The Scottish Government

« Previous | Contents | Next »

Listen

SPECIFICATION FOR THE REINSTATEMENT OF OPENINGS IN ROADS

S2 Performance Requirements

S2.1 General

S2.1.1 The performance requirements of this Specification shall apply to roads which are maintainable or prospectively maintainable at public expense. In all other cases, the performance should match that of the existing construction, as far as reasonably practicable.

S2.1.2 Performance requirements shall apply to the immediate, interim and permanent reinstatements of Undertakers' excavations. If the surface profile of a reinstatement exceeds any intervention limit during any guarantee period, remedial action shall be carried out to return the surface profile of the reinstatement to the as-laid condition defined in Section S2.2.1.

S2.1.3 No new guarantee period shall be required unless the cumulative settlement intervention limit is exceeded and an engineering investigation has been completed in accordance with Section S2.5. Requirements for the re-excavation and subsequent reinstatement, as determined from the results of the engineering investigation, shall be agreed and completed in accordance with Section S2.5.

S2.1.4 Reinstatement of Modular Surface Layers is described in Appendix A12. For all modular surfaces the effective width of a reinstatement shall be as follows:

1) For modular surfaces consisting of modules up to and including 300mm (or the nearest imperial equivalent), the effective width (W) of a reinstatement shall be the distance between two parallel lines drawn 150mm outside the edges of the excavation (see Fig S2.1A).

Figure S2.1A - Effective Width of Reinstatement - Modules £ 300 mm

2) For modular surfaces where one side of the module is greater than 300mm (see Fig S2.1B), the effective width of a reinstatement (W) shall be the distance between the outer extremities of any modules that overlap the edges of the excavation.

3) Where there is evidence of further adjoining modules being affected by the excavation, the effective width shall be extended to include such modules.

Figure S2.1B - Effective Width of Reinstatement - Modules > 300 mm

S2.1.5 Surface deformation resulting from vehicles over-running reinstatements within paved footways, including footpaths and cycletracks, shall be excluded from all measurements carried out for the purposes of monitoring the reinstatement surface performance, unless such reinstatements have been carried out under the provisions of Section S8.4.

However, properly constructed paved footways and their reinstatements may both be reasonably expected to withstand occasional over-run by non-commercial vehicles (less than 1.5 tonnes unladen). Where it can be shown that occasional over-run by non-commercial vehicles has caused surface deformation to a reinstatement within a paved footway and the adjacent surfaces do not show any associated surface deformation, the Authority may notify the Undertaker accordingly, whereupon the Undertaker shall restore the reinstatement to the as-laid profile.

S2.2 Surface Profile

S2.2.1 As-laid Profile

1) The reinstatement of any surface shall be completed so that it is as flat and flush as possible with the surrounding adjacent surfaces. There should be no noticeable depression or crowning in the surface. Construction tolerances at the edges shall not exceed 6mm.

2) Once the reinstatement is registered as completed and opened to traffic, the Intervention Limits specified in Sections S 2.2.2 to S 2.2.5 shall apply.

3) At the end of the guarantee period, where the profile of the existing surfaces adjacent to the reinstatement is uniform and the surface of the reinstatement is outside the intervention limits, the Undertaker shall carry out remedial works to restore the surface profile of the reinstatement to a condition consistent with the adjacent surfaces.

4) It should be recognised that the surface profile of reinstatements carried out in restricted areas (for example, around surface boxes and fixed features) using hand tools may be difficult to match with adjacent machine-laid surface profiles. In these cases, localised variations in the hand laid surface profile should be acceptable to the Authority provided that they are within the specified tolerances.

S2.2.2 Edge Depression - Intervention

1) An edge depression is a vertical step or trip at the interface of the reinstatement and the existing surface.

2) Intervention shall be required where the depth of any edge depression exceeds 10 mm over a continuous length of more that 100 mm in any direction; see Figure S2.2.

Figure S2.2 - Edge Depression Limits

S2.2.3 Surface Depression - Intervention

1) A surface depression is a depressed area within the reinstatement having generally smooth edges and gently sloping sides, forming a shallow dish; see Figure S2.3.

2) Intervention shall be required where the depth of any area of surface depression spanning more than 100 mm in any plan dimension exceeds the intervention limit X shown in Table S2.1

Figure S2.3 - Surface Depression Limits

Table S2.1 - Intervention Limits - Surface Depression

3) Earlier intervention shall be required if the depression alone results in standing water wider than 500 mm or exceeding one square metre in area, at 2 hours after the cessation of rainfall.

S2.2.4 Surface Crowning - Intervention

1) Surface crowning is where the reinstatement is above the mean level of the existing adjacent surfaces; see Figure S2.4.

2) Intervention shall be required where the height of any area of surface crowning spanning more than 100 mm in any plan dimension exceeds the intervention limit Z shown in Table S2.2.

Figure S2.4 - Surface Crowning Limits

Table S2.2 - Intervention Limits - Surface Crowning

3) Earlier intervention shall be required if crowning alone results in standing water wider than 500 mm or exceeding one square metre in area, at 2 hours after the cessation of rainfall.

S2.2.5 Combined Defect - Intervention

1) A combined defect is an area within the reinstatement where any combination of edge depression, surface depression and/or surface crowning, overlap.

2) Where combined defects occur, the intervention limits for surface depression and surface crowning, shown in Section S2.2 and Tables S2.1 and Table S2.2 as intervention limits X and Z respectively, shall be reduced by 20% and rounded up to the nearest whole number, subject to a minimum of 10 mm.

3) Intervention shall be required where the extent of any individual defect, spanning more that 100 mm in any plan dimension, exceeds the combined defect intervention limit for the relevant defect, as defined in Section S2.2.2 2), Table S2.1 and Table S2.2. The individual defects shall be measured, and the 20% reduction in intervention limits applied, as shown in Section NG2.2.5.

S2.2.6 Condition at End of Guarantee Period

1) At the end of the guarantee period the condition of the reinstatement shall not be required to be superior, in any respect, to either the condition existing at the time of excavation or to the condition of the adjacent surfaces.

2) Where the profile of the existing surfaces adjacent to the reinstatement is uniform and substantially superior to the surface of the reinstatement, the Undertaker shall carry out remedial work to restore the surface profile of the reinstatement to a condition consistent with the adjacent surfaces.

S2.3 Fixed Features

S2.3.1 As-Laid Profile

All fixed features, such as edgings, channel blocks, drainage fixtures, surface boxes and ironware etc., should be as level and flush as possible with the adjacent surfaces and shall be installed to meet the following level criteria:

1) Fixed features shall be laid to coincide with the mean level of immediately adjacent surfaces.

2) The construction tolerance between the levels of the fixed feature and immediately adjacent surfaces shall not exceed +/- 6mm.

3) Drainage features shall be set flush with the adjacent surface and subject to a construction tolerance of not more than 6mm below the level of the adjacent surface.

S2.3.2 Intervention

1) Intervention is required where the mean level of edgings, channel blocks, surface boxes and ironware etc., does not coincide with the mean level of the immediately adjacent surfaces, within a tolerance of 10 mm.

2) In the case of drainage fixtures, intervention is required where the mean level does not coincide with the mean level of the immediately adjacent surfaces, within a tolerance of +6 mm to -15 mm.

S2.4 Surface Regularity

S2.4.1 Requirements

At any time during the guarantee period, the longitudinal regularity in the direction of traffic flow at the surface of the permanent reinstatement in the road and the adjacent surfaces shall comply with the following requirements:

1) The number of surface irregularities along a permanent reinstatement should not exceed the lower limit shown in Table S2.3.

Table S2.3 - Surface Regularity

2) Where the number of surface irregularities along a permanent reinstatement exceeds the lower limit shown in Table S2.3, the number of irregularities along the adjacent road shall be recorded, in the direction of traffic flow, for comparison.

3) Where, the number of surface irregularities along a permanent reinstatement and the adjacent road both exceed the lower limit shown in Table S2.3, the number of irregularities recorded along the reinstatement should not exceed the product of the number measured along the adjacent road and the multiplier shown in Table S2.3.

S2.4.2 Measurement

1) Surface irregularities may be measured using the TRL rolling straightedge. However, the rolling straightedge shall not be used to determine surface regularity where:

a) The line of a trench is parallel to the centreline of the road for less than 30 metres length.
or b) The line of a trench is parallel to the line of traffic flow for less than 30 metres length.
or c) The line of a road and/or the trench follows a bend with a radius of less than 500 metres.
or d) The number of surface irregularities recorded along the adjacent road exceeds the upper limit shown in Table S2.3.

2) Where the rolling straight edge cannot be used, the surface regularity shall be assessed by an other agreed method.

S2.4.3 Monitoring

For the purposes of monitoring the surface regularity of road reinstatements, relevant lengths of the trench should be divided into test sections of 30 metres length. The upper and lower limit values for surface irregularities, for each 30 metre section length, are shown in Table S2.3. For the final section length, which may exceed 30 metres but will be less than 60 metres, the limits should be calculated pro rata, and rounded up to the nearest whole number.

S2.5 Structural Integrity

The requirements for structural integrity are applicable to both paved and unpaved surfaces.

S2.5.1 Cumulative Settlement

1) The cumulative settlement of any reinstatement is the perpendicular distance, from the level of the adjacent surfaces, to the original surface of the reinstatement; see Figure S2.5. This measurement will effectively include the thickness of any additional materials added during any preceding remedial work.

Figure S2.5 - Cumulative Settlement

2) If the cumulative settlement of a reinstatement exceeds the limits shown in Table S2.4 at any time within the guarantee period, an agreed engineering investigation shall be carried out, jointly with the Authority. The investigation should establish whether settlement is likely to continue and determine the extent of remedial action required.

Table S2.4 - Structural Integrity

3) Where it is necessary to re-excavate a reinstatement to carry out an engineering investigation, the subsequent permanent reinstatement shall be deemed to be new and the guarantee period shall begin again.

4) Where very deep excavation work is carried out in bad ground, consideration should be given to an agreed extension of the interim reinstatement period. An appropriate extension will allow the reinstatement and surrounding ground to achieve an acceptable degree of stability before permanent reinstatement is required. The performance requirements of Section S2 shall apply throughout the extended interim period.

S2.5.2 Bad Ground

Bad ground is deemed to be natural or made-up ground between the base of the excavation and the binder course level, which contains any of the following:

a) Class E Unacceptable Materials, as specified in Appendix A1.
b) Materials that are loose or friable in their natural state and are not self-supporting at an exposed face.
c) An excessive amount of rocks or boulders, loose random rubble, penning, setts or cobbles etc, at any depth where their removal during excavation could cause loosening of the ground adjacent to the excavation.
d) Materials that are saturated, regardless of whether free or running water is present.

S2.6 Skid Resistance

S2.6.1 General

The texture depth, Polished Stone Value (PSV) and Aggregate Abrasion Value (AAV) at the running surface of all interim and permanent reinstatements in all roads shall comply with the following requirements:

1) There is no requirement to provide a texture depth, PSV or AAV that is superior to that existing at the running surfaces adjacent to the reinstatement.

2) For rigid roads, where the surface of the concrete road slab is the running surface of the road and has been randomly grooved, a brushed surface finish to the requirements of Table S2.5 shall be permitted for small excavations, narrow trenches and other openings less than 1 metre wide.

S2.6.2 Texture Depth

1) Subject to the requirements of Section S2.6.1, for all bituminous surface course materials permitted in Appendix A2 and for rigid roads where the surface of the concrete road slab is the running surface of the road, the texture depth shall comply with the requirements of Table S2.5.

Table S2.5 - Texture Depth (Sand Patch Method)

2) Texture depth shall be measured in accordance with BS 598: Part 105: Sand Patch Method. The current BS 598 sand patch test may not be suitable. For narrow reinstatements, a modified version of the BS 598 sand patch test, using 25 ml of sand, may be used.

3) Texture depth can be calculated from a sand patch diameter in mm using the following formula:

The approximate patch diameters for the required texture depths are shown in Table S2.6.

Table S2.6 - Sand Patch Method - Equivalent Patch Diameter

4) For the purposes of monitoring texture depth, the entire reinstatement shall be divided into notional units of 18 square metres and a minimum of three texture depth measurements shall be taken on each notional unit. Comparison tests on the existing road should be carried out adjacent to the reinstatement, as close to the reinstatement edge as practicable.

5) Where the TRL Mini Texture Meter may be used by agreement, it shall be used in accordance with BS598: Part 105.

S2.6.3 Polished Stone Value (PSV)

1) For the purposes of determining PSV requirements, reinstatements in roads are classified into two site categories, according to the apparent degree of risk associated with the site location, as follows:

a) Site A - Potentially High Risk
Traffic signals, pedestrian crossings, railway level crossings - including 50 m approaches
Roundabouts and their exits - including 50 m approaches
Bends < 100 m radius where the speed limit > 40 mph (65 kph) - including 50 m approaches
Downhill gradients > 10% for more than 50 m (single or dual carriageway)
Uphill gradients > 10% for more than 50 m (single carriageway only)

or b) Site B - Average or Low Risk
All other situations on single and dual carriageways, including the following:
Generally straight sections of carriageway
Approaches to and across major/minor road junctions
Bends of 100 m radius or greater, at any speed limit
Downhill/Uphill sections of 10% gradient or less

2) Subject to the requirements of S 2.6.1, for all bituminous surface course materials permitted in Appendix A2, the PSV of all precoated chippings and the coarse aggregate in all mixes used without precoated chippings at the running surface shall comply with the requirements of Table S 2.7. The coarse aggregate in all mixes used with precoated chippings at the running surface shall have a minimum PSV of 45.

Table S2.7 - Bituminous Roads - Polished Stone Value

3) The PSV shall be tested in accordance with SHW Clause 915.3

4) Where an interim surface course contains an aggregate that may not comply with the requirements of Table S2.7, a surface treatment may become necessary before the reinstatement is made permanent. In this event, the requirements of Table S2.7 are applicable only to the coarse aggregate contained within the surface treatment and not to the underlying aggregate within the interim surface course.

5) Where a high friction coating is to be applied to a reinstatement to match an existing coating, an alternative PSV may be specified by agreement, in place of the requirements of Table S2.7, depending upon the nature of the site and the period over which the friction coating will be absent.

6) Where the Authority has evidence that a different PSV has proved satisfactory, an alternative PSV may be specified by agreement in place of the requirements of Table S2.7, depending upon the nature of the site.

7) Where a permanent surface course contains more than one type of aggregate or aggregates from more than one source, all coarse aggregates within the mixture shall comply with the PSV requirements of Table S2.7

S2.6.4 Aggregate Abrasion Value (AAV)

1) Subject to the requirements of Section S2.6.1, for all bituminous surface course materials permitted in Appendix A2, the AAV of all precoated chippings and the coarse aggregate in all mixes used without precoated chippings at the running surface shall comply with the requirements of Table S2.7.

Table S2.8 - Bituminous Roads - Aggregate Abrasion Value

2) The AAV shall be measured in accordance with BS 812: Part 113.

3) Where an interim surface course material contains an aggregate that may not comply with the requirements of Table S2.8, a surface treatment may become necessary before the reinstatement is made permanent. In this event, the requirements of Table S2.8 are applicable only to the coarse aggregate contained within the surface treatment and not to the underlying aggregate within the interim surface course.

S2.7 Sampling and Testing

S2.7.1 All sampling and testing shall be carried out by a laboratory holding current UKAS accreditation covering the specified method of testing, unless otherwise agreed.

« Previous | Contents | Next »