FOI reference: FOI/18/00345
Date received: 6 February 2018
Date responded: 6 March 2018
With regard to the Sand Patch test results provided by Breedon, answers appreciated to the following questions (which I have numbered consecutively from my previous submission) also under a FOI/ Environmental Information (Scotland) Regulations 2004 (EIRs) request:
12. As 60% of the Determination of Texture Depth tests were not carried out due to the weather (Rain), how was the road assessed as being safe to be driven on?
13. As the Sand Patch method requires the surface being measured to be dry, please advise the following:
How could the Sand Patch test not taken Northbound (Ref 7033/A) due to Rain be taken on the same section of road Southbound (Ref 7032/A) on the same day of 8 Sep 2017?
How could the Sand Patch tests not taken Southbound (Ref 7037/C & 7037/D) due to Rain be taken on the same section of the road Northbound (Ref 7036/C & 7036/D) on the same day of 12 Sep 2017?
How could the Sand Patch test not taken Northbound (Ref 7038/A) due to Rain be taken on the same section of the road Southbound (Ref 7039/A) on the same day of 13 Sep 2017?
14. I note that the texture depth readings, where recorded, range from 1.1mm to 1.3mm. What is the minimum and/or maximum texture depth tolerance allowable?
15. If the readings had been found to be out with this allowable range, what would be the resulting response?
16. Is there a drawing available which identifies the sections of road against the chainage used to reference the Sand Patch data results?
17. Which side of the road is Northbound and Southbound?
18. Should the Location Reference be noted as Eastbound or Westbound for this section of road instead?
19. What checks were carried out to ensure that there was no conflict of interest between the company carrying out the surfacing work and the one carrying out the texture depth analysis?
20. Was any independent analysis carried out to check the results provided?
As the information you have requested is 'environmental information' for the purposes of the Environmental Information (Scotland) Regulations 2004 (EIRs), we are required to deal with your request under those Regulations. We are applying the exemption at section 39(2) of the Freedom of Information (Scotland) Act 2002 (FOISA), so that we do not also have to deal with your request under FOISA.
This exemption is subject to the 'public interest test'. Therefore, taking account of all the circumstances of this case, we have considered if the public interest in disclosing the information outweighs the public interest in applying the exemption. We have found that, on balance, the public interest lies in favour of upholding the exemption, because there is no public interest in dealing with the same request under two different regimes. This is essentially a technical point and has no material effect on the outcome of your request
Response to your request
I have numbered our response for ease of reference.
12. Specified quality control techniques applied at asphalt production plants, and during laying, are aimed at providing a consistent product that continually meets the specification requirements. The texture testing is undertaken as a check on site to confirm that compliance has been achieved and failures are rare. In this case,given that 100% of the completed testing was in compliance with the specification, combined with historical knowledge of the product, this was considered to be a representative sample.
13. If rain does not persist throughout the day there may be opportunities to undertake localised testing in dry conditions before trafficking.
14. As per Annex B of Interim Advice Note 154/12, Revision of the Specification of Highway Works Vol 1, Series 900, Clause 921 states that for a thin surface course system to cl942 with a 10mm aggregate size (as used at this site) an average per 1000m section must be no less than 1.1mm and no more than 1.6mm, furthermore the average for a set of 10 individual measurements must not be less than 0.9mm.
15. Such failures are rare but this would be assessed on a site by site basis following investigation and consideration by the supplier, the designer and the client, as appropriate, to determine whether any remedial actions are required. Measures can sometimes be taken to increase low texture, or the material can be removed and replaced.
16. Please refer to Annex A of this request.
17. Southbound is travelling toward the A87 Bun Loyne Junction,northbound is travelling toward the A82 Invermoriston Junction.
18. There is no set protocol for naming direction of travel on a particular route but it is usual chosen based on the general direction of the whole route rather than on individual sections. In this case the A887 runs generally southwest to northeast and it is designated as northbound and southbound for simplicity.
19. Texture depth testing required by the 4G operating company contracts must be undertaken by a laboratory holding accreditation granted in respect of such sampling and testing:
(i) by the United Kingdom Accreditation Service (UKAS), or (ii)by the European co-operation for Accreditation of Laboratories (EAL).
20. There was no independent analysis carried out to check the results.
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