The Scottish Government

« Previous | Contents | Next »

Listen

SPECIFICATION FOR THE REINSTATEMENT OF OPENINGS IN ROADS

Notes For Guidance

NG1 Introduction

NG1.1 General

1) The primary objectives of this Specification are to ensure that all Undertakers reinstatements, within roads, are completed to a permanent standard, as soon as is practicable and of a consistent high quality. Undertakers and Authority personnel should work together, in close co-operation, in order to achieve these objectives.

2) This Specification may require a joint inspection of any reinstatement site, depending on the existing site conditions, before the commencement of works. Such joint pre-inspections may be of an informal nature, by agreement, and should be carried out at the earliest convenience of both parties. Where either party fails to attend any agreed pre-inspection, or where existing site conditions warrant concern, it is recommended that the Undertaker retains a photographic record of the existing surfaces, prior to the commencement of works.

3) This Specification may require a formal notification of circumstances or other requirements, depending on the existing conditions of any reinstatement site, prior to the commencement of works. Such pre-notifications should be issued at the earliest possible opportunity. Undertakers shall comply with such notification issued at the road works notice stage, and should make reasonable efforts to comply with any notification issued thereafter.

4) Where this Specification allows several options, it is recommended, wherever practicable, to agree a preferred option from the alternatives available. This principle should be applied to all sections where alternatives are provided.

NG1.2 Guarantee Period

1) Where an Authority intends to resurface or reconstruct a section of road, the Undertaker may complete any reinstatement to an alternative interim standard, by agreement. The guarantee period shall thereafter be waived, unless the Undertaker's reinstatement can be shown to be grossly substandard. It is expected that agreement to this procedure will be conditional upon all savings in costs made by not carrying out a permanent reinstatement being shared, equally, between the Undertaker and the Authority.

2) Where site circumstances are considered to mitigate against a successful permanent reinstatement, an additional interim period of up to a further 6 months may be adopted, before it is necessary to complete the permanent reinstatement.

NG1.3 Road Categories

1) Road categories 0 to 4 are based on the number of millions of standard axles (msa) carried by the road over a 20 year period to a critical condition. Reinstatements are designed on this basis in accordance with national pavement design standards as follows:.

a) Roads Type 0 & 1 - DoT HD 24/96
b) Roads Type 2 - Intermediate between HD 24/96 & LR1132
c) Roads Type 3 & 4 - TRRL LR1132 or TRRL RR 87

Some roads that have been constructed in recent years (particularly new housing estate roads constructed under the auspices of Section 21 of the Roads Scotland Act 1984 may have been designed and constructed to DOT HD/24/96 standards. In these cases the Authority shall notify the Undertaker, in advance of the works, and the Undertaker shall reinstate the excavation to match the existing construction thicknesses.

2) For any road, its msa rating gives the number of standard axle loads which it is expected to carry over a defined period of time. This msa rating is calculated using the following input data:

a) 24 hour annual average daily flow (AADF) of commercial vehicles in one direction. The use of one directional AADF data, averaged from two directional data, is recommended.
b) Average vehicle axle factor over a 20 year service life.
c) Actual sustained annual growth rate of commercial vehicles, averaged over several years, from valid census data

This data, processed in accordance with DoT HD 24/96 procedures, provides the maximum number of commercial vehicles per day, in each direction, for all road types. Table NG1.1 has been prepared in accordance with HD 24/96, showing the maximum annual average daily flow (AADF) in one direction, in commercial vehicles per day (cvd), for a single carriageway road, or for both lanes of a dual carriageway, for all road types, from 2002 onwards, for all likely traffic growth rates. Appropriate AADF rates for all Intermediate years within each five year period can be calculated by interpolation, pro rata.

Table NG1.1 - Maximum Commercial Vehicle Traffic per Road Type

3) Where the actual AADF rates for any road are significantly different for each direction and Table NG1.1 indicates different road types in each direction, the highest traffic category shall be applied in both directions.

4) Where one-way traffic systems and/or other traffic management schemes result in multi-lane traffic, standard growth rate predictions and lane correction procedures may result in an inaccurate road classification overall. In such cases, whenever reasonably practical, the flow of commercial vehicles should be monitored separately, and traffic calculations completed, for each traffic lane in question.

5) Where an existing road is near, or beyond, its working life, and is expected to be re-constructed within the foreseeable future, a temporary re-classification of the road will usually be appropriate, pending its re-construction. Such temporary re-classifications should be undertaken by agreement. Similarly, where roads are expected to be re-constructed within the guarantee period of the reinstatement, it will usually be appropriate to amend methods, materials or performance requirements for those reinstatements, by agreement.

6) The national network of roads carrying, up to 125 msa within a 20 year period, and classified as Types 0 to 4 roads according to the requirements of this Specification, will yield a distribution similar to that shown in Table NG1.2.

Table NG1.2 - Estimated road Classification

7) It is expected that the roads in any Authority area will show a distribution similar to that shown in Table NG1.2, although there will be some local variations. In future years, there may be cases where traffic flows change, to such a degree, that re-classification will be necessary. It is expected that re-classification to a lower category will frequently occur, as well as re-classification to a higher category.

NG1.4 - NG1.5 There are no Notes for Guidance

NG1.6 Alternative Options

1) New Materials

Research into new or improved reinstatement materials is often undertaken by various organisations and such work may produce materials that perform as well as, or better, than those specified in this Specification. In order to allow such materials to be proven, by development testing, the materials and relevant layer thicknesses quoted in this Specification may be amended or supplemented, subject to prior agreement.

2) Local Materials

Materials may be available locally that have not been defined in any national Specification, but which, by experience, are known to give acceptable performance in service. In order to allow the use of such proven local materials, the materials and relevant layer thicknesses quoted in this Specification may be amended or supplemented, subject to prior agreement.

3) Alternative Compaction Equipment

Alternative compaction equipment, including any compaction devices not specifically permitted within Section S10 and Appendix A8, may be permitted, provided it has been proven to be capable of achieving the same degree of compaction as any other option permitted in Appendix A8.

a) For all compaction plant not shown in Appendix A8, an approved operating procedure shall be established, by development testing, in an appropriate trench environment with the relevant material option, to prove equivalence with the compaction requirements of Appendix A8. The development testing shall be verified by an independent, accredited laboratory.

b) Where alternative compaction plant is intended to be used on more than one type of material, as defined in Appendix A8, an approved compaction procedure shall be established, as defined in section NG1.6 3) a) above, for each intended category of material.

NG1.7 Immediate Works

The minimum thickness of bituminous surfacing material, required by Section S1.7.1 for the reinstatement of all immediate works, is 40 mm. A greater thickness may be required, in areas subject to frequent or heavy traffic, if further remedial works, during the 10 days permitted duration of immediate works, are to be avoided.

NG1.8 Apparatus within the Road Structure

1) Some apparatus may already be present at shallow depth, within many existing road structures and special requirements may apply to their reinstatement. Both the Undertaker and the Authority are likely to have particular criteria and this Specification may be altered, or supplemented, subject to prior agreement, to accommodate any such requirements.

2) Not all new apparatus will need to be installed to the full depth or width expected by this Specification; an example is small diameter cabling and/or ducting for telecommunications, traffic controls, etc. This Specification may be altered, or supplemented, subject to prior agreement, to accommodate these applications.

NG1.9 - NG1.11 There are no Notes for Guidance

« Previous | Contents | Next »