WO2022195294A1

WO2022195294A1 - Temporary cover

Info

Publication number: WO2022195294A1
Application number: PCT/GB2022/050693
Authority: WO
Inventors: Christopher Whiteley
Original assignee: Oxford Plastic Systems Limited
Priority date: 2021-03-19
Filing date: 2022-03-18
Publication date: 2022-09-22
Also published as: GB2604929A; GB202103892D0

Abstract

A narrow-trench cover plate (10) for temporarily covering a length of a micro-trench or narrow trench comprises a moulded plastics body (12) providing an elongate floor plate having a top face (14) and an underside face, the underside face comprising one or more fixed retainer structures (18; Fig. 2) protruding from the underside face so as to extend into a trench over which the cover plate (10) is to be placed, wherein the cover plate further comprises one or more high-visibility elements (50a, 50b, 50c) on the top face (14), the high-visibility elements being of contrasting colour to the top face.

Description

Temporary Cover

Field of the Invention

The present invention relates to temporary narrow-trench covers, particularly to plastics material narrow-trench cover plates or micro-trench cover plates to be installed in a series of such plates that are of a size and weight suitable for a one-person lift, typically fewer than 10 kilograms and likely to have fewer than 5 kilograms.

Background

Temporary trench covers are used to reduce the hazard posed by an open trench excavated for construction or installation works. Generally, such trenches are excavated by machinery such as bucket excavators to provide a trench having a width and depth in the region of half a metre or more. In recent years, so-called micro trenching, or narrow-trenching, has been established as an alternative to trench excavation. Micro-trenching involves cutting a comparably small, shallow trench, or “micro trench”, of about 2-5 centimetres width, into a pavement. Similarly, “narrow trenching” involves similarly small trenches of 7 to 10 centimetres, sometimes 15 centimetres width and about 7 to 15 centimetres depth, into a pavement, typically using a rotary cutter. Micro-trenching and narrow-trenching are used particularly for the installation of fibre-optics infrastructure. Compared to conventional trench excavation, micro-trenching and narrow-trenching allow a several hundred metres long trench to be formed in a day, which poses a difficulty of on-site supervision of trip hazards until a micro-trench is back filled.

As a temporary cover for such micro-trenches, attempts of recent years include the use of expansion joint-type covers (see, e.g., Duratex Rubber and Plastics Ltd., Case Study: Microtrench cover for FTTH network installation in York, available at duratex.co.uk, “https://www.duratex.co.uk/company-blog/case-studies/case-study- microtrench-cover-for-ftth-network-installation-in-york”), in the form of an extrusion of several metres length comprising a generally trapezoid body with lateral wings, the body to be located in a micro-trench to be supported by the wings on either side of the micro-trench. In Great British Patent Publication GB2553006A it is suggested to incorporate anti-slip features, such as ridges, on the surface of such a temporary cover. The present invention seeks to provide an alternative to known narrow trench covers.

Summary of the Invention

In accordance with a first aspect of the invention, there is disclosed a narrow-trench cover plate as defined in claim 1. The narrow-trench cover plate is a cover plate for temporarily covering a length of a micro-trench or of a narrow trench. The cover plate comprises a moulded plastics body providing an elongate floor plate comprising a top face and an underside face. The underside face comprises one or more fixed retainer structures protruding from the underside face so as to extend into a trench over which the cover plate is to be placed. The cover plate further comprises one or more high- visibility elements on the top face, the high-visibility elements being of contrasting colour to the top face.

The plate is suitable for handling by a single person, and in particular suitable for installing cover plates over several tens if not hundreds of metres of trench in a day. The cover plate has a weight of no more than 15kg, and depending on the type of application, embodiments may have a weight not exceeding 10kg, 7kg, 5kg, or 3kg. While weight limits are subject to ongoing regulatory review, to provide an illustration of typical health and safety regulations, a product weighing no more than 3 kg may be allowed to be lifted above shoulder height by a single person, and may be lifted at lower leg height with stretched arms by a single person.

Herein, the expression “longitudinal” will be understood as the general extension of a narrow-trench or micro-trench, generally aligned with the elongate extension of the narrow-trench cover placed over it, including an end-to-end series of narrow-trench cover plates. The expression “lateral” denotes the direction perpendicular to the general narrow-trench extension.

The floor plate is sufficiently sturdy (exemplary dimensions provided below) to support the weight of a passenger when placed on a relatively even ground such as a pavement surface with a micro-trench gap or narrow trench gap in the region of a few centimetres underneath. The retainer structures provide a locator function, by hindering lateral displacement of a narrow-trench cover plate when hanging into a narrow-trench. The face of the cover plate comprising the retainer structures is understood to constitute the in use ground facing side, or underside, whereas the top side is generally flat to reduce trip hazards. It will be understood that the retainer structures are positioned on the underside to allow the elongate extension of the floor plate to follow the longitudinal extension of the trench. The top side may comprise anti-slip features such as protrusions.

The high-visibility elements are understood to be of a brighter colour than the moulded plastics body, e.g. yellow, white or orange, contrasting with the moulded plastics body and thereby of high visibility.

In some embodiments, the high-visibility elements are made from a plastics material.

The plastics material may be virgin plastics material such as HDPE plastic of a bright colour.

In some embodiments, the moulded body is made from recycled plastics material.

Recycled plastics material, such as recycled PVC, can be made of relatively high density and rigidity suitable as a floor cover plate.

In some embodiments, the high-visibility elements are retained in the floor plate by being partially overmoulded.

In some embodiments, the moulded body comprises one or more seating locations in the top face. In some embodiments, each seating location comprises a surface profile corresponding to a seating surface of a high-visibility element. Alternatively, the surface profiled of one or more seating locations corresponds to that of a seating surface to an extent sufficient to support the high-visibility element.

A plurality of seating locations may be spaced apart on the top face. The floor plate may comprise one or more sockets constituting seating locations for a high-visibility element. It will be understood that the “seating location” is a surface of the floor plate. The seating surface of the high-visibility element is the underside face to lie on the seating location.

In some embodiments, the one or more seating locations are flat, corresponding to a flat seating surface of the high-visibility elements.

In some embodiments, the one or more seating locations may comprise a recess, for instance at a location of a sprue. In that manner, portions of a sprue may protrude somewhat from the body of the floor plate, within the recess, and the high-visibility element may be used to conceal the sprue by bridging the recess. The high-visibility elements may comprise a recess in their seating surface, the recess providing clearance for a sprue structure or surface unevenness such as may be expected to remain after injection moulding. It will be appreciated that embodiments with recess may also comprise a generally flat seating location for support of a correspondingly shaped seating surface of the high-visibility element, for instance in the form of a flat seating location surrounding the recess at least in part, or surrounding the recess.

In some embodiments, an anchoring portion of a high-visibility element protrudes through the floor plate and extends beyond the underside face.

The high-visibility element may comprise one or more anchoring portions, such as a clip arrangement to snap into a corresponding aperture or socket within the floor plate.

In some embodiments, one or more anchoring portions of the high-visibility elements are within a footprint of the one or more retainer structures.

The retainer structure may be a unitary body, such as a solid body or a network of interconnected ribs. Alternatively, the retainer structure may be provided by an arrangement of structures such as ribs. In that manner, a free space may be provided between retainer structures. The retainer structure has typically a width of a few centimetres, e.g. 7 centimetres, corresponding to the narrow-trench or micro-trench into which it is to be inserted, to be able to abut laterally against a trench wall and resist lateral displacement, whereby a certain amount of leeway may be tolerable in practice. E.g., a retainer having a width of 5 centimetres may be used for a trench of 10 centimetre width. By positioning the high-visibility elements within the footprint of the retainer structure, they are better protected against impact.

In some embodiments, at least a portion of a high-visibility element forms part of the retainer structure.

For instance, one or more anchoring portions of the high-visibility element may be outside the footprint of a retainer structure. In embodiments, the anchoring portions of the high-visibility elements form the retainer structure.

In some embodiments, one or more high-visibility elements comprise anti-slip features, such as a surface profile comprising anti-slip protrusions.

It will be understood that the anti-slip features are provided on the top surface, or upward-facing surface, of a high-visibility element.

In some embodiments, the cover plate further comprises an end-to-end connector arrangement, the connector arrangement comprising at one plate end a connector pin structure and at the opposite plate end a connector ring structure.

In accordance with a second aspect of the invention, there is disclosed a narrow-trench cover plate as defined in claim 12. The cover plate is a narrow-trench cover plate for temporarily covering a length of a narrow-trench or of a micro-trench. The cover plate comprises a moulded plastics body providing an elongate floor plate having a top face and an underside face, the underside face comprising one or more fixed retainer structures protruding from the underside face so as to extend into a narrow-trench over which the cover plate is to be placed, wherein the cover plate further comprises an end-to-end connector arrangement, the connector arrangement comprising a connector pin structure protruding beyond the floor plate and a connector ring structure extending underneath and protruding beyond the floor plate.

The connector ring structure provides a recess that extends beyond the floor plate, such that a connector pin of an adjacent cover plate can be introduced from above. In some embodiments, the connector ring structure is as wide as the one or more retainer structures.

In some embodiments, the connector ring structure comprises a generally quadrilateral circumference.

In some embodiments, the connector ring structure is open so as to avoid the collection of fluid.

By providing a ring structure without floor plate, the collection of surface water or rain water can be avoided. The ring structure may also be used to hang up the cover plate on racking.

In some embodiments, the connector pin structure comprises a flat top surface extending in the plane of the underside face, to abut the underside of an adjacent cover plate.

In some embodiments, the connector pin comprises a hole.

The hole may have a diameter suitable to receive a bolt or screw to allow two adjacent cover plates to be bolted together when the hole of the connector pin structure is located underneath an adjacent cover plate.

In some embodiments, the connector pin structure comprises a wall structure extending perpendicularly downward from the underside face, a lower end of the wall structure comprising a rounded insertion heel.

In some embodiments, the connector pin structure tapers laterally with increasing distance from the floor plate.

In some embodiments, an end of the floor plate is concavely curved and the other end of the floor plate is correspondingly convexly curved so as to allow a scalloped end-to- end abutment. In some embodiments, the narrow-trench cover plate has a width at least three times the width of the retainer structure.

In accordance with a third aspect of the invention, there is disclosed a mould as defined in claim 22. The mould is for a narrow-trench cover plate according to embodiments of the first or second aspect. The mould comprises one or more mould portions that provide a cavity corresponding to a generally flat cover plate with one or more fixed retainer structures and one or more seating locations for receiving a high- visibility element to be provided.

Any features and feature combinations described herein in relation to embodiments the first, second or third aspect may be used with embodiments of the other aspects. The mould in accordance with the third aspect may comprise mould portions complementary to, and suitable for forming, features described in relation to one or more embodiments of the other aspects.

Description of the Figures

Exemplary embodiments of the invention will now be described with reference to the Figures, in which:

Figure 1 shows a perspective top view of a narrow-trench cover plate;

Figure 2 shows a perspective underneath view of the Figure 1 plate;

Figure 3 shows a top plan view of the Figure 1 plate;

Figure 4 shows a side elevation of the Figure 1 plate;

Figure 5 shows an underside view of the Figure 1 plate;

Figure 6 shows an end view of the Figure 1 plate,

Figure 7 shows a section detail of Figure 4,

Figure 8 shows an underside view of portions of two connected narrow-trench cover plates;

Figure 9 shows an underside view of a variation of the Figure 8 arrangement;

Figures 10A and 10B each show a step of a connection sequence, showing schematic portions of two narrow-trench cover plates in profile view;

Figures 11 A and 11 B each show another step of a connection sequence; and Figure 12 shows another step in a connection sequence. Description

Referring to Figures 1-6, disclosed herein is a narrow-trench cover plate 10 comprising a plate body 12 with a first side 14 and a second side 16. In use, the first side 14 constitutes a top (upward-facing) face of the plate body 12 and the second side 16 constitutes an underside face, to be placed on ground underneath. A rib arrangement 18, constituting a retainer structure, extends from the second side 16. The rib arrangement is provided in the form of a single continuous body. In embodiments, separate retainer structures may be provided along the second side.

In plan view (cf. Figures 3 and 5), the plate body 12 is elongate with a generally rectangular outline, and comprises a first end 20, oppositely a second end 22, and laterally two elongate ends 24a, 24b, with a body length defined by the distance between the first end 20 and the second end 22, and a body width defined by the distance between the two elongate ends 24a, 24b. The first end 20 is convexly curved. The second end 22 is concavely curved. The radii of the first end 20 and the second end 22 correspond to each other to allow a scalloped end-to-end abutment. Other end shapes including straight ends may be used. The elongate ends 24a, 24b are generally straight and extend parallel to a centre line of the plate body 12. The rib arrangement 18 extends generally along a centre line of the second side 16 (cf. Figure 5) in the elongate direction, so that the laterally adjacent flat portions of the underside face are available as ground-contacting surface, to lie on the ground on either side of a narrow-trench, with the rib arrangement 18 providing an integrally moulded retainer structure to hang into the narrow-trench and resisting lateral displacement of the cover plate 10 by being positioned to come into abutment with the trench walls. The rib arrangement 18 may be located somewhat offset from the centreline if this is appropriate depending on the circumstances. The shape of the plate body 12 is an example and other shapes may be used. For instance, the first and second ends may be straight, rather than curved. One of the first end and second end may comprise a shelf structure extending longitudinally from and at a level above or underneath the plate body 12, so as to extend underneath or above an adjacent plate body when the plates are arranged in series along the length of a trench. The shelf structure may bridge a gap between two adjacent plate bodies. Viewed from an end (cf. Figure 6), along the centre line, the first side 14 of the plate body 12 comprises a central platform region 28 of generally even thickness to provide a straight surface area covering about 3/4 of the width of the plate body 12. Laterally of the central platform region 28, the plate body 12 gradually decreases in thickness towards the elongate ends 24a, 24b. On the second side 16, the rib arrangement 18 extends along the centre line, along the length of the plate body 12 between the first end 20 and the second end 22. Laterally, the rib arrangement 18 extends over about a third of the body width. The rib arrangement 18 provides an arrangement of structures to resist displacement from a narrow-trench. The body of the rib arrangement 18 may be provided by rib structures, as illustrated, with free space between rib structures, to reduce the overall mass of the trench cover plate compared to a fully solid body. Next to the rib arrangement 18, the second side 16 comprises a generally flat (underside) face. Two lips 26a, 26b extend laterally along the elongate ends 24a, 24b, the lips being angled down (angled in the direction of the second side 16) at about 45 degrees. The end view of Figure 6 also illustrates a plurality of plate-anti-slip features 25 (here: conical protrusions) distributed on the first side 14. The anti-slip features 25 may have other suitable geometry, such as ridges, ridge combinations in alternating orientation such as fishbone patterns or cruciform shapes. The anti-slip features are integral with the plate body 12.

To provide an illustration of scale, the narrow-trench cover plate 10 may be about 1 metre long in its elongate dimension, about 25 centimetres wide, and may have a plate thickness of about 8-10 millimetres (1 centimetre). The anti-slip features may protrude between 3-4 mm from the first side 14. The lips 26a, 26b may depend to about 3-4 mm below the second side 16. The rib arrangement 18 protrudes about 2 centimetres from the underside (second side 16) and may be about 7 centimetres wide, about one third of the width (here: 25 cm) of the narrow-trench cover plate. However, it will be appreciated that other geometries may be used, for instance the rib arrangement may protrude about 2-6 or more centimetres from the underside, and/or may have a width in the region of 4-15 cm, or other values depending on the narrow-trench or micro-trench. The floor plate may be shorter length and/or less wide.

Being a narrow-trench plate, the plate body 12 may be formed from moulded plastics material, such as injection-moulded plastic. The plate body 12 may be made as a single integrally moulded structure. In embodiments, the plate body 12 is made from recycled plastics material, such as recycled PVC. A narrow-trench cover plate from recycled PVC, with the above mentioned dimensions of 1 metre ^c 25 centimetres, is sturdy yet can be made to have a mass of less than 3 kg, making it suitable as a single-person lift cover plate. It will be understood that the overall mass may depend on the dimensions of the plate body and shape of the rib arrangement. Importantly, a single cover plate presents a low risk of drop injuries or back injuries due to the relatively low weight.

At the first end 20, the plate body 12 comprises an integral tab structure 30 constituting a connector pin structure. At the second end, the plate body 12 comprises an integral ring structure 40. The tab structure 30 is engageable in the ring structure 40 to provide a connector arrangement. The tab structure 30 comprises a first hole 32 suitable for receiving a fixation means such as a bolt. The plate body 12 comprises a second hole 42 suitable for receiving a fixation means such as a bolt, located on the first side 14 and within the footprint of the ring structure 40. When the tab structure 30 is positioned centrally in the ring structure 40, the first hole 32 and the second hole 42 are axially aligned, allowing two adjacent narrow-trench covers 10 to be fixed together using a bolt. For instance, the first hole 32 and the second hole 42 may be dimensioned to receive an M6 bolt.

Both the tab structure 30 and the ring structure 40 protrude in the longitudinal extension beyond the plate body 12, and are beneath the plane defined by the second side 16. Thereby, the tab structure 30 and the ring structure 40 can remain safely engaged underneath the plate bodies 12 when the adjacent plate bodies 12 are in end- to-end abutment. By having both the tab structure 30 and the ring structure 40 extending underneath their respective adjacent plate bodies, this hinders removal of a cover plate end connected to an adjacent cover plate. A cover plate 10 engaged by adjacent cover plates at both ends can practically not be lifted out of a trench without first removing an adjacent cover plate 10. This reduces the risk of tampering, bearing in mind the challenges of overseeing a temporary cover of several hundred metres in length. Compared to lengths of flexible extruded trench covers, the present plate bodies are relatively rigid, resisting a popping-out that can be observed with flexible extruded products, where a length of extruded material may flexibly pop out of a narrow trench when a person steps onto an adjacent portion of a flexible cover. The height and width of the ring structure 40 corresponds to the height of the rib arrangement 18 and the ring structure 40 can be considered a part of the retainer arrangement, although in some embodiments the ring structure 40 may have different width and/or height dimensions than the rib arrangement 18. In some embodiments, the retainer structure may be constituted by elements of the connector arrangement, e.g. by the ring structure. The ring structure 40 comprises an outer ring wall 44 that protrudes beyond the plate body 12 to be positionable underneath an adjacent cover plate, and an inner ring wall 46 underneath the plate body 12,. The ring structure 40 is open, without a floor structure between the outer ring wall 44 and the inner ring wall 46, which avoids a collection of fluids. The outer ring wall 44 comprises a vertical wall portion that is oriented perpendicularly to the plane of the second side 16. Furthermore, by being open, the ring structure 40 can be used as a handle and/or mounting location for vertical storage on racking.

The tab structure 30 has about half the width of the ring structure 40 allowing it to be moved laterally within a ring structure 40 while engaged in it. The tab structure 30 is tapered and comprises rounded front edges, which provides rotational leeway for two adjacent cover panels to rotate relative to each other while connected. As both the tab structure 30 and the ring structure 40 are located underneath the plane of the second side 16, the engagement and lateral and rotational movement can be effected without a moving part of a connector portion on the upward facing first side 14.

Figures 8 and 9 show underneath views of portions of two narrow-trench cover plates 10A and 10B, respectively. Each narrow-trench cover plate 10A and 10B corresponds to the narrow-trench cover plate 10 described above; the suffix -A being used to describe features of one plate and the suffix -B to describe features of the other plate in Figures 8 and 9, without otherwise repeating the description of these features. Figure 8 shows two plates 10A and 10B in linear end-to-end alignment, with the tab structure 30A of the cover plate 10A engaged within the ring structure 40B of the cover plate 10B. The first hole 32A is aligned with the second hole 40B (second hole 40B not shown in Figure 8), the alignment being sufficient to allow connection with a bolt if desired. Figure 9 shows the two cover plates 10A and 10B rotated relative to each other. The tapered silhouette of the tab structure 30A provides some leeway for lateral movement within the ring structure 40B, while maintaining a secure end-to-end connection resisting an attempt to laterally disconnect a cover plate. With reference to Figures 1-6 and particularly Figures 4 and 5, the tab structure 30 comprises a vertically (i.e., when placed over a trench, downward) extending wall 34, extending perpendicularly to the plane of the second side 16, providing a retainer for abutment against the vertical wall portion of the outer ring wall 44 to resist removal of the tab structure 30 from the ring structure 40 in the direction of the cover plate plane (i.e., the wall 34 prevents disconnection in the horizontal direction in which two cover plates are placed on the ground). The lower end of the vertically extending wall 34 comprises an insertion heel 36 that is rounded to facilitate slipping the tab structure 30 into and/or out of the ring structure 40, by inserting the tab structure 30 at an angle into the ring structure before tilting the cover plate to lie horizontally, with the insertion heel 36 gliding further within the ring structure 40. By way of the rounded insertion heel 36, the tab structure 30 can have a tab length, measured from the vertically extending wall 34 to the tab front edges, that corresponds practically to the inner space of the ring structure 40 between the inner ring wall 46 and the outer ring wall 44, to better resist a removal in the longitudinal direction. By way of a matched length and narrower width, the tab structure 30 has some freedom to move and swivel laterally inside the ring 40, relative to an adjacent cover panel, but is constrained in the longitudinal direction towards and away from an adjacent cover panel. Thereby, the connector arrangement allows a series of narrow-trench cover panels to follow a curved path of a narrow- trench, in the manner illustrated in Figure 9, while reducing gaps between two cover panels.

While the process of connecting two adjacent cover panels is described by inserting a tab structure 30 at an angle into the ring structure 40, the connection can be established reversely, whereby the tab structure 30 is in place horizontally over a narrow-trench, and another cover plate’s ring structure 40 is put over the tab structure 30 and tilted, such that the outer ring wall 44 glides upward over the insertion heel 36. Thereby, the arrangement allows installing and/or removing, respectively, of adjacent narrow-trench cover plates individually in both directions.

Figures 10A, 10B, 11 A, 11 B and 12 show side views of portions of two narrow-trench cover plates 10A and 10B, respectively, and are partially transparent to better show the engagement of a tab structure 30A and a ring structure 40B. Each narrow-trench cover plate 10A and 10B corresponds to the narrow-trench cover plate 10 described above; the suffix -A being used to describe features of one plate and the suffix -B to describe features of the other plate. Figures 10A and 11A show two snapshots during connection of a cover plate 10A to a previously laid down cover plate 10B. Figures 10B and 11 B show two snapshots during connection of a cover plate 10B to a previously laid down cover plate 10A. Figure 12 shows the engagement after connecting two cover plates. In Figure 10A, the tab structure 30A is inserted into the ring structure 40B, from above, and tilted down, whereby the curved insertion heel 36A avoids the tab structure 30A being wedged at an angle against the outer ring wall 44B of the ring structure 40B. In Figure 10B, the insertion heel 36A has passed the outer ring wall 44B of the ring structure 40B and the cover plate 10A is tilted further down until it lies horizontal with the cover plate 10B as shown in Figure 12. In Figure 10B, the ring structure 40B is pulled over the tab structure 30A and tilted down, the curved insertion heel 36A avoiding that the tab structure is wedged in at an angle. In Figure 11B, the outer ring wall 44B of the ring structure 40B has passed the insertion heel 36A of the tab structure 30A and the cover plate 10B is tilted further down, levering the outer ring wall 44B upward underneath the cover plate 10A, until the cover plate 10B lies horizontally with the cover plate 10A (Figure 12).

Referring now to Figures 1, 3 and 7 showing the first side 14 and a detail section, the cover plate 10 comprises a plurality of (here: 3) inserts 50a, 50b, 50c constituting high- visibility elements. The inserts 50a-c are arranged along the centre line in the elongate dimension of the cover plate, although other position arrangements may be used, and any number of inserts, such as a single insert, or 2, 3, 4, 5, 6, 7, 8, 9, 10 or more inserts may be used. As shown in Figure 3, the inserts 50a-c are equidistantly spaced apart by an inter-insert spacing. The distance between the first end and its nearest insert 50a is about half the inter-insert spacing, and the distance between the second end 22 and the nearest insert 50c is also about half the inter-insert spacing, such that equidistant insert spacing may be provided between connected narrow-trench cover plates. In some embodiments, the cover plate may comprise a single insert to provide a high-visibility element in the form of a strip extending along some or all of the length of the plate body.

Each insert 50a-c snap-fits, by way of retainer clips 52, into corresponding slots 15 (section Figure 7 showing slots 15) in seating locations 60 within the plate body 12. The inserts 50a-c are made from a material with a contrasting colour to the cover plate 10, such as yellow HDPE, to provide a high-visibility element. Other colours, such as white, orange etc., as well as reflective structures, may be used. As alternative to a snap-fit, inserts may be overmoulded or fixed using fixation means such as bolts or adhesive in order to be retained securely in the plate body 12. Preferably, any fixation means are countersunk or otherwise flush with the first face 14. Alternatively, fixation means are shaped such that any portions protruding above the first face may provide an anti-slip feature. Snap-fit arrangements allow a cover plate to be removed relatively easily for maintenance or replacement, while providing an otherwise secure seating for day-to-day use.

Advantageously, the use of one or more discrete high-visibility elements as inserts allows otherwise more environmentally friendly material, such as recycled plastics material, to be used for the main body. Underlying the present invention was an appreciation that, surprisingly, the relatively small inserts are sufficiently robust even when used on a floor plate, where they are exposed to steps or wheels by passengers or vehicles. The robustness is improved by allowing the inserts to be integrated with the main body, without creating a trip hazard, or without a practical risk of loss of, or damage to, an insert in use.

The inserts 50a-c may be provided with insert anti-slip features 54 such as ridges and protrusions, as illustrated in Figures 1 and 3.

Describing the insert 50a of Figure 7 as representative for the other inserts 50b and 50c, the insert 50a comprises a generally rectangular panel measuring about 10 cm x 7 cm and comprising a first panel face 56 and a second panel face 58. The first panel face 56 constitutes a top panel side and comprises an arrangement of insert anti-slip features 54 (anti-slip features 54 illustrated in Figure 3). The second panel face 58 on the panel underside constitutes a seating surface to lie upon a seating location of the plate body 12. The second panel face 58 comprises an arrangement of retainer clips 52a, 52b that constitute anchoring portions and are insertable into corresponding slots 15 in the plate body 12. The anchoring portions extend generally perpendicularly from the second panel face 58 to enable insertion in one direction, which facilitates assembly while providing a secure, practically permanent attachment. Other anchoring elements such as bolts may be used to provide anchoring portions. When the insert 50a is inserted in the plate body 12, the retainer clips 52a, 52b protrude through the thickness of the plate body 12 and thereby provide a firm anchoring of the insert 50a on the plate body 12. Viewed from the underside, portions of the anchoring elements (retainer clips 52a, 52b) are not concealed by the retainer structure, and therefore remain exposed on the underside at locations between the retainer structures. Being of contrasting colour, the anchoring elements thus exposed are easily visible, even though they might be within and/or between (or surrounded by) the retainer structures of the rib arrangement 18, providing a reassurance of their integrity and/or the integrity of the anchoring by quick visual inspection of the underside of the plate. The slots 15 are located within the footprint of the rib arrangement 18. Furthermore, as illustrated in Figure 7, the retainer clips 52a, 52b do not protrude below the ribs 18. Thereby, the ribs of the rib arrangement 18 provide a level of shielding, both lateral shielding and against impact from below, for the retainer clips 52a, 52b. An insert may comprise a plurality of anchoring portions, for instance more than two anchoring portions, distributed along its length. Particularly for embodiments comprising few, or a single, high-visibility element of longer dimensions, the insert may be overmoulded and/or comprise multiple anchoring elements.

The plate body 12 comprises seating locations 60 for the inserts 50a-c. A seating location 60 may be profiled corresponding to the second panel face 58 to provide a tight seating of the insert 50a. The profile of the seating location 60 may be characterised by a generally flat surface without anti-slip features that are otherwise present on the first face 14. The seating location 60 may be recessed in the manner of a socket, and may have a socket depth corresponding to the panel thickness of the insert 50a so as to avoid that the insert 50a protrudes too much above the first side 14. In embodiments, the socket may be deeper than the panel thickness, or less deep than the panel thickness. The insert 50a may have tapered edges to avoid a stepped edge. As illustrated in Figure 7, the first panel face 56 is generally level with the first side 14, such that the anti-slip features 54 of the insert 50a protrude a similar distance as the plate anti-slip features 25. Thereby, the insert 50a corresponds in silhouette to the otherwise unitary plate body 12. However, in some embodiments, portions the high- visibility element panel may protrude beyond the top plane of the plate body.

The provision of a matching abutment profile of the seating location 60 and the second panel face 58, such as a flat-on-flat engagement, reduces the strain exerted on the high-visibility element 50a when stepped on or driven over. This allows relatively larger high-visibility elements, and therefore fewer elements, to be used than might otherwise be the case. By seating the high-visibility element as much as is practical within the silhouette of plate body, trip hazards are further reduced.

One or more inserts 50a may be provided with a label or other identifier. An insert surface area such as the central area of the insert may be without anti-slip features to provide space for a label.

The plate body 12 of the dimensions and materials described above is relatively sturdy, resisting deformation. The plate body 12 may optionally be provided with elongate recesses or slots, for instance two elongate slots, providing areas of reduced rigidity separating segments of higher rigidity. In the region of the slots, the plate body 12 is more flexible while still being of unitary mould construction with the more rigid segments. Such a slot segmentation surprisingly allows a plate body to be bent in the plane of the plate body 12. Thereby, the plate body 12 can be shaped somewhat into a curved plate to better follow the contour of a small-radius curve in the narrow-trench or micro-trench. The plate body 12 may resist being curved and have a tendency to self- straighten, exhibiting some resilience that provides a better anchoring in a narrow trench.

The exemplary narrow-trench cover plate described herein is one metre long. One- metre narrow-trench plates have been found in internal trials to strike a good balance between ease of handling, sturdiness, and number of cover plates required to cover a length of narrow-trench. However, other lengths may be provided, such as half-metre floor panels. The connector arrangement allows mixing of narrow-trench cover plates of different lengths, different width, and/or different strengths, for instance for a narrow curve radius or different ground conditions.

Claims

CLAIMS:

1. A narrow-trench cover plate for temporarily covering a length of a micro-trench or of a narrow trench, the cover plate comprising a moulded plastics body providing an elongate floor plate having a top face and an underside face, the underside face comprising one or more fixed retainer structures protruding from the underside face so as to extend into a trench over which the cover plate is to be placed, wherein the cover plate further comprises one or more high-visibility elements on the top face, the high- visibility elements being of contrasting colour to the top face.

2. The narrow-trench cover plate according to claim 1, wherein the high-visibility elements are made from a plastics material.

3. The narrow-trench cover plate according to claim 1 or 2, wherein the moulded body is made from recycled plastics material.

4. The narrow-trench cover plate according to any one of the preceding claims, wherein the high-visibility elements are retained in the floor plate by being partially overmoulded.

5. The narrow-trench cover plate according to any one of the preceding claims, wherein the moulded body comprises one or more seating locations in the top face, each seating location comprising a surface profile corresponding to a seating surface of a high-visibility element.

6. The narrow-trench cover plate according to claim 5, wherein the one or more seating locations are flat, corresponding to a flat seating surface of the high-visibility elements.

7. The narrow-trench cover plate according to any one of the preceding claims, wherein an anchoring portion of a high-visibility element protrudes through the floor plate and extends beyond the underside face.

8. The narrow-trench cover plate according to any one of the preceding claims, wherein one or more anchoring portions of the high-visibility elements are within a footprint of the one or more retainer structures.

9. The narrow-trench cover plate according to any one of the preceding claims, wherein at least a portion of a high-visibility element forms part of the retainer structure.

10. The narrow-trench cover plate according to any one of the preceding claims, wherein one or more high-visibility elements comprise anti-slip features, such as a surface profile comprising anti-slip protrusions.

11. The narrow-trench cover plate according to any one of the preceding claims, further comprising an end-to-end connector arrangement comprising at one plate end a connector pin structure and at the opposite plate end a connector ring structure.

12. A narrow-trench cover plate for temporarily covering a length of a micro-trench or of a narrow-trench, the cover plate comprising a moulded plastics body providing an elongate floor plate having a top face and an underside face, the underside face comprising one or more fixed retainer structures protruding from the underside face so as to extend into a trench over which the cover plate is to be placed, wherein the cover plate further comprises an end-to-end connector arrangement, the connector arrangement comprising a connector pin structure protruding beyond the floor plate and a connector ring structure extending underneath and protruding beyond the floor plate.

13. The narrow-trench cover plate according to claim 11 or 12, wherein the connector ring structure is as wide as the one or more retainer structures.

14. The narrow-trench cover plate according to any one of claims 11 to 13, wherein the connector ring structure comprises a generally quadrilateral circumference.

15. The narrow-trench cover plate according to any one of claims 11 to 14, wherein the connector ring structure is open so as to avoid the collection of fluid.

16. The narrow-trench cover plate according to any one of claims 11 to 15, wherein the connector pin structure comprises a flat top surface extending in the plane of the underside face, to abut the underside of an adjacent cover plate.

17. The narrow-trench cover plate according to any one of claims 11 to 16, wherein the connector pin structure comprises a hole.

18. The narrow-trench cover plate according to any one of claims 11 to 17, wherein the connector pin structure comprises a wall structure extending perpendicularly downward from the underside face, a lower end of the wall structure comprising a rounded insertion heel.

19. The narrow-trench cover plate according to any one of claims 11 to 18, wherein the connector pin structure tapers laterally with increasing distance from the floor plate.

20. The narrow-trench cover plate according to any one of the preceding claims, wherein an end of the floor plate is concavely curved and the other end of the floor plate is correspondingly convexly curved so as to allow a scalloped end-to-end abutment.

21. The narrow-trench cover plate according to any one of the preceding claims, wherein the cover plate has a width at least three times the width of the retainer structure.

22. A mould for a narrow-trench cover according to any one of the preceding claims, the mould comprising one or more mould portions that provide a cavity corresponding to a generally flat cover plate with one or more fixed retainer structures and one or more seating locations for receiving a high-visibility element to be provided.