TfL (TRANSPORT FOR LONDON) CASE STUDY
Structures OPI Detailed Examinations
PROJECT NAME: AR & OPIs Great Eastern Line, East London Line and West Anglia Line
AREA: London and South East
SERVICES: Population of Asset Register and completion of detailed OPIs
CLIENT: TfL – Transport for London
In May 2019 we started working as a sub-contractor to Pole Star for an asset register (AR) and operational property inspection (OPI) project on the Great Eastern Line on behalf of RFLi.
At the same time we also started working as a sub-contractor to Cleashar Contract Services (CCS) for an AR and OPI project on the East London Line and West Anglia line.
Both contracts with an end client of TfL. Our work for CCS also included a number of shaft inspections, some minor enabling works and repairs as well as the inspection of lineside buildings. Both contracts mentioned above are still on-going at the time of writing.
The contracts required us to start collecting an asset database from scratch, upon which detailed OPIs were conducted. Careful liaisons with the access authorities for each line was required and reconnaissance visits were undertaken, and a programme of works planned.
Teams of STE5 inspectors were deployed using the Building Asset Management System (BAMs) developed by Pole Star (supplied by TfL). BAMs is a structured asset management system that enables assets to be recoded with spatial information and attribute data compiled for each. Handheld tablets were used out in the field with live links to the data base making the collection and upload of site data very streamlined. The AR’s were built in line with NR/L3/CIV/006 handbook 11 OPAS specification, meaning the data was structured in a Site-Block-Location-Asset hierarchy ready for detailed OPIs to be conducted.
Once the ARs were completed the stations were revisited for detailed OPIs. This entailed STE5 inspectors collecting data as per NR/L3/CIV/006 handbooks 7A & 7B. ARs were checked and condition and defect information recorded as per the standard.
An element of the works for CCS required us to obtain track access and the use of MEWPs to conduct the OPIs.
Liaison with CCS planners enabled us to find the most efficient use of weekend closures on the line and the organisation of the use of MEWPs. We planned and executed the possession work using our inhouse teams comprising safety critical staff, machine controllers, POS and STE5 inspectors.
Upon completion of the site data collection, our inhouse STE2 conducted reviews of the data, writing recommendations and signing off reports for issue. We also worked with Pole Star to help develop a pdf report output from the database to meet client requirements.
A total of 11 stations were visited for RFLi and 32 stations for London Overground.
Throughout the projects listed above we have explored the use of advance technology to help give added innovation and enhancements to safety, quality and cost of the works. As part of the LO project we were asked to look at structure G271 utilising only our Unmanned Aerial Vehicles (UAVs). Structure G271 forms part of Rotherhithe Station on the East London Line at Ch 6700 between Wapping and Canada Water.
Structure G271 was last examined late April 2017 where personnel were restricted to capturing images of the structure from platform level.
Areas that could not be seen and accessed by personnel were readily reached by our UAV. Elements of the structure that have never been seen before have now been imaged and these images can be used to expand upon previous inspections.
We deployed the DJI Phantom 4 Pro (P4P) quadcopter type drone fitted with a custom built collision-resistant cage and two “bolt-on” light sources.
A two-person flight crew was utilised for the inspection, comprising pilot and structures examiner.
The examiner directed the pilot using a hand-held monitor receiving the video feed from the UAVs camera and gave instructions to the pilot, i.e. direction and distance to fly.
The examiner then captured an image of a defect or area of interest.
The UAV flights were undertaken in accordance with our Permission for Commercial Operations, the Operations Manual and the UAV Aerial Survey Work Package Plan.
A total of 388 images were captured during the inspection flights.
We utilise the practice of directed flight in which the pilot is given instructions, on where to manoeuvre the UAV and what to capture images of, by the examining engineer.
This entails the engineer observing the camera feed directly and giving precise manoeuvring instructions to the pilot, i.e. move in a particular direction for a certain distance, capture an image etc.
In this instance the engineer is also a qualified UAV pilot, and familiar with the handling characteristics of the P4P and is able to set the camera parameters and capture the images thereby allowing the pilot to concentrate entirely on the flying task, reducing pilot workload, which results in a significant increase in safe operating and productivity.
The application of UAV to visually inspect structures in difficult to access spaces has proven to be practicable in terms of both safety and efficiency when compared to traditional access methods such as MEWP and roped access.
Elements of the structure that were previously unseen have been successfully imaged with numerous defects identified at various locations throughout the tunnel.