Title:
TEMPORARY COVER ASSEMBLY FOR A VOID
Kind Code:
A1


Abstract:
A temporary cover assembly for a void comprising a cover plate 209 configured to close an opening in the void and means 201, 202, 207 to releasably attach the cover plate 209 to a cover slab 105 of the void.



Inventors:
Auckland, Paul Richard (Nottinghamshire, GB)
Application Number:
11/744486
Publication Date:
12/13/2007
Filing Date:
05/04/2007
Primary Class:
International Classes:
E02D29/14
View Patent Images:
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Primary Examiner:
ADDIE, RAYMOND W
Attorney, Agent or Firm:
Ekstrom Law Group (Santa Fe, NM, US)
Claims:
What is claimed is:

1. 1.-28. (canceled)

29. A temporary cover assembly for a void comprising: a cover plate configured to close an opening in said void; means to releasably attach said cover plate to a cover slab of said void; wherein said means to attach said cover plate comprises: a first bracket; and a second bracket; means to releasably attach said first bracket and said second bracket to said cover slab; and means to releasably attach said cover plate to said first bracket and said second bracket.

30. A temporary cover assembly according to claim 1 wherein said means to releasably attach said first bracket and said second bracket to said cover slab comprises at least one extendible trench strut.

31. A temporary cover assembly according to claim 1 wherein said means to releasably attach said first bracket and said second bracket to said cover slab further comprises a first protrusion on said first bracket and a second protrusion on said second bracket; and said protrusions are configured to be located, in use, on an upper surface of said cover slab.

32. A temporary cover assembly according to claim 1 wherein said means to releasably attach said cover plate to said first bracket and said second bracket comprises: a first bracket upper shelf, extending laterally from a surface of said first bracket; and a second bracket upper shelf, extending laterally from a surface of said second bracket; wherein said cover plate is configured to be located on and extend between said first bracket upper shelf and said second bracket upper shelf.

33. A temporary cover assembly according to claim 1 further comprising means to releasably attach said cover plate to said first bracket and said second bracket, the assembly comprising: a first bracket upper shelf, extending laterally from a surface of said first bracket; and a second bracket upper shelf, extending laterally from a surface of said second bracket; and, in which said cover plate is configured to be located on and extend between said first bracket upper shelf and said second bracket upper shelf; wherein the assembly further comprises a spacer configured to be disposed between said first bracket upper shelf and said cover plate, said spacer also configured to be disposed between said second bracket upper shelf and said cover plate.

34. A temporary cover assembly according to claim 1 further comprising means to releasably attach said cover plate to said first bracket and said second bracket, the assembly comprising: a first bracket upper shelf, extending laterally from a surface of said first bracket; and a second bracket upper shelf, extending laterally from a surface of said second bracket; wherein said cover plate is configured to be located on and extend between said first bracket upper shelf and said second bracket upper shelf; and in which said cover plate comprises: a first cover plate section; and a second cover plate section.

35. A temporary cover assembly according to claim 1 comprising means to releasably attach said cover plate to said first bracket and said second bracket, the assembly comprising: a first bracket upper shelf, extending laterally from a surface of said first bracket; and a second bracket upper shelf, extending laterally from a surface of said second bracket; wherein said cover plate is configured to be located on and extend between said first bracket upper shelf and said second bracket upper shelf; and the assembly further comprising first locking means configured to lock said cover plate to said first bracket upper shelf.

36. A temporary cover assembly according to claim 1 comprising means to releasably attach said cover plate to said first bracket and said second bracket, the assembly comprising: a first bracket upper shelf, extending laterally from a surface of said first bracket; and a second bracket upper shelf, extending laterally from a surface of said second bracket; wherein said cover plate is configured to be located on and extend between said first bracket upper shelf and said second bracket upper shelf; the assembly further comprising second locking means configured to lock said cover plate to said second bracket upper shelf.

37. A temporary cover assembly according to claim 1 comprising means to releasably attach said cover plate to said first bracket and said second bracket, the assembly comprising: a first bracket upper shelf, extending laterally from a surface of said first bracket; and a second bracket upper shelf, extending laterally from a surface of said second bracket; wherein said cover plate is configured to be located on and extend between said first bracket upper shelf and said second bracket upper shelf; in which the cover plate comprises: a first cover plate section; and a second cover plate section; and the assembly further comprising third locking means configured to releasably lock said first cover plate section and said second cover plate section together.

38. A temporary cover assembly according to claim 1 comprising means to releasably attach said cover plate to said first bracket and said second bracket, the assembly comprising: a first bracket upper shelf, extending laterally from a surface of said first bracket; and a second bracket upper shelf, extending laterally from a surface of said second bracket; wherein said cover plate is configured to be located on and extend between said first bracket upper shelf and said second bracket upper shelf; the assembly further comprising locking means to lock said cover plate to said first bracket upper shelf and/or said cover plate to said second bracket upper shelf and/or a first cover plate section to a second cover plate section, and in which the assembly comprises identification means configured to allow a user to identify the or each locking means.

39. A temporary cover assembly according to claim 1 comprising: a vessel configured to be located above said cover plate, said vessel configured to restrict unwanted matter from falling on said cover plate.

40. A method of attaching a temporary cover assembly to a manhole comprising: providing a cover plate configured to close an opening in said manhole; releasably attaching said cover plate to a cover slab of said manhole; wherein said step of releasably attaching said cover plate to a cover slab of said manhole comprises: releasably attaching a first bracket and a second bracket to said cover slab; and releasably attaching said cover plate to said first bracket and said second bracket.

41. A method of attaching a temporary cover assembly to a manhole according to claim 40 comprising: releasably attaching said first bracket and said second bracket to said cover slab with at least one extendible trench strut.

42. A method of attaching a temporary cover assembly to a manhole according to claim 12 comprising: locating a first protrusion extending from said first bracket on an upper surface of said cover slab; and locating a second protrusion extending from said second bracket on an upper surface of said cover slab.

43. A method of attaching a temporary cover assembly to a manhole according to claim 40 comprising: locating said cover plate on a first bracket upper shelf, said first bracket upper shelf extending laterally from a surface of said first bracket; and locating said cover plate on a second bracket upper shelf, said second bracket upper shelf extending laterally from a surface of said second bracket.

44. A method of attaching a temporary cover assembly to a manhole according to claim 40 comprising: locating said cover plate on a first bracket upper shelf, said first bracket upper shelf extending laterally from a surface of said first bracket; and locating said cover plate on a second bracket upper shelf, said second bracket upper shelf extending laterally from a surface of said second bracket; the method further comprising: disposing a spacer between said first bracket upper shelf and said cover plate, and disposing said spacer between said second bracket upper shelf and said cover plate.

45. A method of attaching a temporary cover assembly to a manhole according to claim 40 comprising: locating said cover plate on a first bracket upper shelf, said first bracket upper shelf extending laterally from a surface of said first bracket; and locating said cover plate on a second bracket upper shelf, said second bracket upper shelf extending laterally from a surface of said second bracket, and wherein said cover plate comprises: a first cover plate section; and a second cover plate section.

46. A method of attaching a temporary cover assembly to a manhole according to claim 40 comprising: locating said cover plate on a first bracket upper shelf, said first bracket upper shelf extending laterally from a surface of said first bracket; and locating said cover plate on a second bracket upper shelf, said second bracket upper shelf extending laterally from a surface of said second bracket; the method further comprising locking said cover plate to said first bracket upper shelf using first locking means.

47. A method of attaching a temporary cover assembly to a manhole according to claim 40 comprising: locating said cover plate on a first bracket upper shelf, said first bracket upper shelf extending laterally from a surface of said first bracket; and locating said cover plate on a second bracket upper shelf, said second bracket upper shelf extending laterally from a surface of said second bracket; and the method further comprising locking said cover plate to said second bracket upper shelf using second locking means.

48. A method of attaching a temporary cover assembly to a manhole according to claim 40 comprising: locating said cover plate on a first bracket upper shelf, said first bracket upper shelf extending laterally from a surface of said first bracket; and locating said cover plate on a second bracket upper shelf, said second bracket upper shelf extending laterally from a surface of said second bracket; wherein said cover plate comprises: a first cover plate section; and a second cover plate section; and the method further comprising locking said first cover plate section and said second cover plate section together using third locking means.

49. A method of attaching a temporary cover assembly to a manhole according to claim 40 comprising: locating said cover plate on a first bracket upper shelf, said first bracket upper shelf extending laterally from a surface of said first bracket; and locating said cover plate on a second bracket upper shelf, said second bracket upper shelf extending laterally from a surface of said second bracket; and the method further comprising: locking said cover plate to said first bracket upper shelf using first locking means, and/or locking said cover plate to said second bracket upper shelf using second locking means, and/or locking a first cover plate section to a second cover plate section using third locking means; wherein the method comprises identifying each locking means using identification means.

50. A method of attaching a temporary cover assembly to a manhole according to claim 40 comprising: locating said cover plate on a first bracket upper shelf, said first bracket upper shelf extending laterally from a surface of said first bracket; and locating said cover plate on a second bracket upper shelf, said second bracket upper shelf extending laterally from a surface of said second bracket; the method further comprising: locating a vessel above said cover plate, said vessel configured to restrict unwanted matter from falling on said cover plate.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to International Application No. PCT/GB2005/003598 filed on 19 Sep. 2005 and published as International Publication No. WO 2006/048593 A1, which, in turn, claims priority from Patent Application No. GB 0424390.3 filed on 4 Nov. 2004 and Patent Application No. GB 0425210.2 filed on 16 Nov. 2004, each of which is hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to covers for voids, and in particular to temporary cover assemblies for voids.

BACKGROUND TO THE INVENTION

Uncovered voids can be very dangerous, particularly in areas where personnel are working. Uncovered voids may include voids such as unfinished manholes, unfinished gullies, or any type of hole in a surface. If uncovered voids are not properly covered or marked, then personnel can easily fall into them, causing injury or death to themselves.

Manholes, sometimes referred to as inspection chambers, are used to allow personnel to inspect underground structures such as sewers or pipelines used for carrying water and so on. The manhole is an access hole in a ground surface that can allow personnel to enter the underground structure.

Referring to FIG. 1 herein, there is illustrated a typical prior art manhole shown in cross-section. The manhole 101 comprises a manhole ring 102, a cover slab 103, brickwork 104 and a cover 105. For deep manholes, steps 106 may also be provided.

The cover slab 103 is usually formed from a concrete biscuit, and is positioned on the manhole ring 102. The cover slab 103 comprises a gap substantially in its centre to allow access to the manhole ring 102. The manhole ring 102 provides a secure conduit through which personnel can enter or inspect the underground structure. Brickwork 104 is laid on top of the cover slab 103. In FIG. 1, there is shown two courses of bricks. In the UK, the brickwork should comprise between two and four courses of bricks. A metal manhole cover 105 is located on the brickwork 104 to seal the manhole when it is not in use.

On a new building site, where a manhole is being constructed, the manhole ring 102 is laid first. The cover slab 103 is then laid on top of the manhole ring 102.

The next stage of construction is for a brick layer to lay the brickwork 104 on top of the cover slab 103. This is a dangerous operation, because the bricklayer is kneeling over an open manhole which could comprise a long drop, and could be providing open access to a sewer that comprises foul gases. There is therefore a risk of injury to the bricklayer whilst he is laying the brickwork 104.

Furthermore, when a bricklayer is laying the brickwork he may be careless and allow excess mortar to drop down into the manhole. This could remain on the surface of the manhole ring or in the underground structure, which would not be desirable.

Once the brickwork 104 has been laid, it may be required to be left overnight as the mortar used to affix the brickwork dries and sets. Under these circumstances, the manhole is usually covered over with a piece of plywood. It is possible that the plywood could be accidentally moved thereby leaving an open manhole. It is also possible that the plywood could be damaged by vehicles working on site accidentally driving over the manholes. There is therefore an increased risk of injury for personnel on the building site.

A further problem with constructing manholes is that building sites are usually extremely muddy, and mud and silt can enter the manhole during construction. Once the manhole has been constructed, a further operation is required to remove the mud and silt from the manhole and from the underground structure to which the manhole allows access. This operation is time consuming, expensive and dangerous.

SUMMARY OF THE INVENTION

According to a first aspect there is provided a temporary cover assembly for a void comprising: a cover plate configured to close an opening in the void; means to releasably attach the cover plate to a cover slab of the void, wherein the means to attach the cover plate comprises: a first bracket; a second bracket; means to releasably attach the first bracket and the second bracket to the cover slab; and means to releasably attach the cover plate to the first bracket and the second bracket.

Preferably, the means to releasably attach the first bracket and the second bracket to the cover slab comprises at least one extendible trench strut.

Preferably, the means to releasably attach the first bracket and the second bracket to the cover slab comprises a first protrusion on the first bracket and a first protrusion on the second bracket; and the protrusions are configured to be located, in use, on an upper surface of the cover slab.

Preferably, the means to releasably attach the cover plate to the first bracket and the second bracket comprises: a first bracket upper shelf, extending laterally from a surface of the first bracket; a second bracket upper shelf, extending laterally from a surface of the second bracket; wherein the cover plate is configured to be located on and extend between the first bracket upper shelf and the second bracket upper shelf.

Preferably, the temporary cover assembly comprises a spacer configured to be disposed between the first bracket upper shelf and the cover plate, the spacer also configured to be disposed between the second bracket upper shelf and the cover plate.

Preferably, the cover plate comprises: a first cover plate section; and a second cover plate section.

Preferably, the temporary cover assembly comprises: first locking means configured to lock the cover plate to the first bracket upper shelf.

Preferably, the temporary cover assembly comprises: second locking means configured to lock the cover plate to the second bracket upper shelf.

Preferably, the temporary cover assembly comprises: third locking means configured to releasably lock the first cover plate section and the second cover plate section together.

Preferably, any of the first, second or third locking means comprises any of the following: padlock or combination lock

Preferably, the temporary cover assembly comprises: first identification means configured to allow a user to identify the first locking means.

Preferably, the temporary cover assembly comprises: second identification means configured to allow a user to identify the second locking means.

Preferably, the temporary cover assembly comprises: third identification means configured to allow a user to identify the third locking means.

Preferably, the temporary cover assembly comprises: a vessel configured to be located above the cover plate, the vessel configured to restrict unwanted matter from falling on the cover plate.

According to a second aspect, there is provided a method of attaching a temporary cover assembly to a void comprising: providing a cover plate configured to close an opening in the void; releasably attaching the cover plate to a cover slab of the void, wherein said step of releasably attaching said cover plate to a cover slab of said manhole comprises: releasably attaching a first bracket and a second bracket to the cover slab; and releasably attaching the cover plate to the first bracket and the second bracket.

Preferably, the method comprises: releasably attaching the first bracket and the second bracket to the cover slab with at least one extendible trench strut.

Preferably, the method comprises: locating a first protrusion extending from the first bracket on an upper surface of the cover slab; and locating a second protrusion extending from the second bracket on an upper surface of the cover slab.

Preferably, the method comprises: locating the cover plate on a first bracket upper shelf, the first bracket upper shelf extending laterally from a surface of the first bracket; and locating the cover plate on a second bracket upper shelf, the second bracket upper shelf extending laterally from a surface of the second bracket.

Preferably, the method comprises: disposing a spacer between the first bracket upper shelf and the cover plate, and disposing the spacer between the second bracket upper shelf and the cover plate.

Preferably, the cover plate comprises: a first cover plate section; and a second cover plate section.

Preferably, the method comprises: locking the cover plate to the first bracket upper shelf using first locking means.

Preferably, the method comprises: locking the cover plate to the second bracket upper shelf using second locking means.

Preferably, the method comprises: locking the first cover plate section and the second cover plate section together using third locking means.

Preferably any of the first, second or third locking means comprises any of the following: padlock or combination lock.

Preferably, the method comprises: identifying the first locking means using first identification means.

Preferably, the method comprises: identifying the second locking means using second identification means.

Preferably, the method comprises: identifying the third locking means using third identification means.

Preferably, the method comprises: locating a vessel above the cover plate, the vessel configured to restrict unwanted matter from falling on the cover plate.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention and to show how the same may be carried into effect, there will now be described by way of example only, specific embodiments, methods and processes according to the present invention with reference to the accompanying drawings in which:

FIG. 1 illustrates schematically a typical prior art manhole shown in cross-section.

FIG. 2 illustrates schematically a cross-section view of a manhole and a temporary cover assembly for a manhole according to a first embodiment.

FIG. 3 illustrates schematically a bracket according to the first embodiment.

FIG. 4 illustrates schematically a bracket according to the first embodiment shown with a trench strut in place.

FIG. 5 illustrates schematically a procedure for fitting the temporary cover assembly for the manhole.

FIG. 6 illustrates schematically a plan view of the manhole showing the first embodiment after trench struts are put in place.

FIG. 7 illustrates schematically a plan view of a manhole after spacers are put in place.

FIG. 8 illustrates schematically a side cross-section view of the temporary cover assembly for a manhole comprising a cover plate.

FIG. 9 illustrates schematically a plan view of the cover plate for the temporary cover assembly for a manhole.

FIG. 10 illustrates schematically a cross-section side elevation view of a bracket according to a second specific embodiment.

FIG. 11 illustrates schematically a cross-section side elevation view of a collection vessel according to a third specific embodiment.

FIG. 12 illustrates schematically a plan view of a cover plate according to a fourth specific embodiment.

FIG. 13 illustrates schematically a side elevation view of a bracket and a trench strut according to a sixth specific embodiment.

DETAILED DESCRIPTION

There will now be described by way of example a specific mode contemplated by the inventors. In the following description numerous specific details are set forth in order to provide a thorough understanding. It will be apparent however, to one skilled in the art, that the present invention may be practiced without limitation to these specific details. In other instances, well known methods and structures have not been described in detail so as not to unnecessarily obscure the description.

The following description refers to cover assemblies used for covering manholes. However, it will be appreciated that the same apparatus and techniques can be used for covering other voids, such as gullies, trenches and the like.

Referring to FIG. 2 herein, there is illustrated schematically a cross-section view of a manhole and a temporary manhole cover assembly according to a first embodiment of the invention.

The temporary manhole cover assembly comprises a first bracket 201, and a second bracket 202. The first bracket 201 comprises a first bracket upper shelf 203 and a first bracket lower shelf 204. The second bracket 202 comprises a second bracket upper shelf 205 and a second bracket lower shelf 206. A trench strut 207 is disposed laterally between the first bracket 201 and the second bracket 202. The first bracket 201 and the second bracket 202 are located on the sides of an opening in the cover slab 105.

A trench strut 207 is an extendible prop that can be extended or retracted as required by a user. It can therefore be used to exert pressure on the sides of a trench or manhole to clamp things to the manhole. The trench strut 207 is positioned such that its first end lies between the first bracket upper shelf 203 and the first bracket lower shelf 204, and the second end of the trench strut 207 lies between the second bracket upper shelf 205 and the second bracket lower shelf 206.

The temporary manhole cover assembly further comprises a spacer 208, disposed between the first bracket 201 and the second bracket 202, and positioned on the first bracket upper shelf 203 and the second bracket upper shelf 205. A cover plate 209 is located above the spacer 208. The spacer 208 is configured to raise the cover plate 209 above the first bracket upper shelf 203 and the second bracket upper shelf 205.

Referring to FIG. 3 herein, there is illustrated schematically a first bracket 201 according to the first embodiment. The first bracket 201 comprises a first protrusion 301 located at its upper end, a lug 302 protruding above the first bracket upper shelf 203, a second protrusion 303 extending laterally from a lower surface of the first bracket upper shelf 203, and a third protrusion 304 extending laterally from an upper surface of the first bracket lower shelf 204. The second bracket has corresponding protrusions and lugs (not shown).

The first protrusion 301 is configured in use to sit on an upper surface of the cover slab 105. This provides a degree of mechanical stability when the temporary manhole cover assembly is being fitted. It also provides additional force to prevent the temporary manhole cover assembly from falling into the manhole. It is preferred, although not necessary, to form the first protrusion 301 out of a 16 mm steel bar. This can be welded to an upper surface of the first bracket 201. An advantage of using 16mm bar is that it provides sufficient mechanical rigidity to prevent the manhole cover from slipping into the manhole, but does not unduly restrict laying brickwork 104 on the cover slab 105.

The second protrusion 303 and the third protrusion 304 are configured to allow an end piece of the trench strut 207 to be located between a back wall 305 of the bracket, and the second and third protrusions 303, 304.

The lug 302 provides a point to which the cover plate 209 can be locked.

Referring to FIG. 4 herein, there is illustrated schematically a perspective view of a bracket 201 according to the first embodiment shown with a trench strut 207 in place.

An end piece 401 of the trench strut 207 is located between the second protrusion 303, the third protrusion 304 and the back wall 305 of the bracket 201. This prevents the trench strut 207 from moving in a perpendicular direction relative to the back wall 305 of the trench strut 201. To prevent the trench strut 207 from moving in a direction parallel to the plane of the back wall 305 of the bracket 201, four pins 402, 403, 404, 405 are provided. A first pair of pins 403, 404 are inserted through holes in the second protrusion 303 either side of the end piece 401 of the trench strut 207. A second set of pins 402, 405 are inserted through holes in the third protrusion 304 either side of the end piece 401 of the trench strut 207. In use, these pins prevent the trench strut from moving in a direction parallel to the plane of the back wall 305 of the brackets 201.

This is shown more clearly in FIG. 4b, which shows an end-on view of the trench strut 207 and the bracket 201.

Other means of preventing the trench strut 207 from moving in a direction parallel to the plane of the back wall 305 of the bracket 201 are possible. For example, a permanent lug (not shown) can be provided at one side of the trench strut end piece 401 to prevent the trench strut from moving past the permanent lug. A bolt or pin (not shown) can be located through an opening in the first bracket upper shelf 203 alongside the other side of the trench strut end piece 401 to prevent the trench strut 207 from moving past the bolt or pin. In this way, the trench strut is prevented from moving in a direction parallel to the plane of the back wall 305 of the brackets 201.

Referring to FIG. 5 herein, there is illustrated schematically a procedure for fitting the temporary manhole cover.

In typical use, the temporary manhole cover assembly is fitted once the manhole ring 102 and the cover slab 105 are already in place. One of the functions of the temporary manhole cover assembly is to reduce the risk of injury to personnel whilst the brickwork 104 is being laid. However, it is possible to retrofit the temporary manhole cover assembly to an existing manhole that already has brickwork laid if any repair work is required on the manhole.

At least one strut 207 is located 501 between a first bracket 201 and the second bracket 202 as shown in FIG. 4. For additional stability, strength and security it is preferred to use two trench struts, although only one trench strut is necessary. For larger manholes or trenches, more than two trench struts may be used. The following description assumes that two trench struts are used.

The length of each trench strut is adjustable. Before affixing the brackets and the trench struts to the manhole, it is desirable to adjust the strut strength to just below the dimensions of the gap in the cover slab 105. Adjusting the length of the struts 502 can be done either before step 501 or after step 501.

The brackets 201, 202 are placed 503 over the gap in the cover slab 105 such that the first protrusion 301 of the first bracket 201 and a corresponding first protrusion of the second bracket 202 are located on an upper surface of the cover slab 105.

The length of each trench strut 207 is extended 504, such that each trench strut 207 firmly affixes the first bracket 201 and the second bracket 202 to opposite sides of the gap in the cover slab 105. The combination of the protrusions located on the upper surface of the cover slab 105, and the pressure caused by the trench struts 201 affix the assembly firmly in place relative to the cover slab 105.

A spacer 208 is placed 505 on an upper surface of the first bracket upper shelf 203 and the second bracket upper shelf 205. The spacer 208 is provided for two main reasons. The first is that the trench strut 207 is extended by turning a handle (not shown). Before the assembly is fitted, it is not known whether the handle will protrude downwards into the manhole, or upwards above the upper shelves of the first and second bracket. If the handle is disposed upwards, then it may be located such that it would impinge on the cover plate 209. The spacer 208 provides some leeway if the handle of the trench strut 207 is disposed upwards. The other purpose of the spacer is to provide a reinforcing grid, such that the cover plate can be made of a less strong, and therefore less expensive or less dense material.

The cover plate 209 is placed 506 on top of the spacer 208.

The cover plate is locked to the lug 302 disposed on the first bracket upper shelf 203, and to a corresponding lug disposed on the upper shelf of the second bracket 205.

Typically, the cover plate comprises two cover plate sections. It is therefore also desirable to lock the two cover plate sections to each other 508.

The above order of assembly need not be followed strictly in order shown. It will be apparent that certain operations can be carried in different orders to that described above.

A further feature of the invention is that it can be used to provide a safe working environment both for manholes that are being constructed, and for existing manholes. If any work needs carrying out on an existing manhole, the assembly can be retrofitted to the existing manhole.

Referring to FIG. 6 herein, there is illustrated schematically a plan view of the manhole showing the first embodiment after trench struts are put in place.

A cover slab 105 typically comprises a substantially circular concrete biscuit with a substantially square hole 601 in its centre. When the brackets 201, 202 are placed 503 over the cover slab 105, the trench struts 207, 602 are extended 504 to tighten the fit of the assembly in the gap 601 of the cover slab 105.

Each trench strut 207, 602 is shown disposed between a first side 603 and a second side 604 of the gap 601 in the cover slab 105. The first protrusion 301 of the first bracket 201 is located on an upper surface of the cover slab 105 at the first end 603 of the gap 602. The first protrusion 605 of the second bracket 202 is shown disposed on an upper surface of the second end 604 of the cover slab 105.

Each trench strut 207, 602 is shown disposed between the first bracket upper shelf 203 and the first bracket lower shelf 204 at the first end 603 of the gap 601, and between the second bracket upper shelf 205 and the second bracket lower shelf 206 at the second end 604 of the gap 601 in the cover slab 105.

The portion of the assembly shown in FIG. 6 comprising the first bracket 201, the second bracket 202 and the trench struts 207, 602 provide a sufficiently firm fixing to the cover slab 105 on which the spacer 208 and the cover plate 209 can be laid.

Referring to FIG. 7 herein, there is illustrated schematically a plan view of a manhole after the spacer is put in place.

A spacer 208 is placed on the first bracket upper shelf 203 and the second bracket upper shelf 205. The spacer can be formed of any suitable shape and material. The spacer 208 is shown in FIG. 7 formed of two separate spacer sections formed from box-section steel. However, the spacer 208 may be formed of only one piece or more than 2 pieces as required by the dimension of the manhole. The first spacer section 701 is rectangular in shape and disposed between the first end 603 and the second end 604 of the gap 601 in the cover slab 105. The second spacer section 702 is similarly formed to the first section 701. There is a gap 703 between the first spacer section 701 and the second spacer section 702.

The gap 703 performs two functions: first, it allows the protrusion of locking lugs from the first bracket upper shelf 203 and the second bracket upper shelf 205. Secondly, the gap 703 enables the first spacer section 701 and the second spacer section 702 to be easily placed in position or removed as required, without the spacer sections 701, 702 becoming wedged in the gap 601 of the cover slab 105.

Referring to FIG. 8 herein, there is illustrated schematically a side cross-section view of the temporary manhole cover assembly comprising a cover plate.

The cover plate in this embodiment comprises a first cover plate section 801 and a second cover plate section 802. The first cover plate section 801 and the second cover plate section 802 are disposed on top of the first spacer section 701 and the second spacer section 702.

The first cover plate section 801 comprises an opening through which the lug 302 protruding above the first bracket upper shelf 203 can pass. The first cover plate section 801 further comprises a handle 803 to allow a user to easily lift the first cover plate section 801.

The second cover plate section 802 also comprises an opening through which a lug 804 protruding from an upper surface of the second bracket upper shelf 205 can pass. The second cover plate section 802 further comprises a handle 805 which allows a user to easily lift the second cover plate section 802.

The second cover plate section further comprises a central lug 806 extending laterally from an upper surface of the second cover plate section 802. The central lug 806 passes through an opening in the first cover plate section 801 at a region where the first cover plate section 801 and the second cover plate section 802 overlap 807.

There are therefore preferably three lugs protruding above the cover plate 209. Each lug is configured to be affixed to a lock. Any suitable lock may be used, for example a padlock operated by a key, a combination lock and so on. There are therefore preferably three points at which the cover plate 209 can be locked to the temporary manhole cover assembly. The first point is the lug 302. By attaching a lock to this lug when the first cover plate 801 is in place, the first cover plate section 801 is locked to the first bracket upper shelf 203 via the lug 302. By attaching a lock to the second lug 804, when the second cover plate section 802 is in place above the second spacer section 702, the second cover plate section 802 is locked to the second bracket upper shelf 205. By attaching a lock to the central lug 806, which extends from the second cover plate section 802 through an opening in the first cover plate section 801, the first cover plate section 801 and the second cover plate section 802 can be locked together.

Referring to FIG. 9 herein, there is illustrated schematically a plan view of the temporary manhole cover assembly comprising the cover plate 209. A first lock 901 is attached to the lug 302 that extends upwardly from the first bracket upper shelf 203 connecting the first cover plate section 801 to the first bracket upper shelf 203. A second lock 902 is affixed to the central lug 806, which extends upwardly from the second cover plate section 802 through an opening in the first cover plate section 801, thereby connecting the first cover plate 801 to the second cover plate 802. A third lock 903 is affixed to the lug 804 that extends upwardly from the second bracket upper shelf 205 through an opening in the second cover plate section 802, thereby locking the second cover plate section 802 to the second bracket upper shelf 205.

Each lock has its own key, combination number, or other means to open the lock. The means to open each lock 901, 902, 903 is different for each lock. Therefore, to restrict unauthorized access to the manhole, a user would need to obtain the means to open each lock 901, 902, 093 from a person who keeps the means to open these locks. On a building site this would usually be a site manager. These means could include keys or combination numbers.

The first cover plate section 801 comprises two identifiers 904, 905 which identify locks 901 and 902 respectively. The second cover plate section 802 also comprises an identifier 906 which identifies the third lock 903. If a person needs to access the manhole, they make a record of the identifiers 904, 905, 906 and approach the site manager who has the means to open the locks associated with each identifier 904, 905, 906. This will allow the site manager to identify the keys, combinations or other means to open the locks required and also allows the site manager to make a decision on whether to allow access to the manhole or to refuse access to the manhole.

According to a second specific embodiment, the brackets do not comprise a lower shelf. Referring to FIG. 10 herein, there is illustrated schematically a cross-section side elevation view of a bracket according to the second specific embodiment.

The bracket 1001 comprises a protrusion 301 at a first end configured to locate on a surface of the cover slab 103, a first bracket upper shelf 203, and trench strut end piece attachment means 1002.

The trench strut end piece attachment means 1002 comprises a projection disposed opposing the second protrusion 303. The second protrusion 303 and the trench strut end piece attachment means 1002 are configured to allow an end piece 401 of the trench strut 207 to be located between a back wall 305 of the bracket, and the second and third protrusions 303, 304.

An advantage of doing away with the lower shelf of each bracket and replacing it with a trench strut end piece attachment means 1002 is a saving in material costs. The second specific embodiment is in all other respects compatible with the first specific embodiment.

In a third specific embodiment, a collection vessel is provided that is located, in use, on the upper surface of the cover plate. Referring to FIG. 11 herein, there is illustrated schematically a cross-section side elevation view of a collection vessel 1100 according to the third specific embodiment.

The collection vessel 1100 has a base 1101, side walls 1102, 1103, and is open-topped. The bulk of any excess mortar dropped by a bricklayer, or any debris, dirt or silt from the building site that falls into the entrance of the manhole falls into the collection vessel 1100 and is substantially contained by the collection vessel 1100. When the brickwork 104 around the manhole is complete, and a permanent cover is ready to be put in place, the collection vessel 1100 is removed thereby removing most of the dirt, debris or silt that has entered the manhole. The vessel 1100 is equipped with handles to allow easy removal from the manhole.

As the collection vessel 1100 can be extremely heavy, for example if it has collected large amounts of building site debris such as concrete, it is provided with lifting means configured to be attached to a mechanical lifter. The lifting means comprises a ring 1104 disposed substantially at each corner of the collection vessel. When the vessel 1100 is to be lifted out of the manhole, hooks 1105 are attached to each ring 1104 and the collection vessel 1100 can be mechanically lifted.

There may also be provided a seal 1106 disposed around the outer side walls 1102, 1103 of the collection vessel 1100. The seal 1106 forms a seal between the brickwork 104 and the collection vessel 1100. This prevents mud, silt or other unwanted matter from falling down the outside walls 1102, 1103 of the collection vessel 1100. The seal comprises any suitable seal, such as an inflatable flexible tube or a compressible material.

The collection vessel 1100 can also be used where the temporary manhole cover assembly is retrofitted to an existing manhole.

The third specific embodiment is otherwise compatible with the first and second specific embodiments.

In a fourth specific embodiment, the cover plate comprises a first cover plate section and a second cover plate section, which do not overlap. Referring to FIG. 12 herein, there is illustrated schematically a plan view of a cover plate according to the fourth specific embodiment.

The cover plate 209 comprises a first cover plate section 1201 and a second cover plate section 1202. The first cover plate section 1201 has a handle 1203, and the second cover plate section has a handle 1204. The handles are provided to allow a user to easily remove the cover plate sections 1201, 1202 when required. The first cover plate section 1201 comprises an opening through which a lug 302 extending from the first bracket upper shelf 203 may pass. The second cover plate section 1202 comprises an opening through which a lug 804 extending from the second bracket upper shelf 205 may pass.

In use, the cover plates 1201, 1202 are placed over the space 208 such that the lug 302 extending from the first bracket upper shelf 203 passes through the opening in the first cover plate 1201 and the lug 804 extending from the second bracket upper shelf 205 passes through the opening in the second cover plate 1202. A first lock 901 is then attached to the first lug 301 and a third lock 902 is attached to the lug 804 extending through opening in the second cover plate 1202.

There is no need for a second lock to lock the first cover plate section 1201 to the second cover plate section 1202, although this may be provided if additional security is required.

The fourth specific embodiment is otherwise compatible with any of the aforementioned specific embodiments.

In a fifth specific embodiment, a protecting liner is provided to surround the cover plate 209. The cover plate is not a snug fit over the gap 601 in the cover slab 103. This is to accommodate different tolerances of size and to prevent the cover plate 209 from becoming wedged in the gap 601. However, some debris from the building site may pass through the space between the outside of the cover plate 209 and the gap 601 in the cover slab 203. In particular, wet matter such as silt may pass through this gap. There is therefore provided a protecting liner (not shown) that is configured to be placed around the outside edge of the cover plate 209 to close the space between between the outside of the cover plate 209 and the gap 601 in the cover slab 203.

The protecting liner may be formed of any suitable material, although it is preferred to use a flexible material such as polyethylene or polyethylene terephthalate (PTFE). However it is envisaged that compressible materials may also be used to substantially seal the space between the outside of the cover plate 209 and the gap 601 in the cover slab 203.

In a sixth specific embodiment, a substantially u-shaped locking pin is provided that acts as both a locking point, and means to prevent the trench strut from moving relative to the brackets.

Referring to FIG. 13 herein, there is illustrated schematically a side elevation view of a bracket and a trench strut according to the sixth specific embodiment.

The bracket 201 comprises a first bracket upper shelf 203 and a first bracket lower shelf 204. A trench strut 207 is disposed between the first bracket upper shelf 203 and the first bracket lower shelf 204. The end piece 401 of the trench strut 207 is disposed between the first bracket upper shelf 203 and the first bracket lower shelf 204. A substantially u-shaped locking pin 1301 is provided that performs three functions. The locking pin performs the same function as the lug 302 described in the previous embodiments, in that it allows locking means to be attached to the locking pin 1301. The locking pin 1301 also prevents the trench strut 207 from moving in the same plane as the back wall 305 of the bracket 201. The locking pin 1301 also prevents the trench strut 207 from moving in a substantially perpendicular direction relative to the back wall 305 of the bracket 201.

The locking pin 1301 comprises a substantially unshaped section of steel. The locking pin 1301 comprises a first leg section 1306, a second leg section 1307, and a locking section 1308 disposed between the first leg section 1306 and the second leg section 1307. The first bracket upper shelf 203 comprises two holes. The first hole is configured to allow the first leg section 1306 to pass through the first hole, and the second hole is configured to allow the second leg section 1307 to pass through the second hole. When the trench strut 207 is put in place with its end piece 401 against the back wall 305 of the bracket 201, the first leg section 1306 of the locking pin 1301 is passed through the first hole, and the second leg section of the locking pin 1301 is passed through the second hole of the first bracket upper shelf 203. The locking pin 1301 is fixed in place relative to the first bracket upper shelf 203 by a first nut 1303 and a first washer 1305 disposed either side of the first bracket upper shelf 203 on the locking pin 1301 first leg section 1306, and a second nut 1302 and second washer 1304 disposed either side of the first bracket upper shelf 203 on the locking pin 1301 second leg section 1307. In this way, the locking pin 1301 is releasably fixed relative to the first bracket upper shelf 203 and hence to the bracket 201.

Once the locking pin 1301 is fixed in place relative to the bracket 201, the trench strut 207 is also fixed in place relative to the first bracket 201. This is because the locking pin 1301 first leg section 1306 and the locking pin 1301 second leg section 1307 are disposed either side of the trench strut 201, which prevents the trench strut 201 from moving in the same plane as the back wall 305 of the bracket 201. The first leg section 1306 and the second leg section 1307 are also disposed in front of the end piece 401 of the trench strut 207, and so the trench strut 207 cannot move in a perpendicular direction relative to the back wall 305 of the bracket 201. The end piece 401 is sandwiched between the back wall 305 on one side, and the first leg section 1306 and the second leg section 1307 on the opposite side.

The locking section 1308 is configured to pass through a hole in the cover plate 209 once the cover plate 209 is in position. Locking means can then be attached to the locking section 1308, to lock the cover plate 209 in place relative to the bracket 201.

The sixth specific embodiment is otherwise compatible with any of the first to fifth specific embodiments.