GB2405895A

GB2405895A - Trench cover

Info

Publication number: GB2405895A
Application number: GB0321047A
Authority: GB
Inventors: John Prigmore
Original assignee: BUZZ Inc Ltd
Current assignee: BUZZ Inc Ltd
Priority date: 2003-09-09
Filing date: 2003-09-09
Publication date: 2005-03-16
Anticipated expiration: 2023-09-09
Also published as: GB0321047D0; GB0416897D0; GB2405895B

Abstract

A cover 100 for temporarily covering a trench 401 by extending over and resting on the ground on opposite sides respectfully of the trench. The cover is manufactured from polyethylene and is designed for use mainly in pedestrian areas. A plurality of polyethylene rib members may be permanently fixed to the cover. A plurality of steel ribs may be detachably attached to the underside of the cover.

Description

Trench Cover

Field of the Invention

This invention relates to a cover suitable for temporarily covering a trench in a public thoroughfare such as a road or footpath, for example overnight until work starts again.

Backaround to the Invention

The disruption caused to public highways by the creation of trenches is all To the more acute if such work completely impedes access through the region of work. In addition to this the presence of open trenches is a hazard to health due to the likelihood of members of the public falling into the trench and causing themselves serious injury. Hence, normally when work involves the creation of trenches to access buried structures such as gas, electricity or water pipelines, the resulting trenches are normally either sealed off by way of highly visible barriers or protected with covers.

Many types of trench covers are already in use, the most common types consist of elongate plates usually made of steel or other metals which are laid 2 o over the trench with the covers being supported by the ground on opposite sides of the trench or trench covers consisting of some form of timber or metal laminated with a plastic.

Normally a number of such plate covers are used with their edges touching.

: The major problems with such plate covers are: (1) The weight of these plates makes them cumbersome to move to and from a work site and also difficult to position with any finesse; (2) Even though they are relatively heavy they can be moved length wise and transversely off of the trench by vibrations imparted by the movement of traffic such as vehicles or people over the plate. Such movement can result in dangerous gaps occurring between the plates and the consequent possibility of accidents. If transverse movements are too great there is the risk that one or more plate cover will be tipped into the trench. In order to minimise these movements, the cover can either be inset into the road or path surface or use rubble, asphalt or other suitable materials to provide stops. Even when such precautions are taken these plate covers can still work loose e.g. by heavy vehicular or foot traffic.

To overcome these problems trench covers have been designed which are interlockable with other identical trench covers so as to form a large assembly of covers linked together. Such an assembly of trench covers minimizes longitudinal and lateral movement. Reducing the problems of gapping between o the ends of adjacent covers.

It is important that such temporary trench covers can be laid accurately and removed quickly and easily for re-use. A large assembly of trench covers as described above is not easily maneuvered and so a significant amount of work is needed to reposition the covers should the work site move on even small distances The use of recycled materials is becoming more and more important as benefits of ecologically sound business practices are acknowledged by all sectors do of industry. The prior art trench covers described above are not designed to be recycled and in particular covers which comprise more that one material i.e. laminated steel are almost impossible to recycle and so once damaged or worn so as to become unusable are simply discarded.

as The vast majority of trenches are dug to repair, replace or maintain utility pipeline networks such as gas, water and electricity. Polyethylene tubes being used to replace aging pipelines, and damaged modern pipe work being similarly replaced with new polyethylene pipe work. Each year therefore utility companies improvement works involved with replacement of existing pipe work dispose of so over 1 million tons of waste polyethylene. Some of this waste material goes to plastic reclamation companies where it is granulated and mixed with other plastics to be sold on as a low-grade plastic. Such low-grade plastics being used predominantly as packing material. The remainder is discarded into landfill or other refuse centers.

The properties and benefits of polyethylene are well known, and are the strength and durability of this material. These mechanical features make it a valuable product in both the utility industries for the replacement of degraded pipe work infrastructures. The inventors believe these properties also make it a valuable material for the manufacture of trench covers.

To There therefore exists a large amount of scrap polyethylene from damaged or the off-cuts of pipeline used in the upgrading and maintenance of the utility networks and it is an object of the present invention to provide a product recycled from this material.

Therefore the object of the present invention is to provide a cover for temporarily covering a trench and in which the aforesaid disadvantages of prior art trench covers are minimised or avoided entirely and to provide a trench cover which utilizes recycled materials and is itself recyclable, such as a trench cover made from polyethylene.

Summarv of the Invention According to a first aspect there is provided a cover for temporarily covering a trench by extending over and resting on the ground on opposite sides respectfully of the trench, wherein said cover comprises polyethylene.

Preferably wherein the cover comprises a plurality of rib members Preferably wherein said cover comprises recycled polyethylene.

o Preferably wherein said plurality of rib members is permanently fixed to said cover.

Preferably wherein said plurality of rib members comprise polyethylene.

Preferably wherein at least one of said plurality of rib members is configurable to detach from said cover.

Preferably wherein said at least one rib member comprise metal.

2 o Preferably wherein said at least one rib member comprise steel.

Preferably wherein said at least one rib member is configured so as to be substantially inserted into said cover.

Preferably wherein said cover comprises four rib members.

Preferably wherein said cover comprises attachment means configurable to detachably secure said cover to a surface.

o Preferably wherein said attachment means comprise at least one hole formed at a substantially vertical angle relative to said surface; Wherein said hole is configurable to accept a bolt that is driven into said surface to secure said cover.

Preferably wherein the cover comprises four holes.

Preferably wherein said cover is configured for use exclusively in pedestrianised areas.

Preferably wherein said cover is between 60 cm and 150 cm long.

Preferably wherein said cover is 100 cm long.

Preferably wherein said cover is between 60 cm and 150 cm wide.

Preferably wherein said cover is 100 cm wide.

Preferably wherein the edges of said cover are configured such that they slope from the surface in contact with the floor up to a raised central portion of the cover.

According to a first aspect there is provided a method of manufacturing a cover for a trench, comprising the following steps: Introduction, heating and liquidisation of polyethylene in heated cylinder; Bring front and back moulds together, forming the injection chamber between said front and back moulds; Inject molten polyethylene into chamber; Leave to said molten polyethylene to set; Withdraw moulds; Remove cover.

Preferably wherein said front and back moulds are cooled.

Preferably wherein said front and back moulds are cooled with a circulating water system.

Brief Descrintion of the Drawinas 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: Figure 1 shows a top down view of a trench cover according to a first specific embodiment of the present invention.

Figure 2 shows a down top view of a trench cover according to a first specific embodiment of the present invention.

Figure 3a shows a top down view of one corner of a trench cover according to a first specific embodiment of the present invention.

Figure 3b shows a down top view of one corner of a trench cover according to a first specific embodiment of the present invention Figure 4 shows a perspective view of a trench cover according to a first o specific embodiment of the present invention in use Figure 5 shows a top down view of a trench cover according to a second specific embodiment of the present invention. Feature of the trench cover being cutaway to display the metal support members running across the cover.

Detailed Descrintion 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.

According to a first specific embodiment of the present invention and with reference to Fig. 1 herein there is provided a trench cover 100. Figure 1 shows the upper surface of the trench cover 101. The trench cover 100 is 100 cm long and 100 cm wide. According to alternate embodiments of the present invention the size of the trench cover may be altered to any size although the inventors s consider trench covers in the range 60 cm up to 150 cm to be the most useful.

According to this first specific embodiment of the present invention when the trench cover is placed upon the ground such that the upper surface of the cover 101 is not in contact with the ground and is exposed to the environment. The So lower surface 201 as shown herein figure 2, of the trench cover is in contact with the ground.

The edges of the trench cover 102 are angled such that a central portion 103 of the trench cover is raised off of the ground relative to the edges 102 of the trench cover 100. The edges are angled such that the edges of the trench cover are angled so as to facilitate the easy movement of pedestrian traffic such as foot or wheeled traffic up to the raised area in the center of the trench cover. Lowering the risk of pedestrians tripping or stumbling or otherwise injuring themselves as may occur if the transition from ground level to the raised cover was more abrupt.

So These edges are smoothed so as to decrease the chances of pedestrian traffic becoming caught on the cover, again reducing the chances of injury or incident.

According to this first specific embodiment, in order to impart greater structural strength and rigidity to the trench cover the lower side of the cover 201 consists of a regular pattern of supporting straight ribs projecting from opposite sides of the trench cover. In addition to this there are also 2 diagonal ribs 203 positioned between diagonally opposed corners of the trench cover, again, to impart greater structural strength and rigidity to the trench cover. This honeycomb arrangement of supporting rib members increases the structural rigidity and strength of the trench cover whilst reducing the weight of the cover due to the spaces between the ribs. According to this first specific embodiment of the JO present invention there are 19 longitudinal and 19 lateral supporting rib members and 2 diagonal rib members. These are all formed from the same polyethylene plastic of which the rest of the article is comprised. The inventors consider this honeycomb pattern of support members to be an improvement over solid prior art covers because of the reduced amount of material involved in the manufacture of such covers and there lighter weight in comparison to sold boards.

The corners of the trench cover 103 are rounded as well as being angled so as to present no sharp edges to pedestrian traffic walking across the trench cover. This configuration is intended to reduce the likelihood of pedestrian traffic o tripping or striking the cover causing injury to themselves and/or movement of the cover.

The upper surface 101 of the trench cover comprises a pattern of raised elements 104. The purpose of this pattern is to prevent slippage on the trench cover in adverse weather conditions for example rain or snow.

The trench cover is manufactured from polyethylene. Any source of polyethylene is suitable for the manufacture of the trench covers but the inventors consider waste polyethylene produced by the replacement of existing utility pipe o work to be particularly appropriate for the manufacture of trench covers according to the various embodiments of this invention.

The inventors consider the trench covers of this invention to be particularly useful in pedestrian areas.

One of the main benefits of the new invention is to reduce the impact of the large volumes of plastic and general waste material going to Landfill each year from the utility industries. When trench covers produced from metal, timber or fiberglass are damaged or become distorted they are designated as not fit for purpose and sent to landfill. This is because such prior art covers are prohibitively expensive to recycle and/or in many cases recycling is not possible To at all. This inability to recycle has implications in terms of the costs associated with skip hire, waste transport and landfill fees as well as the more general environmental impact issues.

Current environmental standards focus on continual improvement for companies generating waste products. Actively reducing waste materials is a priority in all industries, however, once achieved there will always be a percentage that will not fall into any re-useable category. This is then when recycling becomes the only viable and cost effective alternative.

Most other waste streams have been targeted by Government agencies looking to minimise landfill. It is the accepted that emphasis will be placed in the coming years on recycling plastic products. This will apply to the domestic user but will specifically focus on larger producers of plastic waste material. The recycled trench cover of the present invention therefore is one step ahead of forthcoming legislation regarding disposal and duty of care relating to plastics.

The trench cover further comprises means to secure the cover to the ground upon which it rests. The unwanted movement of trench covers is a serious problem, the dangers of gaps appearing between adjacent covers or even more dangerous covers moving so as to fall into the trench, pose serious problems to the organizations responsible for ensuring the safety of such sites.

According to this first specific embodiment of the present invention the securing means consist of 4 holes 105, 106, 107, 108 positioned in the 4 corners of the trench cover at the boundary between the edges of the cover and the central portion. These holes are made at a 90 angle relative to the longitudinal axis of the cover. According to alternate embodiments of the present invention the hole maybe made at a wide range of angles relative to the longitudinal axis.

The holes 105, 106, 107, 108 are configured to allow the entry of the securing bolts which are used to secure the trench cover to the ground. These JO holes are positioned at the confluence of the diagonal reinforcing ribs and two of the straight strengthening ribs so as to increase the strength and security of the cover when the bolt is in place shown in figure 3b herein. In use bolts may be driven into the supporting surface using a wide range of means for example a pneumatic gun, screw or drilling action or simple hammering. A corner of a cover 100 viewed from above and below the cover, with a securing bolt is shown in figures 3a and 3b herein respectively.

The cover according to this first specific embodiment is much lighter than alternative products available at the moment weighing only 10/ kilos as opposed to 16.3 kilos for a prior art wooden trench cover. The lightweight construction of the new cover facilitates easy lifting and handling reducing the chances of stress related injuries to the cover. The board has a honeycomb design, this combined with the lighter weight of polyethylene in comparison to more traditional materials especially metals, means that the board can be easily maneuvered into position.

By reducing weight it is also possible to actively increase the loading capacity on vehicles carrying the covers. Meaning that either a vehicle would be able to carry more products in one trip or alternatively vehicles could carry less weight but an equivalent number of covers. In either case it would require less so fuel to deliver a given cover resulting in reduced emissions and a decline in the environmental impact.

As previously stated this new invention is 100% recycled. It is envisaged that much of the waste the plastics produced by the utility companies in a given year could be reused in the creation of these trench covers which would significantly reduce the volumes of waste plastic reduced in a year.

Another benefit of the present invention is that when working on improving the pipeline infrastructure it is important sometimes to work around street furniture without jeopardizing pedestrian safety. With the new cover being constructed from plastic, employers can easily cut sections of the board to To facilitate fitting to street furniture or household pipe work e.g. lamp posts, drain pipes or rain water pipes. Neither board or the section removed would be considered waste, as they can be both returned to the depot and placed in the designated plastic skip to await recycling into more boards.

For natural gas contractors such as Transco the board has been further modified to allow the ventilation of gas from sites. Ventilation points can be made into the invention to allow gas to escape in a controlled manner whilst emergency work is undertaken. Once again, any section of the board removed for this activity can be easily recycled. Or alternatively small holes maybe made in the 2 o cover at the time of manufacture.

With reference to figure 4 herein, there is shown a trench 401, positioned over this trench is a cover 100 according to this first specific embodiment of the present invention. The cover extends over the trench and rests on the ground on opposite sides of the trench. The cover has been securely fastened to the ground via four bolts. Each bolt is positioned through the four holes made in the cover, which are positioned in each corner of the cover.

According to a second specific embodiment of the present invention there is so provided a cover much as previously described, which further comprises metal support members to increase the structural strength of the cover.

With reference to figure 5 herein, there is shown a cover 501 much as previously described in a cutaway view showing the metal support members 502, 503, 504, 505 running through the cover. According to this second specific embodiment of the present invention these metal support members are made from steel.

In this second specific embodiment there are four metal support members, trench covers with different numbers of support members are possible according to the specific requirements of the work site in which the cover will be used.

The metal support members are removable from the cover, so as to increase the range of configurations available with the trench cover.

There will now be described by way of example a specific method 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

2 0 unnecessarily obscure the description.

The manufacture of the covers that are the subject of this invention is by plastic injection molding. Standard injection molding apparatus and methodologies are used in the manufacture of these articles.

Firstly, refined polyethylene is introduced into the injection chamber. This chamber is in the form of a heated cylinder. The polyethylene is heated and enters a semi-liquid state.

3 o In an adjoining chamber a front and back mould corresponding to the upper and lower surfaces of the cover are brought together and pressure is exerted onto these moulds so as to form a sealed chamber.

The pressure in the heated cylinder is increased so as to force molten polyethylene into the sealed chamber, filing the space between the moulds with polyethylene.

As the moulds are not heated the polyethylene cools and solidifies forming a solid structure as defined by the front and back moulds.

Once the polyethylene has sufficiently solidified the moulds are separated To and the newly formed cover is removed.

In a further aspect of the present invention the front and back moulds maybe cooled, so as to decrease the cooling period required for the molten polyethylene to solidify and leading to an increase in production rates of the cover. This cooling maybe mediated via a circulating water system or any other

suitable means.

Claims

Claims: 1. A cover for temporarily covering a trench by extending over and

resting on the ground on opposite sides respectfully of the trench, wherein said cover comprises polyethylene.
2. A cover as claimed in claim 1, wherein the cover comprises a plurality of rib members 3. A cover as claimed in claimed in claim 1 or 2, wherein said cover o comprises recycled polyethylene.
3. A cover as claimed in any preceding claim, wherein said plurality of rib members is permanently fixed to said cover.
4. A cover as claimed in claim 4, wherein said plurality of rib members comprise polyethylene.
5. A cover as claimed in anyone of claims 1, 2 or 3, wherein at least one of said plurality of rib members is configurable to detach from said cover.
6. A cover as claimed in claim 5, wherein said at least one rib member comprise metal.
7. A cover as claimed in claim 6, wherein said at least one rib member comprise steel.
8. A cover as claimed in claim 6, 7 or 8, wherein said at least one rib member is configured so as to be substantially inserted into said cover.

o
9. A cover as claimed in anyone of claims 6, 7, 8 or 9, wherein said cover comprises four rib members.
10. A cover as claimed in any preceding claim, wherein said cover comprises attachment means configurable to detachably secure said cover to a surface.
11. A cover as claimed in claim 10, wherein said attachment means comprise at least one hole formed at a substantially vertical angle relative to said surface; Wherein said hole is configurable to accept a bolt that is driven into said To surface to secure said cover.
12. A cover as claimed in claim 11, wherein the cover comprises four holes.
13. A cover as claimed in any preceding claim, wherein said cover is configured for use exclusively in pedestrianised areas.
14. A cover as claimed in any preceding claim, wherein said cover is between 60 cm and 150 cm long.
15. A cover as claimed in any preceding claim wherein said cover is cm long.
16. A cover as claimed in any preceding claim wherein said cover is 2 5 between 60 cm and 150 cm wide.
17. A cover as claimed in any preceding claim wherein said cover is cm wide.

o
18. A cover as claimed in any preceding claim wherein the edges of said cover are configured such that they slope from the surface in contact with the floor up to a raised central portion of the cover.
19. A method of manufacturing a cover for a trench, comprising the following steps: Introduction, heating and liquidisation of polyethylene in heated cylinder; Bring front and back moulds together, forming the injection chamber between said front and back moulds; o Inject molten polyethylene into chamber; Leave to said molten polyethylene to set; Withdraw moulds; Remove cover.
20. A method as claimed in claim 19, wherein said front and back moulds are cooled.
21. A method as claimed in claim 20, wherein said front and back moulds are cooled with a circulating water system.