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Understanding BSI PAS128 Surveys

At Groundwise, we specialise in BSI PAS128 Type D Surveys – 
but what is PAS128?

What is a PAS128 Survey?

BSI PAS 128 provides a robust methodology for delivering utility surveys in the UK. It focuses on levels of accuracy – referred to as Survey Category Types – that you can specify when requiring a PAS 128 compliant underground utility survey.

Survey Types?

There are four Survey Category Types, ranging from D – A:

PAS 128 Survey Type D

Desktop Utility Record Search. A thorough desktop search of all statutory asset owners to supply their record data. Sometimes referred to as a C2 Search.

Groundwise specialises in PAS128 Survey Type D – we have provided our Desktop Utility Search service since 2000!

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PAS 128 Survey Type C

Underground utility plotted from utility record data only, but with site reconnaissance to match utility record with physical utility street furniture as a best fit.

Groundwise does not undertake Survey Type C.

PAS 128 Survey Type B

An on-site utility mapping survey 
using multiple geophysical 
instruments. The output from this survey shall be each linear 5 metre section of utility depicted as a Quality Level (QL) 1-4 for horizontal and vertical detection accuracy.

Groundwise does not undertake Survey Type B.

PAS 128 Survey Type A

Utility verified and positioned by 
physical identification. This may be by strategically positioned vacuum 
excavation, hand dug trail pitting or by visual inspection within a utility chamber.

Groundwise does not undertake Survey Type A.

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+ What is PAS 128 - Underground Utility Detection about?

Sponsored by the Institute of Civil Engineers, this standard provides a way to accurately map underground utility networks.

+ Who is PAS 128 - Underground Utility Detection for?

BSI PAS 128 on underground utility detection can be used by:

  • Practitioners such as surveyors, geophysicists, and subsurface utility engineers
  • Clients such as engineers, constructors, project managers and utility owners who are responsible for recording information about underground utilities

+ What does PAS 128 - Underground Utility Detection cover?

PAS 128 on underground utility detection specifies requirements for the detection, verification and location of existing and new underground utilities including active, abandoned, redundant or unknown underground utilities and the location of their associated surface features (e.g., manhole covers and utility markers).

It applies regardless of where these utilities are located (e.g., in urban or rural areas, in the street, or on private sites such as hospitals or airfields).

BSI PAS 128 also sets out the accuracy to which the data are captured, the quality expected of these data and a means by which to assess and indicate the confidence that can be placed in such data. Specifically, it covers:

  • Project planning and the scoping process
  • The classification system for quality levels based on survey type, location accuracy, inclusion of post-processing and level of supporting data
  • Desktop utility records search
  • Detection
  • Verification
  • Location
  • Deliverables

+ Why should you use PAS 128 - Underground Utility Detection?

BSI PAS 128 on underground utility detection has many benefits. These include:

  • This PAS can lead to more effective planning and safer execution of street works, civil works, ground works and utility-based activities
  • It provides clarity about the service provided and methods employed; a consistent approach to data capture; and accountability for the work undertaken
  • It can be used to indicate the presence or absence of underground utilities before conducting further ground investigation prior to breaking ground
  • It can be used to support the detection, location, and avoidance of buried services as part of a permit to break ground safe system of work
  • It enables better informed decisions using more complete, up-to-date, and accurate data, helping ensure the safety and timely progress of site development
  • It can help prevent or reduce conflicts, delays, unnecessary work, damage to third party assets, utility service disruptions, redesigns, personal injuries and even loss of life
  • It can supply data that could lead to unrealized benefits, such as the use of remote robotic techniques that reduce the need for intrusive maintenance
  • It can help improve asset modelling capabilities
  • It can help manage risk, improve efficiency, and develop users’ expertise

Click here to read more about PAS128 2022: Specification for 
Underground Utility Detection, Verification and Location