Appendix A12 Reinstatement of Modular Surface Layer

A12.1 Interim Reinstatement

Where an interim reinstatement is required, the existing modules should be reused, including the use of broken modules. Where damage has resulted in fragmentation or widespread breakage of modules [subject to the special case of natural material modules (as set out in Appendix A12.2.2)], then bituminous mixtures may be used for interim reinstatement, provided they meet the performance requirements of Section S2 and that compaction of such mixtures does not result in further damage to adjacent modules.

A12.2 Permanent Reinstatement

A12.2.1 General

1) Permanent reinstatement of modular surface layers should be generally carried out in accordance with BS 7533.

2) Permanent reinstatement of modules shall include all modules, which are situated within or extend beyond the effective width of the reinstatement (W) described in Section S2.1.4 and shall also include any other modules which are disturbed in the course of carrying out the excavation or reinstatement.

3) Clean undamaged modules shall be re-used for permanent reinstatement; broken modules shall not be used for permanent reinstatement and shall be replaced.

4) Laying course material shall be sand or mortar, to match the characteristics of the existing type and thickness. Unless otherwise notified by the Authority, where sand is present, laying course and jointing materials shall be in accordance with BS7533: Part 3. For all roads and footways, the grading of the laying course material shall be in accordance with Table D.3 Category II. Jointing materials to Section D1.2, shall be applied to gaps between individual modules at the time of permanent reinstatement. Where mortar has been used for laying course material the Undertaker shall seek guidance from the Authority as to the specification to be used. This information shall not be unreasonably withheld.

A12.2.2 Requirements for Natural Material Modules

A12.2.2.1 General for whole Natural Material Modules

The reinstatement of whole natural material modules shall be in accordance with the general requirements of Appendix A12.2.1.

A12.2.2.2 Damaged Natural Material Modules

1) Broken modules shall not be used for permanent reinstatement. Where damaged modules are to be re-used in the reinstatement, the Undertaker should take photographic records prior to commencing work. A joint inspection shall be arranged, to agree the extent of usage of damage modules and the maximum damage acceptable for re-use. This should preferably take place prior to the commencement of excavation, but must take place prior to reinstatement commencing.

2) The Undertaker shall use its best endeavours to match existing profiles and meet the tolerances specified in Section S2. However, where the pre-existing profile of damaged modules is near or in excess of current intervention and construction tolerances specified in Section S2, it will be difficult for the Undertaker to construct a complying reinstatement. The Undertaker shall use its best endeavours to ensure that the interface between its reinstatement and the adjoining surfaces avoid creating hazardous trips.

A12.2.3 Infills in Modular Reinstatements

A12.2.3.1 General

1) Gaps greater than 5mm between the nearest module and the immediately adjacent fixed feature (such as edgings, channel blocks, drainage features, surface boxes, ironware) or boundary feature (such as walls, fences and the like), which are caused as a direct result of any works by the Undertaker, should be filled to the full depth of the adjacent paving module, as follows:

(a) for smaller gaps, or infills - a 1:4 cement: sand mortar should be used;

(b) for larger gaps or infills, where aggregate can be used - a 1:5:3 cement:sand:aggregate concrete infill should be used, with a maximum aggregate size of 10 mm.

2) Infills should be generally as small as possible, subject to the proviso that where the physical characteristics of the bond, fixed feature, or proximity of other fixed features do not allow for a small infill, then best endeavours should be used to achieve the smallest infill possible.

3) Infills should match existing work by the Authority.

A12.2.3.2 Infill Widths and Limitations

1) Where possible, infills should be limited to a maximum width of 50mm in all modular areas, irrespective of whether the existing footway area was originally constructed in accordance with BS7533.

2) In the case of modules where one side of the module is greater than 300mm, there are instances where it shall be permissible to increase the width of the infill to a maximum of 150mm, in order to achieve a better engineering and aesthetically pleasing reinstatement. These include instances where the intervening distance is less than 150mm:

(a) between the Undertaker's newly laid apparatus and the nearest module (on any side), or

(b) between two or more pieces of Undertaker's newly laid apparatus, or

Where it can be shown to be acceptable custom and practice, in exceptional cases, the maximum permissible infill width may be increased to 200mm, for irregularly shaped apparatus. Typical examples are in Notes for Guidance Section NGA12.

3) In the case of modules where all sides are 300mm or less, there are similarly instances where it is permissible to increase the width of the infill to the same as the full width of module (measured on the shortest side), again in order to achieve a better engineering and aesthetically pleasing reinstatement. These include instances where the intervening distance is less than the full width of a module plus 25mm (measured on the shortest side):

(a) between the Undertaker's newly laid apparatus and the nearest module (on any side), or

(b) between two or more pieces of Undertaker's newly laid apparatus, or

Typical examples are in Notes for Guidance Section NGA12.

A12.2.3.3 Acceptable localised loss of Modular Pattern

1) Physical characteristics may prevent or limit the possibility of completing a uniform and closely matching modular reinstatement immediately adjacent to features. The physical characteristics of the module itself, the existing as-laid bond, as well as the physical characteristics of the fixed or boundary feature, may individually or collectively contribute to such a situation.

2) In all instances, the Undertaker should attempt to minimise the width of the infill. However, the following exceptions are permissible:

(a) Where the above physical characteristics are present, permanently reinstated modules immediately adjacent to the feature may be laid with a degree of localised loss of bond pattern. The introduction of a stringer (or in some cases, soldier) course immediately adjacent to the feature should not be considered as a loss of bond pattern. The loss of bond pattern should be limited, where practicable, to the first two rows beyond any stringer course, being laid in such a manner as to aesthetically integrate with the surrounded bond pattern. Typical examples are indicated in Notes for Guidance Section NGA12.

(b) If adjacent modules abut an existing, contiguous infill, such as at a property boundary, then the infill shall match the existing.

(c) In the case of fixed features that are not rectangular, there is no requirement to cut modules to match the edge profile of the fixed feature to otherwise reduce the infill at irregular edges.

(d) Where localised custom and practice adopted by the Authority for its own works differs to the above, infills may be laid to a standard consistent with that of the Authority.

A12.3 Provision of Replacement Modules

1) Where insufficient modules remain for reinstatement use and procurement of identical replacement modules is no longer reasonably practicable, then a similar colour, shape and size shall be the preferred order of criteria in the choice of acceptable replacements.

2) Where replacements modules are required due to breakages caused during the course of the Undertaker's works, the Undertaker shall reinstate using modules purchased at the Undertaker's expense. These may be purchased from the Authority at reasonable cost where available.

A12.4 Pre-existing Surface Damage outside limits of Undertaker's Works

1) Some pre-existing modular surfaces outside the limits of the Undertaker's works may be broken or have settled or deformed. Where the existing profiles are near or exceed the current intervention and construction tolerances specified in Section S2, it will be difficult for the Undertaker to construct a complying reinstatement. Subject to the Authority agreeing to meet the costs of the works necessary to reinstate the surfaces outside the limits of its works, the Undertaker shall extend its reinstatement works to include such surfaces. In the absence of agreement, the Undertaker shall be under no obligation whatsoever to extend its reinstatement works but shall use its best endeavours to ensure that the interface between its reinstatement and the adjoining surfaces avoid creating hazardous trips. In such situations, it must be recognised that it may be necessary to install different sized modules or fillets to minimise surface irregularities at the interfaces. The Undertaker shall use its best endeavours to match existing materials and profiles and meet the tolerances specified in Section S2.

2) Where the area of permanent reinstatement needs to be substantially extended, to include an existing area of broken or settled modular surfacing, the Undertaker shall notify the Authority prior to the commencement of works. see NGA 12.5 (2)