History advanced at London Waterloo
London Waterloo is the UK’s largest and busiest railway station, covering an area of nearly 100,000m2 and handling over 95 million passengers a year. It is the main terminus for services to the south coast and southwest of England and connects directly to London’s busiest tube station.
Last year Laing O’Rourke was selected to create an object-based three-dimensional digital model of the entire station complex using state-of-the art laser scanning and digital modelling techniques. It was a unique project for the business – and one that would ordinarily be carried out by a traditional engineering consultancy.
The commission recognised our unrivalled combination of in-house digital engineering expertise, collaborative working practices and delivery-focused approach, ensuring that the model would be fit for the widest range of future purposes.
Laing O’Rourke has produced a comprehensive digital model capturing extensive and complicated information. It is expected to unlock efficiencies in asset management.David BarnesNetwork Rail Project Manager
In the past 10 years, passenger numbers at Waterloo have risen by 50 per cent. With a further 30 per cent increase expected by 2030, the Network Rail / South West Trains Alliance embarked on a five-year £1.2 billion capacity upgrade programme in 2014.
The work will include lengthening existing platforms from eight-car to 10-car capacity and reopening the former international platforms. The scheme is also likely to require station alterations to provide adequate pedestrian access and enhance the passenger experience.
The initial problem facing the project team, however, was that information on the station’s design and construction was spread over 10,000 record drawings in a variety of formats, many of which were incomplete. Network Rail also wished to align itself with the UK Government’s strategy to use collaborative three-dimensional Building Information Modelling (BIM) on all of its projects by 2016.
In May 2013 Network Rail commissioned Laing O’Rourke to create the first ever complete, object-based three-dimensional digital model of London Waterloo station. Finalised in October 2013, the outputs of the project were:
– A three-dimensional object-based model of the existing station to an agreed level of detail in Industry Foundation Classes (IFC) and native file format using the following hierarchy of information: laser scan data, DWG record drawings, PDF and other record drawings.
– A range of three-dimensional model outputs including a selection of two-dimensional plans and sections.
– Laser scan data from selected zones in the form of both the native point cloud and TruView files.
– Support to Network Rail in identifying the value digital engineering can bring to the Waterloo station redevelopment and help to communicate that to their wider teams.
David Barnes, Network Rail’s project manager, said: "Laing O’Rourke has produced a comprehensive digital model of London Waterloo – the UK’s busiest railway station. This has required the use of the latest surveying techniques and advanced modelling skills to digitally capture extensive and complicated information. The model will be used to underpin a wide range of future developments and is expected to unlock efficiencies in project and asset management".
The contract required Laing O’Rourke to use a mix of existing drawings and new laser scanning data to create a model of the entire asset including the main platforms and concourse, the former international terminal, the adjacent Waterloo East station, the underground tunnels beneath the station and the external facades.
Around 60 per cent of the station was surveyed using laser scanning technology with the remainder based on a combination of record drawings and measurement checks.
Laing O’Rourke’s specialist survey team – part of its Select Plant business – used a Leica Geosystems ScanStation P20 high-definition three-dimensional laser scanner, one of the most advanced quantity surveying instruments available.
Capable of measuring and recording up to a million points per second and storing the accumulated data through its 256GB on-board hard drive, the unit is able to generate three-dimensional profiles of structures in a fraction of the time required using traditional equipment. At a typical operating distance of 40m, the surface points are only around 5mm apart and recorded in RGB colours with an accuracy of 2mm.
"This is definitely the future of surveying," says Select’s specialist survey product lead, Liz Saunders. "The Leica P20 is considered to be the best three-dimensional laser surveying scanner around, and has already been used on several Group projects with innovative new applications. Its combination of high speed and accuracy, extensive optical range, easy interface and ruggedness means that it can be quick to set up and deliver results faster and more efficiently than ever before."
"In a few weeks at Waterloo we were able to record a highly detailed survey that would be almost impossible with traditional instruments," said Frik Du Preez, one of our senior land surveyors. "The P20 is quick and, in the rail environment, the ability to fit around operational constraints was a huge advantage. Many elements of the station, such as the roof, were inaccessible without causing major disruption. While others, like the tunnelled walkways, would normally present highly technical challenges. We were able to record all the details – the edges, the curves and every imperfection."
Building the model
Once the scanning was complete, the biggest challenge was converting the masses of point data – the ‘point cloud’ – into usable three-dimensional object information.
Traditionally, the point data would have been used to generate a mesh representation of a facility. But Laing O’Rourke took it a step further, adapting the data to create objects that can be embedded with data. The model was built by a team of highly skilled digital engineers using a combination of Autodesk Revit 2014 and Graphisoft’s ArchiCAD software, and each was responsible for a specific zone. Once the zone models were complete, they were integrated into a single federated model using Navisworks Manage 2014.
"The Waterloo project was a huge undertaking for all involved, requiring us to push current technology to its limits," recalls Antony Aucote, one of our senior construction process engineers. "The point clouds produced by the surveying team were initially so large that none of our standard modelling software could cope with them.
"Overall zoning and detailed splitting of the clouds was agreed to reduce the files to a manageable size. Each cloud then was converted into an Autodesk Revit 2014 model usable format by utilising the ReCap package. Once converted, each cloud could be linked into Revit and assembled to recreate each major area of the station. Then, once assembled, the cloud could be viewed in both two- and three-dimensional plans and sections, and the modelling process could begin.
"Each major element of the station was created from scratch in Revit to ensure all key details were accurate – its height, width, length, major reveals and extrusions, and overall material type – a process which required the point cloud to be sectioned up many times over to ensure the accuracy of the model. Once created, each model element was then placed and checked in plan and section to ensure that it fell within the agreed level of tolerance against the point cloud data. With hundreds of columns and roof trusses forming just a part of the platform area, it was a very involved and meticulous task.
"At regular intervals throughout the project, photographs were taken of the more congested or detailed areas to enhance understanding. Historical drawings were also referenced. Key members of the team visited the site to gain first-hand knowledge of the station to support the interpretation of the point clouds correctly. They also employed their extensive experience of construction methodologies to ensure that everything modelled was structurally correct and that no key interfaces had been missed.
"The variety of challenges experienced on the project highlighted perfectly the team’s capabilities. They were expert modellers, with the engineering experience to interpret and collate complex information from multiple sources simultaneously, and all while maintaining absolute accuracy, meeting very tight sectional deadlines and yet still endeavouring to deliver beyond the client’s expectations."
To correspond with its intended use, elements in the Waterloo model were developed to be within 50mm of any deviations in the point cloud. Where this level of tolerance could not be directly achieved, objects were divided into smaller elements to meet the required standard. The same level of tolerance applied to modelled elements developed from PDF or scanned record drawings, due to the inability to ‘snap’ to points from these information sources and the effect of scale on line weights. Where the model was developed from DWG record drawings, a tight modelling tolerance of 15mm to the drawing was achieved.
Although the object-based model that Laing O’Rourke delivered may prove suitable for multiple applications, it was developed primarily for Network Rail to use as the basis for early-stage design works and cost planning of the proposed Waterloo station redevelopment. It is anticipated that the native laser scans files, which Laing O’Rourke also supplied, will be used by Network Rail, as the project progresses into detailed design, to test the geometric fit of any proposed solutions.
The model is detailed enough to incorporate individual elements such as columns, beams and parts of track – each of which is embedded with data relating to materials, finish and dimensions.
The collaboration between Network Rail and Laing O’Rourke was a key element of the project. The team adopted the working practices recommended through BS 1192:2007. These included:
– The development of a common data environment (CDE) for sharing, communicating and validating project data. ProjectWise was used for this purpose.
– Agreed zones within the project for spatial coordination and to ensure coordinated modelling of all elements.
– Coordinated ‘light’ model formats used for overall synchronisation, clash detection and to remove barriers to entry for employer / client to digital engineering data – e.g. Navisworks Freedom.
– Regular meetings to ensure compliance with the digital engineering execution plan and the project workscope documents.
As part of the collaboration process, a series of digital engineering engagement sessions were undertaken on the project. These workshops were open to all interested stakeholders within Network Rail and at the station.
For the first time Network Rail now has a complete digital model of Waterloo station, which it can use as a basis for asset management and future development. It also has the data in a wide range of formats to ensure maximum flexibility.
Laing O’Rourke is also now well-placed to provide further support to Network Rail on Waterloo and other major infrastructure assets. The project builds on the company’s already considerable experience in this field, which includes modelling the as-built foundations at the Leadenhall Building in the City of London, monitoring diaphragm wall movements at London Gateway Port and modelling existing assets at Manchester Town Hall.
While the technology is moving forward at pace, the business is committed to remaining at the forefront of its application. With more powerful, more sophisticated tools making their way to market, the creation of an object-based three-dimensional digital asset model within the blink of a Google Glass eye may be sooner than we think.
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