GB2351110A

GB2351110A - A method for excavating a preformed highway

Info

Publication number: GB2351110A
Application number: GB9914370A
Authority: GB
Inventors: Peter Lynes
Original assignee: SOUTH STAFFORDSHIRE GROUP PLC; SOUTH STAFFORDSHIRE WATER PLC
Current assignee: SOUTH STAFFORDSHIRE GROUP PLC; SOUTH STAFFORDSHIRE WATER PLC
Priority date: 1999-06-18
Filing date: 1999-06-18
Publication date: 2000-12-20
Anticipated expiration: 2019-06-18
Also published as: GB9914370D0; AU5689600A; WO2000079054A1; GB2351110B

Abstract

A template is used when making a hole in a highway to make it easier to restore the highway to its original level. The template is used to provide a straight cut edge following which an edge protector is put in place. A template may itself function as the edge protector. Whilst in situ the template can ensure the hole is safe without the need for a barrier by placing a scab within it's opening. It can also help workers on the hole by suppling an addisional, moveable platform over the opening or the hole. The frame may have means to position fittings in the hole. When the hole is filled the top layer may be made of a self-setting material molded in a mat-like container.

Description

2351110 HIGHWAY REPAIR The public accept with fortitude the need for the

utilities to dig holes in a highway which may be for pedestrian or vehicular traffic. Such holes are necessary to repair or replace or add to pipework and the like. Although digging a hole and then filling it in afterwards should be relatively straight forward in practice this is not so. Often the level of the treated area is not restored to its original level, and this difference in height can be inconvenient and on occasion dangerous.

In recent years the authorities have decided that not only must a road be restored to its proper level but they wW impose a financial penalty on the coiltractor who fails to comply with this requirement. Now it becomes economically important for the utility companies and their contractors to do the job properly first time to avoid such fines.

This invention is based on the realisation that because of the coarse way in which holes are formed, the task of infilling them to restore the surface to its original level is made unnecessarily difficult.

According to the invention in one aspect there is provided a method of carrying out a repair or replacement by excavation in a preformed highway, the method comprising; superimposing a template on the highway surface to define an area of surface to be removed; 2 0 cutting the perimeter of the defined area to provide substantially straight cut edges; 0 removing the top layer of the area to expose the substrate; 0 locating an edge protector in the cut out to protect the straight cut edges; 0 excavating the highway material in the cut area to the predetermined depth; 0 carrying out the required repair or replacement or the like; 0 infilling the hole to below the top level; 0 removing the edge protector; and 0 applying a self-setting material to restore the level of the excavation to its previous level.

The template may be a frame shaped to define the area to be excavated. In one simple form this is simply a border used to mark out the area, e.g. using chalk. The surface area is then cut, e.g. sawn and the material removed. In a preferred aspect the template includes a slot to receive and guide the saw.

In another aspect the invention provides for use in the method of saw cutting comprising a frame adapted to be secured to the ground to be excavated, the frame 3 having an outer horizontal ledge having slots in the ledge shaped to receive the blade of a saw to make a cut along the majority of the perimeter of the frame.

The excavation may be made in order to install or replace fittings such as a stop tap. It is an advantage of the invention that the frame includes means to position such fittings. In one preferred embodiment the means comprise a slidable plate having holes or the Eke to define the position of the fittings.

In another aspect the invention provides for use in the method an edge protector comprising a frame having substantially straight vertical walls, a ledge for a plate member being present on the inner surface of the walls.

In yet another aspect the invention provides for use in the method, one or more layers of material to be placed in the hole, the one layer or the top layer being made up of the self-setting material and being housed in a mat-like container.

In order that the invention may be well understood it will now be described by way of example only with reference to the accompanying diagrammatic drawings, in which:

Figure 1 is a perspective view of a combined template and edge protector; Figure 2 is a transverse sectional view of an excavation having an edge protector and covered by a temporary slab; 4 Figure 3 is a plan view of an excavation having an edge protector containing a movable plate; Figure 4 is a vertical section showing an infill; and Figure 5 is a sectional view of a reinstated excavation.

The frame F shown in Figures 1, 2 and 3, is generally rectangular as seen in plan and is made up of side walls 1 secured together at their ends. Each side wall comprises an upright web 2 having at its top an outwardly turned ledge 3 along its length. A shelf support 4 is present on the inside below the top to support a sliding plate 7 that allows optimum fitting of the street furniture as will be explained below. The support 4 is present at a depth corresponding to the correct thickness of the intended top infill top layer. The frame may be made of steel, plastic, fibre-glass or any other suitable material. An elongate enclosed slot 5 is present in each ledge, dimensioned to allow the blade of a power saw to pass along but this slot is optional. (In some circumstances it may be desirable to have the slot guide provided in a separate frame.) In use the frame F is first placed on the ground in the place in the highway where an excavation is to be undertaken, e.g. a substrate S having a top layer T, and where there is no slot 5 the area round the ledge of the frame is marked using chalk, crayon or other non-permanent marker. The operative then uses a powered 'floor saw' to cut cleanly along those lines where the slot is present, or the saw is passed along the slot 5 in all four sides, the frame F is removed, and the comers of the cut are joined to form a continuous cut. The area thus defined is the intended excavation. The surface layer of material is excavated from within the sawn area to a depth equal to the depth of the frame F. As soon as a sufficient depth of material is removed to allow its installation, the frame F is placed in the resultant excavation E so that it sits around the cut edge of the hole, thereby protecting the cut edges from damage as the rest of the ground is excavated to the required depth. In this way the frame acts both as the template and the edge protector. The necessary work required is then undertaken within the excavation.

Where it is not possible for reinstatement work to be undertaken immediately, the excavation E may be made safe for members of the public by leaving the excavation frame F in place and as shown in Figure 2 inserting a temporary infill slab cover 6. This slab sits on the shelf 4 inside the excavation frame, effectively bridging the excavation and allowing pedestrian (or even vehicular) traffic to pass safely over it. By suitable dimensioning the cover 6 and the height of the shelf 4 the cover will be level with the substrate. The infill slab may be made from 'checker plate' or similar steel plate, suitably strong plastic sheeting, reinforced fibreglass or, for footpath use only, from exterior plyboard. The infill sheet may have a non-slip surface and may be printed with details of who is responsible for the excavation and their contact telephone number, i.e. the Utilities Customer Contact Centre number. The cover 6 is removed when the operatives want to resume work. Because of the cover 6 barriers may not be necessary.

As shown in Figure 3, a plate 7 is arranged to slide along the ledge. The plate 7 is made of metal, plastics or the like. It has the same width as the internal width of the frame but is much shorter. The plate may be a flat web or it may have one or more depending walls. The web of the plate 7 may have a hole or mould 8 (or a 6 selection of these) to form a hole or chimney in the excavation infill for the positioning of components or other road furniture. As shown in Figure 3 the plate 7 is designed for the installation of stop-tap boxes and the hole 8 is used as a guide to ensure accurate placement of the stop tap assembly 10 prior to final reinstatement.

The plate 7 may be used to guide the operative to fill the excavation to the right level across its area, i.e. the sliding plate in the guide frame indicates not only when the correct level of backfill B has been achieved but also that the excavation is backfilled to the same level across its entire area. Once this stage is reached the frame F is removed and the excavation may be either temporarily or permanently reinstated to the original level of the highway.

Experience shows that the laying of paving slabs, requires a much lower skill level than reinstatement using loose, bituminous material and, because paving slabs are manufactured to standard thicknesses, there is less risk of incurring fines from the Local Authority's Highway's inspectors. The invention has the advantage that the reinstatement of areas requiring the use of bituminous material can be done using blocks of bituminous or other self-setting material. According to the invention, pre-formed 'mats' 20 of pre-set bituminous material are factory moulded to the thicknesses required by the New Roads and Streetworks Act, and delivered to site. These slabs will vary in thickness according to the type of road or footpath that is to be reinstated, the number, thickness and particle size of constituent layers being as dictated by the Act.

7 These mats 20 may have a hole or mould 21 to house road or footway surface furniture of metal or plastic, or may simply comprise of a solid slab of bituminous material for use where no surface furniture is to be installed. The slab is reinforced to prevent cracking and breakage during transport and handling, by a layer of non-biodegradable glass fibre mesh. This mesh is placed in or between the construction layers which make up the slab and can be bonded, using an acceptable tack coat, to the underside of each slab if several slabs are used.

The mats are manufactured to exactly the same dimensions as the excavation frame, (i.e. the size of mat brought to site will depend on the size of the excavation frame used for the job in question). On completion of the operatives work and backfill to the guided, (legally required) level the frame F can be removed from the hole and a tack coat applied to the surface and edges of the excavation. The reinstatement mat is then carefully placed in the excavation and either a vibrating roller or plate used to 'bed in'the mat. Any slight gaps may then be filled using a proprietary bituminous mastic.

Frames of different strengths may be produced for different situations, i. e. a thinner, less robust frame of, say 3 mm section steel, might be used in the footpath where a thicker section might pose a trip hazard, whilst a stronger, heavier frame of, say, 6 mm section, might be used in the roadway. The leading edges of all frames are chamfered to reduce them to less than the legally acceptable 'trip hazard' of 6 mm.

The invention is not limited to the embodiment shown. The saw slots 5 may be omitted, in which case the frame F is removed once the area has been marked out 8 and the perimeter of the area is cut. The plate need not be present on all four sides. The frame need not be rectangular. The frame may be hinged for compactness in storage and transport. The top layer may be filled in using loose material. The excavation will typically be in pedestrian footpath but it could be anywhere.

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Claims

A method of carrying out a repair or replacement by excavation in a preformed highway, the method comprising; superimposing a template on the highway surface to defime an area of surface to be removed; cutting the perimeter of the defined area to provide straight cut edges; removing the top layer of the area to expose the substrate; locating an edge protector in the cut out to protect the straight cut edges; excavating the highway material in the cut area to the predetermined depth; carrying out the required repair or replacement or the like; infilling the hole to below the top level; removing the edge protector; and applying a self-setting material to restore the level of the excavation to its previous level.
2. A method according to Claim 1, wherein the template and the edge protector are a single or separate piece of apparatus.
3. A method according to Claim 2, wherein the apparatus comprises a frame having straight vertical walls.
4. A method according to Claim 3, wherein the apparatus has an outer horizontal ledge dimensioned to overlie the perimeter of the cut hole.
5. A method according to Claim 4, wherein the frame has slots in the ledge shaped to receive the blade of a saw to make a cut along at least some of the perimeter whereby the frame acts as the template.
6. A method according to Claim 3,4 or 5, wherein the inner vertical walls of the frame have a ledge for a plate member.
7. A method according to Claim 6, wherein the inner ledge can receive a guide plate that is at a level to which the excavation can be backfilled less the top layer.
8. A method according to Claim 7, wherein the plate to be located on the ledge contains a mould to form a passageway for apparatus or fitting in the hole to be exposed on the highway.
9. A method according to Claim 6, 7 or 8, wherein the plate is arranged to be slidable along the ledge.

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10. A method according to any of Claims 6 to 9, including the step of temporarily locating a slab on the ledge in an interval between work periods, the slab being shaped and dimensioned to raise the level of the hole to match that of the surrounding highway surface.
11. A method according to any preceding Claim, including the step of locating one or more layers of material in the hole, the one layer or the top layer being made up of the self-setting material whereby the level of the material is matched to that of the surrounding highway surface.
12. A method according to Claim 11, wherein the or each layer is in the form of a mat.
13. A method according to Claim 12, wherein the mat includes a mould to form a passageway dimensioned to allow apparatus or fitting in the hole to protrude through to the highway surface.
14. A method according to any preceding Claim, wherein the self-setting material is applied hot or cold.
15. For use in a method according to any preceding claim a frame having straight vertical walls, the frame having an outer horizontal ledge, the ledge having slots in the ledge shaped to receive the blade of a saw to make a cut along some of the perimeter of the frame.

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16. For use in a method according to any of Claims 1 to 14, a frame having straight vertical walls, a ledge for a plate member being present on the inner surface of the walls.
17. For use in a method according to any of Claims 1 to 14, a slidable plate having means therein to position fittings to be located in the excavation.
18. For use in a method according to any of Claims 1 to 14, one or more layers of material to be placed in the hole, the one layer or the top layer being made up of the self-setting material and being housed in a mat like container.

LS/VMS/JW/ 14.06.99 P02497 GB.de