In recent years the authorities have decided that not only must a road be restored to its proper level but they will impose a financial penalty on the contractor 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: parking out the area of the highway to be excavated; emoving the top layer of the area to expose the substrate; excavating the substrate material in the cut area to the predetermined depth; carrying out the repair or replacement; infilling the excavation; and applying a self-setting material; characterised by superimposing a template on the highway surface to define straight edges of the area to be cut, and locating an edge protector in the cut area to protect the straight cut edges until infilling of the hole is complete.

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 a frame for use in the method, the frame having straight wide walls to be vertical in use, the frame having an outer horizontal ledge, the ledge having slots shaped to receive the blade of a saw to make a cut along some 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 like to define the position of the fittings.

In another aspect the invention provides for use in the method of a mat containing self- setting material.

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; 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 (Fig. 3) 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 corners 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 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 4. 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 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 a fine or penalty 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 and as shown in Figure 5, pre-formed'mats'20 of pre-set bituminous material are factory moulded to the thicknesses required by the United Kingdom New Roads and Streetworks Act, or an equivalent, 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.

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 installe. 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 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.