S2 Performance Requirements
S2 Performance Requirements
S2.1.1 The performance requirements of this Specification shall apply to Roads that 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.
1) For all interim reinstatements, the main consideration as to meeting the performance requirements generally set out in Section S2 is primarily one of maintaining road safety. This is particularly important where Deferred Set Mixtures (DSMs) are used in roads, especially the higher road categories.
2) 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 an 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 where all sides of the module are 300mm or less (or the nearest imperial equivalent), the effective width of a reinstatement (W) shall be the distance between two parallel lines drawn 150mm outside the edges of the excavation (see Fig S2.1A).
2) For modular surfaces where one side of the module is greater than 300mm, the effective width of a reinstatement (W) shall be the distance between the outer extremities of any modules that overlap the edge of the excavation (see Fig S2.1B).
3) Where there is evidence of further adjoining modules being affected by the excavation, the effective width shall be extended to include such modules.
S2.1.5 Surface deformation resulting from vehicles over-running reinstatements within paved footways, footpaths and cycle tracks, 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.
S2.1.6 However, properly constructed paved footways and their reinstatements may both be reasonably expected to withstand occasional overrun 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, footpaths or cycle tracks 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.
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 significant depression or crowning in the surface. Construction tolerances at the edges of the reinstatement shall not exceed +6mm/-3mm.
2) Once the reinstatement is completed to either interim or permanent and opened to traffic, the Intervention Limits specified in Sections S 2.2.2 to S 2.2.5 shall apply.
3) 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 or a trip at the junction between ironwork and reinstatement.
2) Intervention shall be required where the depth of any edge depression exceeds 10 mm over a continuous length of more than 100 mm in any direction; see Figure S2.2.
S2.2.3 Surface Depression / Crowning - 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.
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 depth of any area of surface depression or the height of any area of surface crowning spanning more than 100 mm in any plan dimension exceeds the intervention limit X or Z shown in Table S2.1.
|Reinstatement Width W
|Intervention Limit X or Z
|Up to 400||10||10|
|Over 400 to 500||12||10|
|Over 500 to 600||14||12|
|Over 600 to 700||17||14|
|Over 700 to 800||19||16|
|Over 800 to 900||22||18|
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 Combined Defect - Intervention
1) A combined defect is an area within the reinstatement where any combination of edge depression, surface depression or surface crowning overlap exists.
2) Where combined defects occur, the intervention limits for surface depression and surface crowning, shown in Section S2.2 and Table S2.1 as intervention limits X and Z, 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 than 100 mm in any plan dimension, exceeds the combined defect intervention limit for the relevant defect, as defined in, Table S2.1. The individual defects shall be measured, and the 20% reduction in intervention limits applied, as shown in Section NG2.2.5.
4) 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
S2.2.5 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 the condition of the adjacent surfaces.
2) 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.
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 (excluding drainage features) 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.
4) At a pedestrian crossing point that is flush with the adjacent surfaces, the kerbs shall be relaid flush with the adjacent surfaces to a tolerance of 0 to +6mm.
Figure S2.5 illustrates the relationship between immediately adjacent surfaces and the surround reinstatement to newly constructed Undertaker's Apparatus when setting the level of access covers and frames to the Apparatus.
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 0 mm to -10 mm.
3) In the case of a pedestrian crossing point, intervention is required where the depth of any edge depression at the interface between the paving (which can include tactile units) and the dropped kerb exceeds 6mm over a continuous length of more than 100mm in any direction.
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 wheel track shall comply with the following requirements:
1) The number of longitudinal surface irregularities along a permanent reinstatement should not exceed the lower limit shown in Table S2.3.
|Surface Irregularities not less than (mm)||Irregularities per section|
|Lower Limit||Multiplier||Upper Limit|
2) Where the number of longitudinal surface irregularities along a permanent reinstatement exceeds the lower limit shown in Table S2.3, the number of irregularities along the adjacent wheel track shall be recorded, in the same 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 longitudinal surface 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.
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 250 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 another agreed method.
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.
The requirements for settlement 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 S2.6. This measurement will effectively include the thickness of any additional materials added during any preceding remedial work.
2) If the cumulative settlement of a reinstatement exceeds the limits shown in Table S2.4 at any time within the guarantee period, the Undertaker may elect to carry out suitable remedial action. Where the Undertaker does not elect to carry out remedial action, an agreed engineering investigation may be carried out by the Road Authority in accordance with the provisions of Section 131 of the 1991 Act. The Undertaker shall be afforded the opportunity to be present at the investigation and it should establish whether the Undertaker has complied with their duties with respect to reinstatement.
If default under their duties is established:
a) The Undertaker will bear the cost of the investigation and carry out the required remedial action, and
b) A new Guarantee Period will also be afforded to the Road Authority as a consequence for the affected area of reinstatement.
|Reinstatement Width (mm)||Intervention Limit Q|
|Bad Ground Conditions (S2.5.2)||All Other Ground Conditions|
|Up to 1000||2.5% U ) whichever||1.5% U ) whichever|
|or 30 mm ) is greater||or 30 mm ) is greater|
|Over 1000||2.5% U ) whichever||1.5% U ) whichever|
|or 35 mm ) is greater||or 35 mm ) is greater|
3) Where it is necessary to re-excavate a reinstatement to carry out an engineering investigation and it is found to be defective under the conditions of S2.5, 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.
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 requirement:
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.
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.
2) The average depth of carriageway surface macrotexture shall be measured using a volumetric patch technique described in SHW Clause 921 for bituminous surfacing and Clause 1026 for concrete surfacing. For concrete or narrow reinstatements a modified version using 50% of the test medium (e.g. sand or glass beads) may be used.
3) For the purposes of monitoring texture depth, the entire reinstatement shall be divided into notional units of 18 square metres and tested at evenly spaced intervals as follows:
- Reinstatement of small excavations - single measurement centred within the reinstatement
- Reinstatement of >2m2 to 18m2 - 3 measurements
- Reinstatement >18m2 - 3 measurements per 18m2
- Trenches 300mm wide or less - as above but centred along the centreline of the trench
Figure S2.7 illustrates the requirements of Section S2.6.2 (3) apart from small excavations.
4) Where the test patch extends beyond the edge of the reinstatement the test shall be repeated using half the volume of test medium. Any comparison tests on the existing road should be carried out adjacent to the test locations in the reinstatement, as close to the reinstatement edge as practicable.
5) The TRL mini texture meter may be used by agreement.
1) Unless specifically and reasonably required by the road authority, all aggregates used in surface courses will have a PSV value of not less than 55.
2) Where specifically required by the Road Authority, to simplify the determination of the PSV requirements for aggregates in asphalt surface courses, 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)
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
3) For all bituminous surface course materials permitted in Appendix A2, the PSV of all pre-coated chippings and the coarse aggregate in all mixes used without pre-coated chippings at the running surface shall comply with the requirements of Table S2.7. The coarse aggregate in all mixes used with pre-coated chippings at the running surface shall have a minimum PSV of 45. The PSV shall be tested in accordance with BS EN 1097-8.
|Road Type||Reinstatement Minimum PSV|
|Site A Potentially High Risk||Site B Average or Low Risk|
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 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) For all bituminous surface course materials permitted in Appendix A2, the AAV of all pre-coated chippings and the coarse aggregate in all mixes used without pre-coated chippings at the running surface shall comply with the requirements of Table S2.8.
|Road Type||Reinstatement Maximum AAV|
|All Pre-coated Chippings||SMA, Material to PD6691 Surface Courses|
(See also Section S6.4 for permitted surface course options)
2) The AAV shall be measured in accordance with BS EN 1097-8
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.
4) The past use of Table S2.8 has indicated that the minimum values noted are appropriate in most cases. However, where an Authority has alternative requirements for aggregate properties then this information shall be supplied to the Undertaker. Where this is the case the Undertaker shall specify aggregate properties in accordance with this information subject to Section S2.6.1 (1).
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.
S2.7.2 The Road Authority may carry out sampling and testing at its discretion. If there is no agreement between the Road Authority and Undertaker on the test results and findings, further testing may be undertaken by a UKAS accredited laboratory to reconcile the matter.