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PAS 128: It's Cost-Effective If You Do It Smart

Updated: Jan 31

For many of SUMO’s clients, it is an internal requirement for most projects, that they obtain a PAS 128 compliant survey.

In practice, there are many ways of achieving this, but we often hear that “PAS 128 compliancy comes at a cost”. So we got together with SUMO’s industry leading professionals to discuss PAS 128 and concluded that it’s easy to be cost-effective, if you do it smart! Keep reading to find out more…

PAS 128 survey

So, what is PAS 128?

PAS 128:2014 is the latest specification for underground utility detection. The purpose of the PAS 128 specification is to set out the accuracy to which survey data is captured. The quality expected from the data and the confidence in the data is highlighted. 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.

As a result, PAS 128 provides a strong procedure for delivering quality utility surveys in the UK. There are four Survey Category Types They 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.

PAS 128 Survey

Why was PAS 128 needed?

  • To combat the inconsistent costs and service levels prevalent 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 phase can also result in expensive errors. At the same time, the safety of workers and the public can be put at risk, as well as many other needless problems.

It is vital that accurate information for the location of underground utilities is available. Accurate mapping of utility networks also 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 of information provided to the client, then enables them to plan effectively for all utility-based activities.

So, how do I keep costs low whilst obtaining sufficient survey data?

The specification is actually written for practitioners to adhere to. Clients then specify the survey type and quality level they need. Your survey provider should help you to determine the most appropriate survey intensity.

It all starts with understanding the hierarchical 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.

PAS 128 data

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 original PAS 128: 2014 specification. The guiding role that SUMO played in the creation process; means that we have an in-depth understanding of how PAS 128 works. This means that SUMO can also identify the best and most economical approach to applying PAS 128 certified survey options to your site and budgetary needs.

PAS 128 survey

At SUMO we understand that many client’s commissioning a survey are obligated by ‘higher powers’ to specify a PAS 128 compliant survey. But, the relevance of methodologies can be easily misunderstood. We are often (mistakenly, in our opinion) asked for the highest and 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 and could also needlessly raise your survey costs.

The key point to recognise, is that the PAS 128 specification was written to allow for the survey area to be subdivided. This is 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.

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

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

“Tell me why”

Your site is predominantly open greenfield and only partly tarmac car park. So, this may not require the intensive survey grid used in an M4P survey across the entire site. 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, plus it will also be considerably cheaper than a full M4P survey!

Varying Levels of PAS 128

Above: Example of varying Levels of PAS 128 being applied to a site area. Notice how the most intensive PAS 128 levels have been concentrated in areas where typically lots of utilities are found; such as around the buildings. A less intensive PAS 128 quality level has been applied to the field areas. In doing this, you can still obtain sufficient survey data at a fraction of the cost.

In summary…

PAS 128 is setting the standards within the survey industry. Survey providers offering PAS 128 compliancy must adhere to these specifications and standards. As a consequence, you can be certain that with PAS 128 you're getting the most assured standard of survey for your money. The comparison of different supplier quotes should also be much easier. This is because all compliant quotes should be based on a comparable methodology.

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

Unfortunately however, in our view, PAS 128 does not provide enough client guidance in practice, on commissioning a survey. Especially as clients have a defined role in the PAS 128 survey process. A review of the existing PAS is about to get underway (which SUMO will be involved with) and will focus on adding extra informative sections to improve guidance to clients and to achieve better clarity.

In the meantime, SUMO has put together an easy to understand Client Introduction to PAS 128: 2014. This should start you off in the right direction!

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