What is PAS 128?

 

BSI PAS 128 (Publicly available specification 128)

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As the demand on the nation’s infrastructure continues to grow due to new developments, and the need to replace and/or maintain existing utilities increases, it is essential to have accurate information on the existence and location of underground utilities.

PAS 128 was introduced by the Institution of Civil Engineers (ICE) in 2014 to set out the requirements and best practices to be followed to provide support to the client when requesting and analysing a specific survey type. The standard was developed in order to improve the clarity and consistency in underground utility detection.

PAS 128 aims to give a better understanding as to what accuracy an underground utility has been located to and what survey techniques have been used. This is achieved by classifying surveyed utilities with quality levels. These are detailed below:

 

QL-A

Verification

The Utility has been observed/is visible. This can be achieved with the lifting of manholes/inspection chambers or if utilities have been exposed during excavation or trial holes. Other methods to achieve this quality level are possible using gyroscopic mapping.

 

QL-B

Detection Using EML or GPR

This is when the utility has been located using geophysical techniques. Either by EML (CAT scan), GPR (Ground penetrating radar) or a combination of the two. Accuracy is increased if both methods successfully locate the utility.

 

QL-C

Site reconnaissance

Validation of existing record information during a site visit. This can be demonstrated by visual reference to street furniture. Topographical features or evidence of previous street works i.e. Reinstatement scars.

 

QL-D

Desktop utility record search

The collation of all existing utility records only. Desktop drawings only provided with an unknown accuracy. A prerequisite for a survey type b but can be carried out as a separate service.

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