Utility Surveys

Chiswick High Street

Mobile Ground Probing Radar (MGPR) combined with Pas128 along a section of the A205 Chiswick High Street
3D AutoCAD MGPR & Pas128 results to be added to 3D topographical base drawing also produced by SVS Ltd

SVS Ltd were tasked with providing a variety of surveying solutions in order to gather the appropriate level of detail from the High Street site enabling initial design concepts and investigation works to be undertaken.

The site consisted of a single lane running south west to north east, dual return lanes running north east to south west, a cycle lane all of which are running over two railway bridges, a public house and the entrance into Kew underground station. To add further complication, the site also ran through a bus and red route.

In order for the MGPR and Pas128 findings to be accurately recorded the initial task for SVS Ltd was to establish site control. This would enable all data being collated by multiple teams to be accurately tied into one another.

First to mobilise to site was our land survey team who began to log detail from within the site parameters and surrounding topography.

It was agreed, at an earlier site “recce” that the MGPR unit could also be deployed during day light hours. This would be deployed utilising #2 survey vehicles running with the traffic and without a traffic management scheme that would have certainly caused disruption and some stress to road users.

The advantages of employing the stream up in these environments is its ability to flow with the traffic simply by applying some common sense precautionary measures in order to protect the device, the survey vehicles and of course our operatives.

The MGPR coverage of the site was monitored in real time, utilising the “track map” facility eradicating the possibility of any data gaps. This data would be post processed back to HQ and cross referenced against both QL D and the Pas128 QL B findings.

The site recce also established that a different approach would be required for the more robust Pas128 QL B survey to undertaken along the adjoining footpaths and cycle lanes.

“SVS Ltd were able to provide a comprehensive solution to a variety of tasks for initial site investigation works, early design concepts and the supplementary works that took place to establish visual detail of the tram tracks & sleepers and the conditions of the bridge protective membrane beneath – all in all not a bad day’s work”

Simon Bailey FCInstCES
Managing Director
Full Pas128 QL B Survey

As good as ground probing radar / MGPR devices are it must be acknowledged that a true Pas128 utility detection and mapping exercise is achieved through deploying multiple devices and lifting / location techniques, the results from which enable the operative to provide a more informed confidence rating of the services and subsurface features they have been able to locate

You can see even from the initial findings drawing, that the Pas128 exercise undertaken along the adjoining footpaths has certainly provided a wealth of additional knowledge of the site, the volume and type of the buried utility services and a number of services that will require precautionary measures at a time when actual construction works take place

A recent innovation has been the introduction of “Caution” triangles to our drawings. These are an obviously visual aid that instantly draws attention to a particular point of interest or an item the attending surveyor believes would be worth highlighting for future planning

One particular and quite interesting feature that was identified at regular intervals and depths running along the front of Kew underground station was a series of tram line sleepers

These features, still very much intact were simply buried in situ when the tram infrastructure was removed in around 1910

Surprisingly, we also found what has been determined to be the tram lines as well. Not sure if such a valuable resource would be left in the ground today

In all the various exercises undertaken have drawn an incredible amount of good, tangible data from what is an involved and complicated site