What is PAS128?

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 category types

There are four Survey Category Types ranging from D - A:

  • PAS 128 Survey Category Type D

    Underground utility plotted from utility record data only (not detected by geophysical methods).

  • PAS 128 Survey Category 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.

  • PAS 128 Survey Category Type B

    Utility detected by multiple geophysical methods to obtain a horizontal position and/or vertical position. (Depth) For the positional accuracy of each QL-B sub category please refer to the Accuracy Diagram.

  • PAS 128 Survey Category 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.

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