Traffic light system

Categorisation system

Each test result is checked against the specification and classified into a category with limits relating to that specification. This enables the 'engineer' to quickly assess a particular sample.

How to use the categorisation system

When reports are received, a look through the category classification or colour coded boxes on the report will quickly highlight which reports need extra attention.

Category A, green


Generally if the material falls into the A category or green box then the material is within specification for those tests undertaken on the material delivered and provided it is laid correctly, should present no problem.

Category B, amber


Materials falling into the B category or amber box can again be considered satisfactory and which in practice will give no significant difference in performance between it and a category A material as they are marginally out of specification and generally fall within the limits of repeatability. The client will need to undertake testing to demonstrate this.

Category C, red


Materials which fall into the C category or red box require extra attention as the test result indicates that there may be something wrong with the material. The sample of material may be far enough outside the specification limits so that the performance of the material may be adversely affected. Not all results which fall into this category can be regarded as unacceptable.

Each result has to be examined in the area where it is out of specification and in its intended use with a judgment made by the client in conjunction with the approved laboratory or other nominated consultant, to discuss if any further action needs to be taken or whether remedial action is required. Discussions between the client or supplier, highway authority, recycle group and nominated laboratory are recommended at this stage. It is the responsibility of the material supplier to immediately address and investigate any failures and take action to prevent re-occurrence. They should advise the recycling group of their findings and action taken.


  1. Materials which fall into the C category should be discussed with the testing laboratory, the Sustainability and Innovations Group and any nominated Sustainability and Innovations Group consultant to determine the appropriate action necessary. The supplier must update Sustainability and Innovations Group members immediately by email alert, along with Sustainability and Innovations Group web pages.

  2. If materials have been placed within the highway, the supplier or utility is responsible for any monitoring or investigatory work and provide details to the relevant highways authority.

  3. Result reporting: UKAS laboratory test data to be sent to the Sustainability and Innovations Group via by the last Friday of every month.

  4. Plant protection safety concerns: the binder added to the material (SMR, HBM and TMF) should be such that the strength of the product does not exceed the maximum permitted strength requirement of the SROH

    The final strength of the material should be such that re-excavation can be undertaken using suitable hand tools to confirm the position of buried underground services. This is a requirement of the Health and Safety Executive, laid down in their publication HSG 47 – Avoiding Danger from Underground Services.

  5. The material supplier must give authorisation to the nominated Laboratory to pass on all test results to the Sustainability and Innovations Group and other interested parties. This will be carried out by email on a monthly basis.

    UKAS Lab test results confidentiality requirement: All suppliers shall give permission for their results to be publicised openly on the Sustainability and Innovations Group web pages.

  6. All category C (red) failures must be addressed immediately.

  7. Non-compliances identified within the category C (red) classification need to be addressed immediately. A warning will be issued by email to all partner organisations (including utility employer and highway authorities) by the supplier identifying the failure. They will contact the Sustainability and Innovations Group to ensure the concerns are addressed and rectified. Suppliers should also provide details of corrective actions implemented and inform all Sustainability and Innovations Group members.

  8. Surfacing materials must not be reinstated until the recycled material has attained sufficient strength or has an immediate bearing index sufficient to allow adequate compaction of overlaying materials and sustain adequate traffic loading.

    Overlaying of the HBM is permitted at any time for HBM with IBI category IPI25. Alternatively, overlay is only permitted once the material has gained sufficient strength to enable compaction of the overlying layer.

  9. Typically, when utility waste arisings are sent to a third party recycling facility, in order to be fully recovered and cease to be classified as a waste, the WRAP Quality Protocol for the Production of Recycled Aggregates from inert waste is to be adhered to. The quality protocol sets out end of waste criteria for the production and use of aggregates from inert waste.

    If the criteria are met, the aggregates will normally be regarded as having been fully recovered and to have ceased to be waste.

    A quality protocol identifies the point at which waste, having been fully recovered, may be regarded as a non-waste product that can be used in specified markets, without the need for waste management controls. Quality protocols have been produced for a range of materials.

    For the avoidance of doubt, clays and soils are not considered to be aggregates for the purposes of the quality protocol.

Sustainability and Innovations Group

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