illustrated tool head323and tool interface123comprise complimentary driving faces disposed on opposing sides of the tool head323and barrel121respectively. The illustrated driving faces are reciprocal flatted sections defined by a chord intersecting the respective cylinders on opposed side. The symmetrical flats permit the tool head323to impart a torque to the tool interface123and drive the barrel112and latch122rotationally. The latch122is rotated by manually rotating the actuation lever301through a quarter turn as illustrated inFIGS. 8 to 10.

A second embodiment of tool is shown inFIGS. 25a-c. The lower end of the tool is the same as or very similar to that described above for the first embodiment above. In a similar manner to that described above, following insertion of the tool, the actuation mechanism is interlocked with the retainer cap by rotating the tool stem through half a turn so that the channel lugs become generally aligned below the placement lugs. Aligning the respective lugs locates and secures the tool in position. The rotation of the tool stem in the second embodiment is achieved by means of rotation of two manual actuation levers1000located generally on opposed sides of the tool stem so that the levers can be gripped and the tool stem rotated.

In a similar manner to the first embodiment, the tool head is disposed on the lower end of an extensible shaft that is housed within the stem, the stem and shaft arranged concentrically. In this second embodiment, the stem is engaged with the cover so that it is fixed in position relative to the cover vertically.

A lever1001extends from the top of the lower end of the tool. The lever can be moved between a disengaged position where the lever is at an angle or horizontal/perpendicular to the lower part of the tool, and the shaft is in an upwards position, to and upright, engaged or vertical position. As the lever1001is moved to wards the vertical position, the lower end of the lever presses down on the top of the shaft, which is pushed down against the spring to disengage the spring from the latch so that the lever can be rotated in the vertical using the handle1002to unlock the cover latch.

The foregoing description of the invention includes preferred forms thereof. Modifications may be made thereto without departing from the scope of the invention.

It should also be noted that directional terms such as ‘upwards’, ‘downwards’ ‘upper’, etc have been used in this specification. It is to be noted that these terms are used in relation to an ‘in use’ state where the upper surface of the cover is aligned substantially horizontally. It is, of course, not necessary that the chamber cover assembly system described above be used in this orientation—it could be used rotated through up to 90 degrees or more onto it's side, or even upside-down (rotated through up to 180 degrees) if required. The directional terms are used as indicative terms only and are not intended to limit the use to one specific or even general orientation.

An alternative jointing or utility chamber1is shown inFIG. 11. The chamber1has three main parts: a main housing20, a frame3which in use forms the upper part of a utility chamber, and provides or defines the opening thereto and communicates to the utility chamber below, and a removable hatch4which closes the opening in use.

Frame

As shown inFIGS. 12aand12b, the frame3has a generally rectangular outline when viewed in plan, with a central opening or aperture5that passes through from the upper surface18of the surround of the frame3. When the frame is installed the aperture2allows access to the inside of the utility chamber located below.

In cross-section, each of the four sides of the frame1has the shape of an inverted U or channel, as shown inFIG. 14. The base portion defining the base of the inverted U channel is preferably flat and defines the upper surface18and surround of the frame1. The sides of the U form two walls that extend or depend downwards from the surround when the frame1is aligned for use. The two walls are an inner wall7that runs around the inner edge central aperture2, and an outer wall6that bounds the outer edge of the upper surface18.

In the preferred form the outer wall6depends from the outer edge of the upper surface18. The inner wall7may extend all the way down, or as shown may extend partially down before it steps or flanges inwards to form a hatch lip11. The hatch lip11then has an extension or leg as shown that extends further downwards to present a downwardly directed bearing surface. The hatch lip11runs around a lower edge of the inner wall7, projecting inwards from the aperture2to provide an upward facing hatch support surface.

In the preferred form, holes pass through the hatch lip11, spaced at intervals around the periphery of the hatch lip11. Typically, in the preferred embodiment, there are four holes, two on each of the longer sides of the hatch lip11, positioned in pairs opposite each other. That is, the positions of the holes on one side correspond to the position of the holes4on the opposite. In alternative embodiments, the holes can be replaced by cutouts or notches if preferred.

In the preferred embodiment shown the hatch lip11is continuous about the central aperture2. However in other embodiments the hatch lip11may be only present where needed e.g. for holes and for supporting the hatch4.

The hollow central part of the frame3is divided into compartments by webs, spaced at intervals and running between the inner and outer walls6,7. These run perpendicular to the inner and outer walls except at the corners of the frame, where four of the webs run diagonally from the inner corners to the outer corners. The function of the webs is two-fold. The first of these is to impart strength to the frame1. The second is to form part of a downwardly directed bearing surface.

In the preferred embodiment each of the webs join the outer and inner walls respectively. However in other embodiments where strength is not required so much as sufficient bearing surface they may join to one or two of the walls.

The inner and outer walls and the webs all extend so far to present a co-planar single or multiple surface that presents as a downwardly directed bearing surface10.

The frame3(and hatch4) are usually formed from a metal material e.g. die cast, cast or moulded aluminium, cast iron or steel. This can become slippery when wet, an undesirable characteristic for surfaces that require traction, e.g. road or foot traffic surfaces. Although as stated above, the inner and outer walls in one embodiment do not overlap above the upper surface, in another embodiment they can. The result is that the central part of the frame (the ‘underside’ of the u-shape) is recessed to form a shallow depression. The recessed area can therefore be filled with material that will increase the amount of grip on the uppermost surface—e.g. a thin layer of tarmac, paving or other grip enhancing material. Alternatively, a thin layer of textured rubber matting, resin or similar could be disposed in the recessed area. The recessed area may alternatively be textured to provide sufficient grip e.g. raised stipples or similar. This stippling may also provide a keying to any material that is located in the recessed area.

The hatch4may also be recessed to receive a similar surface treatment.

The hatch4and frame1may be coloured also if desired either directly by the material of their construction or by application of secondary materials, e.g. paints, resins, coloured finishes (including concretious surface finishes).

The hatch4is sized to fit the aperture2, with the edges of the hatch4resting on the lip11.

Hatch

The hatch4is preferably formed as a single planar panel, strengthened on its underside by a number of flanges, aligned perpendicular to the under surface of the hatch, so that they face vertically downwards when the hatch4is in position. A number of these flanges are aligned running lengthways and crossways across the underside of the hatch, parallel and perpendicular to each other, as shown.

Main Housing

As shown inFIGS. 15,16, and17, the preferred embodiment of main housing is formed from a base, two long side walls connected at their lower edges to the base so that they are both vertical and aligned perpendicular to the base, the two walls substantially parallel to one another, and two shorter side walls which connect between the longer side walls. The two shorter side walls and the two longer side walls all have a top flange, generally numbered as100on all four of the walls, which extends horizontally outwards from the top of the wall. When the walls are connected, from above, the flange has the appearance of a continuous unbroken loop. The walls are connected so that the flange is located at the same height all the way around the closed perimeter. The two shorter walls, which are located opposite each other in the preferred form, have a lower edge which is located some way above the base of the main housing when the shorter walls are connected to the longer walls, so that apertures are formed at each end to allow cables, pipes or similar to be routed to pass through the chamber.

In use, the frame3is placed on top of the main housing20, with the lower bearing surfaces10in direct contact with the upper flange100of the main housing. The frame and the main housing are connected together. This connection is achieved using a connection mechanism. In the preferred embodiment this mechanism is threaded bolts which pass though complimentarily aligned holes in the frame and housing, with nuts screwed onto the threaded bolts to clamp the frame and housing together. These threaded bolts and nuts, and the corresponding apertures in the frame and housing, are shown generally as items200inFIGS. 11 and 19. Detail of the connection mechanism is shown in the breakout box ofFIG. 20.

Method of Installation

The method of installation of the utility chamber1will now be described. This method will firstly be described in relation to installation in ground with a horizontal surface, and with the assumption that the upper surface of the chamber can be aligned substantially with the surface of the ground without excessive difficulty. Firstly, a void, cavity, pit or hole is created. This receives and supports and holds the utility chamber1. The base of the hole is formed from compacted bedding of sand, blue chip or similar, with a nominal depth of 200 mm. However, this bedding depth is adjusted to ensure that the chamber base is accommodated at the right height so that the cover matches the finished ground level. The main housing20is placed into the pit pre-assembled, or is assembled in situ.

The frame is then placed on top of the housing, so that as stated above, when the frame is placed on top of the main housing, it's upper surface will be level with the surface of the ground. The lower bearing surfaces of the frame rest directly onto the flange100of the main housing.

The main housing and the frame are then connected together using the connection mechanism200.

Once the main housing is in place, the gap between the walls of the hole and the outer surfaces of the walls of the housing is filled with compacted backfill150, up to a point at or close to the upper surface of the frame. As shown inFIG. 19, a layer of tarmac surfacing300, pavers400or similar can be added, this serving to align the plane of the top surface of the frame with the surface of the ground.

As shown in the breakout boxes onFIGS. 11 and 19, the frame rest directly on the housing, so that there is no gap between the upper surface of the flange100on the housing, and the lower bearing surfaces of the frame.

Optional Extras

Optional extras which can be used with the chamber include a cable management bracket500such as the one shown inFIG. 21, which is connected to one wall to assist in managing lengths of cable, and a cable protection plate501, which can be used to shield the cable from items descending from above.

Variants

Height Extension

It can be seen that the preferred embodiment of the invention described above is most useful when the upper surface of the ground is level and is unlikely to change. However, the level of road surfaces can change, for example as further layers of bitumen or tarmac are added. Also, the chambers are a standard depth, which may be too little if, for some reason, a deeper hole than usual is required.

FIGS. 22 and 23show detail of a extension section560that can be used with the chamber of the present invention. The extension section560is located between the main housing and the frame to raise the level of the frame. The extension is formed from four wall sections561, as shown inFIG. 23a. Each of the wall sections561has a lower flange562and an upper flange563. In use, the wall sections that form the extension section560are placed on top of the main housing so that the lower flanges562sit flush with the flange100of the main housing. The frame is then place on top of the extension section so that the lower bearing surfaces of the frame rest against the upper flange563. The connection mechanism described above can be used to connect the frame the extension and the housing together, by passing threaded bolts through holes in each of the members, the holes aligned linearly to allow the passage of the bolts, and then tightening nuts onto the bolts, the nuts located at appropriate positions along the length of the bolts. The overall effect is to raise the level of the upper surface of the frame by the height of the extension560.

Sloped Surface

If the level of the surface into which the chamber is going to be located is sloped rather than level, then a variation of the present invention can be used to ensure that the upper surface (i.e. the outer part of the frame and the hatch) conforms to the ground slope. This is described below.

The base/main housing are located into the hole in the same or similar manner to that outlined above for the level ground installation, with the top flange of the housing below the surface of the ground at all points.

The frame is then positioned over the housing. In this variant, as shown inFIG. 23, the frame is positioned with its lower surface (which in the level ground embodiment was in contact with the upper surface of the flange) clear of the upper surface of the flange. The frame is held in position by adjustment of the connection mechanism—in the preferred embodiment by adjusting the location of the nuts on the threaded bolts so the frame rests (on the nuts) at an angle relative to the housing. The frame is not required to be out of contact with the housing at all points. It may contact the housing e.g. at a corner or edge. However, as the frame and the housing will be aligned at different angles, there will be gaps most of the way around the perimeter. The angle of the frame is adjusted so that it is parallel to the surface of the surrounding ground. As shown inFIG. 24, concrete shuttering is positioned inside the frame and housing, to prevent concrete from entering the interior of the housing through the gaps.

In this embodiment, a countersunk edge trench has been dug around the top part of the hole before the housing and frame are located into the hole. Therefore, there is a gap between the outer edges of the walls of the frame and the upper part of the walls of the housing. Concrete is poured into this gap to form a concrete collar around the frame and the upper part of the housing. In the most preferred embodiment, a reinforcing hanger is connected to, and extends outwardly from, the frame, so that it is located in the trench and will be covered by the concrete once poured. The hanger holds two rings of reinforcing steel rods, the rods forming a substantially continuous ring around the perimeter of the frame, the two rings having slightly different sizes so that they are located at slightly different distances from the frame, around the frame. The ring may not actually be continuous or unbroken—it may have gaps e.g. at the corners, and when a substantially unbroken or continuous ring is referred to, it should be taken to include a ring which has at least one or more small gaps. The reinforcing hanger and the associated rods are optional.

It should be noted that different sizes and shapes of chamber and frame other than those described and shown could be utilised. For example square, circular or oval or other shaped frames could be used without departing from the inventive concept described and claimed.

The foregoing description of the invention includes preferred forms thereof. Modifications may be made thereto without departing from the scope of the invention.