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 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.
PAS 128 – Survey Category Type B
Utility detected by geophysical methods (single or multiple) 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 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 D
Underground utility plotted from utility record data only (not detected by geophysical methods).