Richard Palmer, rail sector manager at Dura Composites, explores how the latest 3D laser scanning technology can be used to preserve the UK’s Victorian rail heritage
Laser scanning is a way of visualising and exploring the structure, surface, fixtures or fittings of a building which is now finding new purpose in the preservation of some of the UK’s cherished Victorian railway heritage.
3D scanners use light and radar (LIDAR) to measure and record precise locations and distances to produce a point cloud file and help to capture a level of accuracy that would never be possible by hand.
Although the technology has seen considerable advances in the past few years, it’s not until now that it has been used as a cost-effective way of enabling rail infrastructure projects, particularly with regards to Victorian station canopies.
Traditionally an area that’s both difficult to reach and potentially disruptive to the station user, 3D laser scanning is now being successfully utilised to take accurate measurements of the precise detailing and structural properties of the entire canopy, to assist in its conservation, refurbishment or regeneration – without the need for intrusive surveying techniques or station closures.
3D laser scanning for rail station canopies
Accurately surveying the intricate features of buildings and structures has always been a challenge, but 3D laser scanning creates a more detailed representation than could be achieved with previous technology, and much faster too.
A 3D laser scanner can gather millions of data points per second, which in itself is astonishing, but from a health and safety point of view, it’s revolutionary. Often surveys require permission to access rooftops, or involve working at height in some form, for example in surveying a rail canopy at a station, so swapping traditional surveys for 3D laser scanning is a big step towards de-risking a project – both from a personnel perspective, and when it comes to the building itself.
With stations being in continuous use by passengers and staff, the scanning can be conducted without disturbing daily activities – and without the need to work at height. The danger of electrocution from overhead lines, and of causing damage to the physical structure and the dagger boards themselves is also eliminated, which is a huge advantage, especially when it comes to listed buildings and areas that are difficult to access.
Many of the dagger board designs are completely unique and in many cases, removal of the degraded timber boards may irreparably damage and eradicate the design forever. In 1977 there were thought to be over two hundred different patterns in the southern region of Britain alone (Reynolds 1977[i]), all with their unique charm and historic associations.
The scanning process captures every detail, meaning you get an as-built record to use as a basis for producing exact replicas in modern materials. In some cases whole sections may need to be replicated, and in others, the new material can be added to blend seamlessly with the old. At Dura Composites, we then use this as an opportunity to replace the old materials with high-performance fire-rated materials which require minimal maintenance and are significantly lighter in weight, putting less stress on the canopy structure itself.
3D laser scanning in the wider rail industry
Part of Network Rail’s responsibility is to develop the railway for the 21st century, while keeping an eye on preserving its built heritage. Being able to survey areas that need maintaining or developing without the fear of physically damaging them, therefore, is crucial.
It’s also simply an ideal way to demonstrate the end product and what can be achieved. Naturally the development work carried out on rail bridges, tunnels and stations has to alter its original construction in some way, but because of the powerful impact on people and the landscape, being able to do this sympathetically is important.
3D scanning allows the survey to be carried out without compromising the physical properties of the station, but the process also means that manufacturers can show and justify the use of replacing materials on a like for like basis, and highlight the benefits that come with these upgrades, such as a longer lifespan.
Beyond rail canopies, there are many areas of a station where 3D laser scanning is now being adopted. Work that needs to be carried out on footbridges has in the past (and present in many cases), meant a station had to be shut whilst a survey was carried out, but with 3D laser scanning, this can be undertaken with minimal disruption. It’s also ideal for awkward and difficult to access viaducts, for revamping of the track, as well as many other construction applications, like riser voids, roofing assessments, or planning approvals for new concepts.
Beyond the rail industry
Gaining permission for access to carry out surveys when dealing with listed buildings is particularly tricky, and so it’s not a surprise that 3D laser scanning on these buildings is already popular. Inaccessible sites and difficulty getting clearance has made this method mainstream, but it’s also useful for mocking up changes before committing to them.
For example, when it comes to shop fittings, understandably there can be reluctance to jump straight in and make changes, so adopting the laser scanning approach is a cost-effective way to experiment without investing fully in the proposed solution. The chance to test in 3D format first means money isn’t wasted, and confidence in the project is higher.
Regardless of industry sector, working with the models created from laser scanning is a great way to minimise waste, in terms of both time and budget. From a project management perspective, it reduces the possibility of problems further down the line, and can be used in conjunction with other technology to allow multiple parties to collaborate on a project.
3D laser scanning is becoming more accessible
Like anything in the manufacturing industries, the superior results achieved by 3D scanning are leading to growing confidence in this modern approach to surveying, and as the industry gains confidence in it, the technology becomes more accessible.
Where previously this technology would have been beyond realistic budgets for many, advances mean this is becoming more affordable, and there’s greater flexibility too, with options to rent rather than buy, providing scope to see how it works before investing.
3D laser scanning provides an excellent alternative to traditional surveys, from a safety perspective, as well as saving time, increasing accuracy, and speeding up approval processes. It’s a technology that can and should be used across most industries, but is most valuable where there’s a need to preserve the past, eliminating the possibility of damage, whilst also justifying recommended changes. These are all factors that will continue to propel this method into the mainstream.