The PAS 128 utility survey specification is the current industry standard for all underground utility surveying needs. It was brought about by a coalition of a range of organisations including; British Standards Institution (BSI), Institution of Civil Engineers (ICE) as well as several Companies ranging from engineering entities, utility surveying companies and large consultant firms. The reason was to bring more clarity, quality and all-round understanding to a subject that many outside of the industry understand fully.

With the specification the aim was to allow the utility surveying industry to maintain a constant quality. To allow potential clients a standard to hold against the company providing the service. 

The PAS 128 utility survey specification was published in June 2014. 

At the beginning of 2012, the stakeholders in the utility survey industry got together at BSi in London to discuss utility surveying in the UK and whether or not it needed regulating. Here it was agreed that whilst acknowledging the good work of The Survey Association in producing ‘The Essential Guide to Utility Survey’, there was indeed a need for an industry-wide consensual document. 

In particular, specifying the minimum requirements needed in carrying out a utility survey. The resulting specification has been written for practitioners to adhere to, with clients specifying the quality level of the survey they require.

There are a few reasons why this standard was needed. Firstly the service providers needed an industry standard and clients required a specification to allow sensible procurement decisions to be made.

The main focus which bridges the gap between provider and client is the fact that a standard specification is available to all. This allows clients to compare like for like quotes for survey works and provides a degree of accountability that was previously absent from the industry.

There are a wide range of professions that would benefit from the use of the specification:

Utility Survey Companies 

Consultants 

Project Managers

Site Managers 

Engineers 

Spade Operators 

Surveyors 

Geophysicists

And anyone who is dealing with the underground mapping information or ground penetrating radar information. 

There are a range of survey types and methods contained within the PAS 128 utility survey specification.

Desktop utility records search is the identification of underground utilities via the collation and analysis of existing utility records. A survey provider will take all the existing information from all the asset owners in the area and consolidate the information on to a base map and issue via DWG and PDF forms.

Once the desktop utility record search has been completed and the information has been placed on the base map, the site team can then do a walkthrough of the site confirming the desktop search information. They can collect thorough information on inspection chambers, marker posts and any above surface features to enhance the deliverables available through a Type D survey.

A detection survey is an accurate way of determining the locations of buried services in a location. Using the latest surveying techniques and cutting edge technologies a survey company can be successful in locating services, obstructions, buried anomalies and more. The outputs are each given a location accuracy and quality level which is outlined within the PAS 128 utility survey specification. This provides the client with valuable information in the location and accuracy of the service. 

The most accurate survey type goes one step further than an underground utility survey. This survey type allows the survey company to 100% confirm the location, type and nature of the service by exposing it and recording its metadata via hand dug trial holes, vacuum excavation or visual inspection inside an inspection chamber using confined spaces entry procedures.

The quality levels for a PAS 128 utility survey are as follows::

QL-D – A service recorded in a desktop search

QL-C – A service which has been identified during a site reconnaissance and can be enhanced from the QL-D level.

QL-B4 – A utility segment which is suspected to exist but has not been detected and is therefore shown as an assumed route.

If any of the following QL-B PAS128 designations are appended with a P (i.e. QL-B2P), this indicates that post-processing of GPR data was used.

QL-B3 – Horizontal location only of the utility detected by one of the geophysical techniques used.

QL-B2 – Horizontal and vertical location of the utility detected by one of the geophysical techniques used. 

QL-B1 – Horizontal and vertical location of the utility detected by multiple geophysical techniques used.

QL-A – A service that has been verified with trial holes and visually inspected.

Conclusion

The PAS 128 utility survey specification has been a great addition to the utility locating industry. It has brought about a higher understanding of the information clients are receiving and provided survey companies with a benchmark standard to work with. In turn, this has allowed a fair comparison between service providers and brought a higher level of training and professionalism to the industry.