Digitising Euston

London Euston station is the sixth busiest railway station in the UK and acts as the southern terminus of the West Coast Main line, the busiest intercity passenger route in Britain and the main gateway to the capital from the North West and West Midlands.

Located in a complex area, Euston station is connected to the London Underground network and is within short walking distance of Kings Cross and St Pancras stations. Euston has also been named as the preferred southern terminus of the proposed HS2 line to Birmingham and the North of England.

The site for Euston station was chosen by George and Robert Stephenson in the early 1830s. Designed by Philip Hardwick and built by William Cubitt, the station first opened in July 1837. Originally the station consisted of two platforms accessed via the “Euston Arch”. As the population and surrounding infrastructure grew, the station was expanded in stages to include 15 platforms by the 1890s.

In 1962, the original building was demolished and the Euston station that we now know was developed and opened in 1968, following the electrification of the WCML and ushering in the “electric age”.

Planning ahead

Moves are now afoot to again redevelop Euston station and the surrounding rail infrastructure, with a view to providing much needed capacity and further enhancing the links between London and the North of England. As a precursor to the enabling works, Bridgeway Consulting was asked to act as principal contractor for all survey works on behalf of Network Rail, and also to undertake the majority of the surveys using its in-house engineering teams.

Such a busy and complex area required much thought and consideration in planning and executing survey works while maintaining a fully operational rail infrastructure. To successfully carry out the planned works, Bridgeway appointed a project team to work in conjunction with Network Rail at its Euston site which included access planning, operational and technical leadership and the utilisation of multiple data collection, processing and modelling teams.

For the Bridgeway Geomatics teams, the works were broken down into four key areas:

» Survey strategy, data management and technical support;
» Euston Station pointcloud survey;
» Track and lineside surveys;
» BIM and 3D modelling strategy and production of models.

To assist in the management of survey data, production of standards, development of scopes and to offer technical support as and where required, an experienced client survey manager was appointed to work alongside the Network Rail project team. In liaison with the Bridgeway project managers, all parties were able to establish delivery protocols very early on in the process and ensure that the deliverables matched expectations through ongoing interaction and the development of open working practises.

One major part of the project was a full 3D laser scan of the entire station, including all platforms, Network Rail and London Underground concourses, car parks, parcel deck, back of house and basement areas, offices and the station perimeter. The sheer size of the site, coupled with issues surrounding interfacing with the public and working within a busy, thriving environment, led to a period of intense planning and development of new methodologies prior to the start of site works.

Key challenges to be faced included security issues surrounding accessing sensitive areas of the station, restricted access times front of house and operational areas, train timetabling, transfer and management of large datasets and, of course, the British weather when surveying the station facades and perimeter.

Key to the success of the project was engaging with the station management team and maintaining ongoing contact to ensure that every access opportunity was maximised. This, in turn, was supported by flexible working by the survey teams, using a combination of daytime, night time, midweek and weekend shifts to work around station operations, members of the public and other work groups. Additionally, new working methodologies were employed including improved on-site data capture techniques, nested registration of pointclouds and the introduction of additional QA procedures. Data was tracked, transferred and verified on a daily basis, using IT links from the onsite project office.

The scan data was captured over a period of four months, with approximately 1,900 medium-resolution colour scans captured and delivered in multiple formats and uploaded directly to the client Common Data Environment. Due to the overall size of the scheme, the pointcloud had to be broken down into manageable 5Gb datasets to allow efficient use for the design and asset teams. In key areas of the station, 3D wireframe and surface models were created, and the pointcloud was also used to extract infill data to update and expand legacy drawings already owned by Network Rail.

Lineside surveys

Perhaps the largest element of the Euston works were the track and lineside surveys, which involved the merging of multiple large and complex datasets collected using various equipment types and methodologies. The scoped works included track, topographical and gauging surveys to be undertaken between the buffers at Euston station and Primrose Hill tunnels, some 4km further north, with additional in-house GPR and drainage teams also employed at key stages.

Prior to any data collection it was vital to ensure that a robust survey grid was in place and, with that in mind, Bridgeway survey teams installed and coordinated a project grid at track level, including PGMs (permanent ground markers) and spigots throughout tunnels and bridges.

One key consideration for future works was that consistent and open access is severely restricted even within possessions, and therefore 360° mini prisms were installed in those challenging areas, ensuring that future survey teams would have sufficient accessible control to be able to work from. Additionally, a new secondary control baseline was required to close the network and enable the stations to be coordinated precisely and to a consistent grid.

Following on from the survey control acceptance, a full suite of tools was employed to accurately survey the position of the infrastructure along the route. Traditional high-precision total station measurements were carried out, alongside kinematic and static laser scans, with all of the datasets then merged to provide a full 3D environment which could then be used for modelling and data extraction. A 3D wireframe model was also extracted, providing a comprehensive yet manageable drawing.

As with all works on track, the primary consideration when undertaking the lineside surveys was how to best make use of the access available. Euston is a particular challenge due to the sheer number of crossovers, live lines and sidings and the presence of DC conductor rails. Often it was only possible to achieve two hours working time in a shift but, by working with the planners, station staff and other contractors and by using the most appropriate methodologies, the survey teams were able to ensure that maximum productivity was achieved while maintaining the focus on quality and accuracy.

Future benefits

Following the joint production of a BIM modelling strategy, Bridgeway is now working with Network Rail to model key areas of the station and to highlight the benefits that a full 3D parametric BIM model can bring to the project. Future benefits that are being explored are the incorporation of ground investigation AGS data into the model alongside the modelling of data derived from utilities surveys, which when combined would create an overall picture of any development and design proposal both above and below ground.

In order to deliver a project such as Euston, a joined up approach is essential from strategy and planning through to execution and delivery. This, combined with full integration into the Network Rail project team and a willingness to embrace new technology and ideas, has led to the successful delivery of a complex and challenging programme of works. In turn, the surveys undertaken to date should form the basis for the design, construction and asset management of Euston Station and it’s infrastructure for years to come.