GB2262299A

GB2262299A - Depth indicator for use in the repair of road surfaces

Info

Publication number: GB2262299A
Application number: GB9126576A
Authority: GB
Inventors: Alan Singleton
Original assignee: Yorkshire Electricity Group PLC
Current assignee: Yorkshire Electricity Group PLC
Priority date: 1991-12-14
Filing date: 1991-12-14
Publication date: 1993-06-16
Also published as: GB9126576D0

Abstract

A method for the reinstatement of a highway surface following its excavation, comprises inserting into the excavation a depth indicating means having depth markers thereon to indicate appropriate depth levels below the top of the highway surface to which appropriate types of filling agent are to be used to fill the excavation; and filing the excavation, with the depth indicating means still in position inside it, with each appropriate filling agent up to the level of its respective depth marker. The method is simpler to use than existing techniques, and does not require the separate calculation of appropriate depths and thicknesses, or compensation for an excavation the bottom of which is not parallel to the top surface of the highway along its entire length. The invention also provides a depth indicating means for use in the method.

Description

REINSTATEMENT OF HIGHWAY SURFACES Field of the Invention This invention relates to a method for reinstatement of a highway surface following its excavation, and to a depth indicator for use in such a method.

Background to the Invention The construction of roads and footways is at present regulated by local highway authorities. Although most are constructed along similar themes, all tend to differ in either the materials used for construction or the layer thicknesses of those materials.

Any utility, such as a supplier of electricity or gas, which excavates a road or footway currently bears the responsibility for making a temporary repair to its surface (with the exception of some local model agreenents). The local highway authority will then remove the temporary reinstatement at a later date and replace it with a permanent construction.

The New Roads and Street Works Act 1991, which comes into force in 1992, shifts the responsibility for reinstating an excavation of a highway to the utility which carries out the excavation. A national specification has been issued, to which all such reinstatements must conform.

For the first time, all reinstatements in this country will need to be carried out to the same specification.

The specification stipulates the materials with which a highway excavation must be reinstated, and to what depth below the top surface of the highway each layer of a particular filler material must be used. For instance, a top layer of a hard wearing material will be required to extend to a certain depth below the top surface of the highway. Below this, an intermediate layer of a less hard wearing material will typically be required, again of a specified depth. Below this, a sub-base of a granular material, again with its depth specified, will usually be needed.

For excavations deeper than the sum of the specified layer depths, the remaining depth of the excavation will typically be filled in with sand and classified backfill material.

Every utility will now have either to train its own staff, or to employ specially trained contractors (who will also have to follow the new national specification) to reinstate its highway excavations. All the reinstatements will have to comply with the performance criteria given in the specification. Any failing within specified guarantee periods will have to be reconstructed, at the expense of the utility concerned.

The main problem with any specification for a highway reinstatement is that all depth measurements, for each layer of filler material, must be taken from the top surface of the highway downwards. This is because whilst excavations may be of a wide range of different depths, it is only those layers of filler material closest to the top surface of the highway which are important in the reinstatement process.

There is no way round the need to take depth measurements from the top surface of the highway. The level of each layer of filler material, both before and after compaction, has to be separately measured and calculated from the top surface when reinstating an excavation.

Especially important are the thickness and compaction of the lower layer, since this forms a base for the whole of the upper construction of the highway.

Presently used methods for highway reinstatement tend to involve using tape measures to measure layer depths from the top surface of the highway. The correct depths and thicknesses of the lower layers must be calculated, usually with constant reference to written specifications. Reinstatement is especially difficult on longer excavation routes, where the bottom of an excavated trench may not be parallel to the top surface of the highway along its entire length. Often, a worker would need to stand inside an excavated trench so as more easily to measure depths downwardly from the top surface of the highway.

The new, more stringent, rules on the construction of highway reinstatements and their performance criteria are likely to pose problems for anyone involved in reinstatement. This will particularly be the case in the early years of the New Roads and Street Works Act 1991, when new personnel will be tackling the work involved.

Statement of the Invention According to the present invention there is provided a method for reinstatement of a highway surface following its excavation, comprising the steps of inserting into the excavation a depth indicating means having depth markers thereon to indicate appropriate depth levels below the top of the highway surface when the depth indicating means is inserted in the excavation, each depth marker corresponding to the level below the top of the highway surface to which a respective appropriate type of filling agent is to be used to fill the excavation; and filling the excavation, with the depth indicating means still in position inside the excavation, with each appropriate filling agent up to the level of its respective depth marker on the depth indicating means.

The method of the invention is relatively simple and cheap to use. It does not require constant referral to documents, since the appropriate depth levels for each filling agent are marked on the depth indicating means.

Nor does it require the separate calculation of appropriate depths and thicknesses, or compensation for long excavations in which the bottom of the excavation is not parallel to the top surface of the highway along its entire length.

By highway is meant any road or footway, the surface of which needs to be reinstated following excavation. The highway may be of the flexible type (as are most everyday types of road or footpath) or of the rigid, for instance concrete, type. However, the method of the invention is most suitable for use in reinstatement of flexible highway types, such as type one flexible roads (major highways and motorways), type two flexible roads (major A roads), type three flexible roads (B roads), type four flexible roads (eg housing estate roads) or flexible footways.

The excavation may take the form of a trench of any length. A series of depth indicating means may be used in the method, at appropriate positions along the length of the excavation. This will allow reinstatement of the excavation with filling agents to the appropriate levels along its entire length, the layers of filling agents remaining parallel to the top surface of the highway. In the case of long excavations, where the bottom of the excavation does not always run parallel to the top surface of the highway, the use of a series of depth indicating means in accordance with the method of the invention is particularly advantageous.

The depth indicating means may be in the form of a tape or string, or of a rigid ruler made, for instance, from steel or wood. It preferably comprises a tape of an appropriate length, more preferably a flexible plastics tape. Ideally, the plastics material from which the tape is made is bio-degradable. The tape can then be left in the reinstated excavation, without risk of environmental pollution.

The depth markers will conveniently take the form of visual indications printed on the depth indicating means.

Alternatively, they may comprise notches or grooves appropriately positioned on a rigid ruler or other depth indicating means. The positions of the depth markers will depend on the exact type of highway whose surface is to be reinstated.

The filling agents with which the excavation is filled will be chosen according to the particular type of highway whose surface is to be reinstated, and will normally be specified in appropriate legislation.

The depth indicating means may also be provided with submarkers indicating appropriate compaction depths for filling agents to be used between the levels of the depth markers. The method of the invention thus preferably also includes compacting one or more of the filling agents to an appropriate extent when using that agent to fill the excavation, using the sub-markers on the depth indicating means as a guide to the depths at which the agent is to be compacted.

The depth indicating means is preferably inserted into the excavation so that a first depth marker on the depth indicating means lies level with the top of the highway surface. It may be secured in place inside the excavation by any suitable means. Preferably, anchoring means are provided with the depth indicating means for this purpose. For instance, a depth indicating means having the form of a flexible tape may be draped into the excavation so that a top portion of the tape remains outside the excavation, lying along the surface of the highway. This top portion may be clamped in position against the highway surface.

The present invention additionally provides a depth indicator for use in a method for reinstatement of a highway surface following its excavation, the indicator comprising an elongate body capable of being inserted into the excavation, and the body having depth markers thereon to indicate appropriate depth levels below the top of the highway surface when the depth indicator is inserted in the excavation, each depth marker corresponding to the level below the top of the highway surface to which a respective appropriate type of filling agent is to be used to fill the excavation.

The elongate body may be flexible (eg made from tape or string) or rigid (eg a steel or wooden ruler). It preferably comprises an elongate flexible tape, preferably made from a bio-degradable material, typically a plastics material. Conveniently, such a tape will be approximately three inches wide. The depth markers on the depth indicator may be printed on its surface or may comprise notches or grooves at appropriate points along it. Regions between the depth markers are preferably marked so as to indicate an appropriate type of filling agent to be used to reinstate an excavation between the depth levels indicated by the depth markers. Such markings may comprise, for instance, written labels, or regions of shading or hatching or other pictorial representations of the type of filling agent to be used between two depth markers.

The positions of the depth markers on the depth indicator, and the information as to appropriate types of filling agents to be used between the depth markers, will vary according to the exact type of highway surface to be reinstated using the depth indicator. A different depth indicator, with appropriate markings thereon, will therefore be needed in the reinstatement of each different type of highway surface.

The depth indicator preferably has a top depth marker on it, which when the depth indicator is inserted into an excavation may be arranged to lie level with the top surface cf the excavated highway. This indicates the uppermost level to which the excavation needs to be filled with filling agents.

The depth indicator may include additional information.

This may include, for instance, a key to shading or other pictorial representations used between the depth markers; and full instructions as to the types of filling agent to use in method of reinstatement of a highway surface and as to how to apply those filling agents to an excavation.

Such additional information is preferably included on the depth indicator above the level of the top depth marker.

The depth indicator preferably additionally comprises anchoring means, by which it may be secured in place inside an excavation. Where the depth indicator is in the form of a flexible tape, this anchoring means may simply comprise an upper portion of the tape, above the top depth marker, which when the depth indicator is inserted in an excavation remains draped over the top edge of the excavation, along the surface of the highway.

This upper portion may then be clamped in position against the highway surface by any appropriate means.

The present invention will now be described, by way of example only, with reference to the accompanying illustrative drawings, of which: Figures 1 and 2 show a depth indicator in accordance with the present invention; and Figures 3-5 show an alternative depth indicator in accordance with the invention.

Detailed Description of the Drawings The depth indicator shown in Figures 1 and 2 has the form of an elongate flexible tape 1, around three inches wide, made from a bio-degradable plastics material. The tape is in fact continuous, Figure 2 showing its continuation from Figure 1. The full length of the tape is not critical and will depend on the particular use to which it is to be put.

The tape 1 is for use in a method of reinstatement of the surface of a type three flexible road (ie a typical B road in the UK) in accordance with the invention. It is marked with two major depth markers, 2 and 3. Marker 2 is the top depth marker, which, when the tape 1 is inserted into an excavation, should lie level with the top surface of the excavated highway.

Depth marker 3 indicates the level, below the top surface of the highway, down to which an upper layer of a dense wearing filling agent (such as course macadam of Gmm size) must be used to fill an excavation when reinstating a type three flexible road. The region 4 between depth markers 2 and 3 is filled in so as to indicate pictorially the type of filling agent to be used between the two depth levels.

A third depth marker, 5, is provided on tape 1 in a series of steps, A, B, C and D. These indicate appropriate levels, below the top surface of the highway to be reinstated, down to which a second type of filling agent (typically a dense base course macadam of 2 Omm size) should be used to reinstate an excavation in the highway surface. Again, the region 6 between depth markers 3 and 5 is shaded so as to provide a pictorial indication of the type of filling agent to be used between these two levels.

Below depth marker 5, region 7 of the tape represents the region of an excavation which may be filled in with a backfill agent and surround (typically sand and classified backfill material). This final type of filling agent may usually be employed from the level of depth marker 5 right down to the bottom of an excavation.

The separate levels A, B, C and D of depth marker 5 are for use with four different classes of backfill which may be used to reinstate an excavation. The class to be used in any particular case is determined by on-site testing of material removed from the excavation, for moisture or clay content.

The upper portion 8 of the tape 1 includes various information as to the type of filling agents to be used with the tape and how best to apply them to an excavation. This information includes a key to the shading used in regions 4 and 6 of the tape, to indicate the appropriate types of filling agents to be used between the depth markers 2, 3 and 5.

All information and markings are printed on the tape.

In use in a method in accordance with the invention, the tape 1 is inserted into an excavation in a highway surface, such that its upper portion 8 is draped over the top edge of the excavation and lies against the highway surface. Portion 8 of the tape may then be clamped in position, for instance under a heavy weight, to ensure that the tape remains correctly positioned inside the excavation.

With tape 1 still in place inside the excavation, a filling agent such as sand and classified backfill material is used to fill the excavation up to the level of depth marker 5 (to level A, B, C or D, as appropriate) on the tape. An intermediate layer of a dense base course macadam (20mm size) is then used to fill the excavation up to the level of depth marker 3. Finally, an upper layer of dense wearing coarse macadam (6mm size) is applied up to the level of depth marker 2, which corresponds to the top surface of the highway.

The upper portion 8 of the tape may then be cut away.

The remainder of the tape is now out of sight inside the reinstated excavation. Because it is bio-degradable, it does not matter that the tape is left in the highway surface following reinstatement.

For a long excavation, a series of tapes such as 1 will be inserted at appropriate points along its length, for instance at roughly lOm intervals. These are then used to ensure that, even if the bottom of the excavation is not completely parallel to the top surface of the highway, the excavation can nevertheless be filled in to the correct depth (below the top surface) along its entire length.

The depth markers, and recommendations for suitable filling agents, marked on the tape 1 correspond to national specifications for the reinstatement of a type three flexible road. Use of the tape in reinstating such a highway surface therefore ensures that the reinstatement complies with national standards. Its use is simple and effective. There is no need to constantly refer to specifications and other documents, or for a user to stand inside the excavation itself and, using a tape measure, to measure and calculate appropriate depths and layer thicknesses. Reinstatements can thus be kept to a high standard, within nationally laid down specifications. Moreover the tape itself is relatively simple and inexpensive to manufacture.

The depth indicator illustrated in Figures 3-5 also comprises an elongate flexible tape 10 of a biodegradable plastics material. Figure 4 shows the continuation of the tape from Figure 3; Figure 5 shows its continuation from Figure 4. The tape is for use with an alternative type of construction for reinstatement of a type three flexible road. The choice between the construction type shown on the tape of Figures 1 and 2, and that shown on the tape of Figures 3-5, will depend on the availability and cost of materials in any particular case.

Depth markers 11, 12, 13 and 14 are printed on tape 10.

11 is the top depth marker, which when the tape is in use lies parallel to the top surface of a highway to be reinstated. Regions 15, 16 and 17 of the tape, between the depth markers, are appropriately shaded so as to represent the types of filling agent to be used in these regions. For instance, in region 15, an upper layer of a dense wearing coarse macadam (6mm size) should be used; in region 16 a dense base coarse macadam (20 mm size) should be used as a filling agent; and in region 17, a granular sub base (DTp type 1) should be used. Below the level of depth marker 14 down to the bottom of an excavation (ie, region 18 of the tape 10), a simple backfill and surround material is used.Naturally, the filling agents will be applied to the excavation from the bottom upwards, starting with the backfill and surround, proceeding to the sub-base up to the level of depth marker 13, then the 20mm macadam up to the level of depth marker 12 and finally the upper layer of 6mm macadam up to the top surface of the highway.

Depth marker 14 again has four different levels A, B, C and D, which correspond to different classes of backfill which may be used in region 18 of the tape.

The tape 10 has an upper portion 19, on which is printed information about the types of filling agent to be used with the tape and how to apply them to an excavation.

Upper portion 19 is the region of the tape which will remain outside an excavation in use, and may be clamped to the highway surface to retain the tape in position in the excavation.

On both tapes, 1 and 10, sub-markers 21 are provided at intervals, in region 6 on tape 1 and in region 17 on tape 10. This assists a user in obtaining the correct compaction of filling agents used in these regions. Each layer of filling agent can be added to an excavation and compacted to the correct extent before adding more filling agent. This is extremely helpful to the user, since the national specification for highway reinstatements stipulates that filling agents must be compacted in layers of a specific depth (e.g. 60mm for the filling agent used in region 6 on tape 1, lOOmm for that used in region 17 on tape 10).

Claims

1. A method for reinstatement of a highway surface following its excavation, comprising the steps of inserting into the excavation a depth indicating means having depth markers thereon to indicate appropriate depth levels below the top of the highway surface when the depth indicating means is inserted in the excavation, each depth marker corresponding to the level below the top of the highway surface to which a respective appropriate type of filling agent is to be used to fill the excavation; and filling the excavation, with the depth indicating means still in position inside the excavation, with each appropriate filling agent up to the level of its respective depth marker on the depth indicating means.

2. A method according to Claim 1, wherein the highway surface is of the flexible type.

3. A method according to Claim 1 or Claim 2, wherein a series of depth indicating means is inserted into the excavation at appropriate positions along its length.

4. A method according to any one of the preceding claims, wherein the depth indicating means comprises a tape of an appropriate length.

5. A method according to Claim 4, wherein the tape is a flexible plastics tape.

6. A method according to any one of the preceding claims, wherein the material from which the depth indicating means is made is bio-degradable.

7. A method according to any one of the preceding claims, wherein the depth markers take the form of visual indications printed on the depth indicating means.

8. A method according to any one of the preceding claims, wherein the depth markers comprise notches or grooves appropriately positioned on the depth indicating means.

9. A method according to any one of the preceding claims, wherein the depth indicating means is provided with sub markers indicating appropriate compaction depths for filling agents to be used between the levels of the depth markers.

10. A method according to Claim 9, additionally comprising the step of compacting one or more of the filling agents to an appropriate extent when using that agent to fill the excavation, using the sub-markers on the depth indicating means as a guide to the depth at which the agent is to be compacted.

11. A method according to any one of the preceding claims, wherein the depth indicating means is inserted into the excavation so that a first depth marker on the depth indicating means lies level with the top of the highway surface.

12. A method according to any one of the preceding claims, wherein the depth indicating means is secured in place inside the excavation.

13. A method according to Claim 12, wherein the depth indicating means is inserted into the excavation in such a manner that a top portion of the depth indicating means remains outside the excavation, which top portion is clamped in position against the highway surface.

14. A method for reinstatement of a highway surface following its excavation, the method being substantially as herein described with reference to the accompanying illustrative drawings.

15. A depth indicator for use in a method for reinstatement of a highway surface following its excavation, the indicator comprising an elongate body capable of being inserted into the excavation, and the body having depth markers thereon to indicate appropriate depth levels below the top of the highway surface when the depth indicator is inserted in the excavation, each depth marker corresponding to the level below the top of the highway surface to which a respective appropriate type of filling agent is to be used to fill the excavation.

16. A depth indicator according to Claim 15, wherein the elongate body is flexible.

17. A depth indicator according to Claim 16, which comprises a flexible plastics tape.

18. A depth indicator according to Claim 17, wherein the tape is approximately three inches wide.

19. A depth indicator according to any one of Claims 15-18, made from a bio-degradable material.

20. A depth indicator according to any one of Claims 15-19, wherein the depth markers are printed on the surface of the elongate body.

21. A depth indicator according to any one of Claims 15-20, wherein the depth markers comprise notches or grooves at appropriate points along the elongate body.

22. A depth indicator according to any one of Claims 15-21, wherein regions between the depth markers are marked so as to indicate an appropriate type of filling agent to be used to reinstate an excavation between the depth levels indicated by the depth markers.

23. A depth indicator according to Claim 22, wherein the regions are marked with pictorial representations of the type of filling agent to be used between the depth markers.

24. A depth indicator according to any one of Claims 15-23, having a top depth marker thereon, which when the depth indicator is inserted into an excavation may be arranged to lie level with the top surface of the excavated highway and indicates the uppermost level to which the excavation needs to be filled with filling agents.

25. A depth indicator according to any one of Claims 15-24, additionally including instructions as to the types of filling agent to use in a method of reinstatement of a highway surface using the depth indicator.

26. A depth indicator according to Claim 24 and Claim 25, wherein the instructions are included on the depth indicator above the level of the top depth marker.

27. A depth indicator according to any one of Claims 15-26, additionally comprising anchoring means, by which the indicator may be secured in place inside an excavation.

28. A depth indicator according to Claim 16 and Claim 27, wherein the anchoring means comprises an upper portion of the indicator above any top depth marker included on the indicator, which upper portion, when the depth indicator is inserted in an excavation, remains draped over the top edge of the excavation, along the surface of the highway.

29. A depth indicator according to Claim 28, in combination with clamping means for clamping the upper portion of the indicator in position against the highway surface.

30. A depth indicator for use in a method for reinstatement of a highway surface following its excavation, the indicator being substantially as herein described with reference to the accompanying illustrative drawings.

31. A method for reinstatement of a highway surface following its excavation, the method comprising the use of a depth indicator according to any one of Claims 15 30.