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PAS 128; are you getting the best use of your budget?

Updated: Jan 31

The PAS 128 specification for underground utility detection provides a robust methodology for delivering utility surveys in the UK.

Introduced in 2014, it focuses on the levels of accuracy that you can specify when commissioning a PAS 128 compliant underground utility survey. But how does it differ from other survey options and more importantly; is it the best use of your budget?

PAS 128

What is PAS 128?

PAS 128:2014 is the latest specification for underground utility detection. It differs from other survey options  The purpose of the PAS 128 specification is to set out the accuracy to which survey data is captured. As well as this, the quality expected from the data and the confidence that can be placed in the data will be included. Although, it is not relevant for all utility surveys. Where it is appropriate to specify a PAS 128 survey, there will be benefits for the client, the practitioner and the general public.

The specification covers:

  • The project planning and scoping process.

  • The classification system for quality levels based on the survey category type, the location accuracy, the need for post-processing and the level of supporting data.

  • Desktop utility records search.

  • Detection.

  • Verification.

  • Location.

  • Deliverables.

PAS 128 provides a strong procedure for delivering utility surveys in the UK. There are four Survey Category Types. These are referred to in the specification and each one focuses on levels of precision specified in an underground utility survey that is PAS 128 compliant.

Why was PAS 128 needed?

  • It aimed to combat the inconsistent costs and service levels across the utility survey industry.

  • To highlight inferior data being provided by inexperienced surveyors.

Inaccurate data on the existence and location of utility assets can be detrimental to a projects smooth running. A lack of reliable information during the design and construction phases can result in expensive errors. The safety of workers and the public can be put at risk as well as many other needless problems.

As a result, it is vital that accurate information for the location of underground utilities is available. Accurate mapping of utility networks helps to improve asset modelling capabilities with more resolute outcomes.

The benefits of PAS 128 ensure a high level of accuracy and certainty of the results for each utility detection survey. This increased accuracy and reliability provided to the client enables them to plan effectively for all utility-based activities.

Survey quality types

We can help answer the question 'are you getting the best use of your budget'. We want to demystify a complex technical area and improve communication between clients and practitioners; it is important to understand the hierarchal approach PAS 128 has to the production of utility surveys. There are four survey quality levels which the client can specify: A through to D.

It is written for practitioners to adhere to, with clients specifying the survey they require. Your survey provider should help you in determining the most appropriate intensity with which it is carried out.

4 quality levels of PAS 128

Above: The 4 quality levels of PAS 128 and their relative cost.

PAS 128 Quality Levels of information

Above: PAS 128 Quality Levels of information.

Two technical directors at The SUMO Group were appointed to the Drafting Panel and the Steering Group by ICE and BSI to assist with the writing of the PAS 128 specification. This was also part funded by SUMO. The guiding role that SUMO played in the creation process, means that we have an in-depth understanding of how PAS 128 works.  Also, the best and most economical approach to applying PAS 128 certified survey options to your site and budgetary needs.

At SUMO we understand that many client’s commissioning a survey are obligated by ‘higher powers’ to specify a PAS 128 compliant survey. However, the relevance of methodologies can be easily misunderstood. We are often (mistakenly, in our opinion) asked for the highest, most costly quality level of PAS 128 survey to be completed throughout a site. It is a common misconception that by asking for the highest-level survey, you will receive the best survey. In fact, in most cases this isn't actually the best approach. Asking for the highest quality level of PAS 128 may be too intensive for your specific site area. But this could also needlessly raise your survey costs.

The PAS 128 specification was written to allow for the survey area to be subdivided so that various and appropriate levels of PAS 128 survey can be applied to different areas. Referencing the quality level tables above means that we can satisfy a projects' needs whilst also addressing safety and financial requirements with varying quality levels and relative costs. For example:

“I need an M4P PAS 128 survey; because it’s the best”

Yes, it is the most intensive PAS 128 survey option. However, it may not be the best solution for your specific site.

“Tell me why”

Your site is predominantly open greenfield, partly tarmac carpark and may not require the intensive survey grid used in an M4P survey. Conducting an M4P survey throughout this specific site will also take longer to survey and will cost considerably more. In this case, an M1P survey for the greenfield space and an M2P survey for the carpark may be the best solution. It will still be fully PAS 128 compliant and it will also be considerably cheaper than a full M4P survey!

PAS 128 grid

So, to answer our question – Are you currently getting the best use of your budget when commissioning a PAS 128 survey or could we help you to do so, whilst saving money?

PAS 128 is setting the standards within the survey industry. Survey providers offering PAS 128 compliancy must adhere to these specifications and standards. Having said this, you know that with PAS 128 you're getting the most assured standard of survey for your money. The comparison of quotes should also be much easier, as all compliant quotes should be based on a similar methodology.

Having a brief understanding of PAS 128 whilst commissioning your survey will ensure the best chance of maximising your budget. Any quality survey provider which offers PAS 128 compliancy such as SUMO will be able to discuss, agree and scope the survey with you.

Unfortunately, in our view, PAS 128 does not provide enough client guidance on commissioning a survey. However, clients have a defined role in the PAS 128 survey process.

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