How RATS accelerated drainage rehabilitation scheme selection for the M25 motorway

AtkinsAtkins has over 20 years’ experience in the planning, scoping and data review of CCTV surveys through to the development, management and site supervision of rehabilitation schemes. During this time, we have worked with several UK water companies, airport owners and highways operators understanding their problems and developing appropriate solutions, some of which have involved the development IT systems / digital tools to manage the CCTV and sewer rehabilitation process.

CCTV surveys of sewers and drains are costly and disruptive activities generating large datasets which require time consuming, manual review to determine the improvements required. Subjective decisions can lead to inconsistency and repetitive decision-making has the potential for human error. In these days of needing to do more for less, the ability to quickly and accurately extract value from CCTV surveys has never been greater. Recognising the opportunity to generate up-front efficiencies in scheme development Atkins has now largely automated the rehabilitation scheme selection process with its digital tool RATS (Rehabilitation Automation Tool for Sewers / Stormwater).

RATS automatically reviews CCTV survey data (.XML files or similar), coded in accordance with the Manual of Sewer Condition Classification (MSCC) (or Pipeline Assessment Certification Program (PACP)), and recommends appropriate rehabilitation schemes based on critical modes of structural failure. It is built up from a series of logic statements which have been compiled into a decision tree and programmed for automation. This determines whether a pipe requires isolated repairs or manhole to manhole remediation. For a complex combination of defects or visual reviews of specific defects (eg holes), the surveys are selected for Engineer Review.

Following a successful trial, Atkins was subsequently appointed by ConnectAtkins Plus Services (CPS) in late 2019 to review the CCTV survey data associated with over 600km of highway drainage on the M25. Connect Plus Services (CPS) is a consortium of Balfour Beatty, Atkins and Egis Road Operation UK, which has a 30-year DBFO (Design Build Finance Operate) contract with Connect Plus to undertake servicing on behalf of Highways England. CPS is responsible for the operation and maintenance of the M25 motorway and adjoining roads (motorways and all-purpose trunk roads. The purpose of the review was to better understand the structural condition of the highway drainage, to allow rehabilitation to be proposed for the worst defects and investment plans developed. The main drivers for the work were:

·         Exfiltration from pipes that could cause subsidence.

·         Flooding on the carriageway as a result of pipe failure.

·         Defective pipes located adjacent to geotechnical features.

Initially RATS was configured to process HADDMS (Highways Agency Drainage Data Management System) CCTV data and export full length reline, patch repair and excavation rehabilitation proposals, together with recommendations for intruding connections and root removal and infiltration prevention. Checking and verification of the output was carried out through the interrogation of over 200,000 lines of defect coding to identify specific defects, various spellings of technical terms (eg collapse) and duplicate, overlapping or repeat surveys. As part of the Engineer Review a QA check on the quality of the CCTV coding was undertaken to feedback to CPS and its sub-contractors.

Of the 602k of CCTV survey data, 88% had no significant structural defects. For the remaining 12% various schemes were developed which were prioritised against defect severity, operational severity, pipe diameter, strategic location, proximity to geotechnical features, accident / collision data and flooding severity. In addition, a full assessment of operational problems was undertaken to understand where planned maintenance is needed. This looked at trends in data to help identify cause / effect relationships to enable better network management.

AtkinsRATS was chosen to undertake the work to allow a programme of improvements to be generated for investment planning. The data was processed, schemes developed, and a report prepared in just four months at less than 50% of the cost to undertake the work manually. With all results generated in GIS, the output was linked to other datasets such as land use, traffic flows, lane usage and topography to further refine the output and prioritise improvements for implementation during planned lane closures to avoid reactive work.

Quintin Viljoen, Professional Head Linear, Connect Plus Services commented, “Having trialled this tool we have implemented it over a much larger scope. We were able to demonstrate that we could automate elements of our drainage design process, for example the pipe network’s structural and surface defects, prioritise assets as well as recommend potential renewal treatments.

The recommendations made by RATS concurred well with our own engineering recommendations. The use of this tool now provides notable design efficiencies. We will continue to calibrate this tool for our network to enhance its capabilities as this has become an indispensable part of our drainage review, analysis and prioritisation of works.”.

As demonstrated, RATS can easily be configured to suit different coding standards or client requirements to quickly interrogate all CCTV data to maximise the value generated for maintenance and operational activities. For further information, please contact andy.taylor@atkinsglobal.com  or the UKSTT Young Professional of 2019, jason.moran@atkinsglobal.com,  or visit our website at https://rehabilitationautomationtoolforsewers.com/

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