Appendix A - OC information

South West Unit

A defect register, listing 28 schemes, was submitted by the SW representative. The list contained information on the sites and some of the defects that had been recorded between 2015 and 2019. Fourteen of the scheme identifiers were coded ‘0300’ signifying that the work was carried out as part of routine maintenance. The other 14 schemes were coded ‘0100’ which means they were part of a structural maintenance programme. A decision was made to concentrate on the latter sites as these schemes require to be designed and were likely to provide more relevant information to the study. Some images of the early life failures are shown in Figure A-1.

Figure A-1 - Images of early life failures in the SW, as described in text above
Figure A-1 - Images of early life failures in the SW

The OC highlighted some general recurring themes associated with the early life defects:

  • defects can appear within weeks of surfacing;
  • defects were mostly localised and didn’t appear to be ‘traditional’ surface defects;
  • all defects were in areas which only received a surface course replacement; and
  • there were no indications of structural failure in the lower layers prior to surfacing.

Table A-1 shows the name of the structural maintenance scheme submitted, date completed, and if additional information was provided. The schemes were also cross-referenced with data held on IRIS and the last column shows the recorded number of defects for the scheme. 

Table A-1 - SW schemes with early life defects
Scheme name Date laid Other Information (OC) No. of recorded defects (IRIS)
A77 Sandyford to St Quivox 01/03/2015 - Total 18: potholes (13) & fretting (5).
M8 Jct 31 EB 17/05/2015 - Total 13: potholes (10) & fretting (3).
M74 Blackwood NB 22/06/2015 Potholes, material type, images Total 139: potholes (119); fretting (12); pumping (5); cracking (2); & joint (1).
A77 Minishant 11/10/2015 Material type Total 110: potholes (81); heaving (10); depression (10); various (5); & chip loss (4).
A77 South of Ardwell Farm 07/11/2015 Crazing Total 57: potholes (35); fretting (19) & heaving (3).
A77 Drumellan Farm 04/05/2017 Pavement failure report Total 93: potholes (85): fretting (5) & heaving (3).
M80 Jct 2 NB 21/06/2017 Material type Total 18: potholes (18).
M80 Jct 2 SB 16/09/2017 Material type Total 7: potholes (4): fretting (2) & open joint (1).
A77 Ballantrae 06/12/2018 Displacement & cracking, material type, laying data/conditions Total 6: fretting (5) & heaving (1).
A737 Roebank to B777 07/08/2019 Displacement & cracking, material type, laying data/conditions Total 2: potholes (2).
A77 Dalquat to Minnybae 26/10/2019 Pothole with cracking, material type, laying data/conditions Total 3: potholes (3)
A77 Whattriggs to Inchgottrick (SB) 05/08/2019 Pothole with cracking, material type, laying data/conditions Total 13: potholes (6); fretting (6) & rutting (1).
A75 Halfway House May 2019 - Total 2: crazing (2)
A75 Muirfad July 2019 Potholes, material type (*defect reported August 2020) *No IRIS data found

The SW schemes above represent 25% of the structural maintenance schemes on IRIS that recorded Cat 1 and Cat 2 defects between 2015 and 2019.

South East Unit

A defect register, listing 5 schemes, was submitted by the SE unit representative. The schemes are listed in Table A-2. All the schemes were part of a structural maintenance programme and coded ‘0100’. An image of an early life failure for one of the schemes is shown in Figure A-2.

Table A-2 - SE schemes with early life defects
Scheme name Date laid Other Information (OC) No. of recorded defects (IRIS)
A720 Lothianburn to Dreghorn (WB) 03/09/2015 Potholes in wheel track Total 27: potholes (13); fretted areas (5); cracking (6): & open joints (3).
A1 Brockholes 23/04/2018 Investigation report Total 15: Potholes (8), some recorded as multiple; cracking/difference in level (5); & trenching (2).
A1 Wallyford to Dolphinston (SB) Nov 2018 Two potholes or depressions with cracking, images Total 6: potholes (5) & open joint (1).
A702 Bigger High Street May 2019 Single pothole, image Total 2: potholes (2).
A1 Gladsmuir to Bankton (NB) Aug 2019 Single pothole, image No IRIS data found

The SE schemes above represent 10% of the structural maintenance schemes on IRIS that have recorded Cat 1 and Cat 2 defects between 2015 and 2019.

Figure A-2 - Early life defect in the SE, as described in text above
Figure A-2 - Early life defect in the SE

North East Unit

Only one scheme was identified by the NE unit and the information is summarised in Table A-3. The OC highlighted that they had been experiencing some early life joint failures but these had been rectified by the laying contractor once identified.

Table A-3 - NE schemes with early life defects
Scheme name Date laid Other Information (OC) No. of recorded defects (IRIS)
A9 Blackford (NB) April 2017 Initially appeared as rutting, core report. Total 8: Depression (3); potholes (2); fretting (2) & failed repair (1).

The NE scheme above represents 3% of the structural maintenance schemes on IRIS that have recorded Cat 1 and Cat 2 defects between 2015 and 2019. An image of the early life failure for the Blackford scheme is shown in Figure A-3.

Figure A-3 - Early life defect in the NE, as described in text above
Figure A-3 - Early life defect in the NE

North West Unit

No information was submitted by the North West Unit. According to IRIS, 56 schemes recorded Cat 1 and Cat 2 defects between 2015 and 2019.