Building information modelling & practical application
Infrastructure in 2014: BIM puts design into the fast lane
Building information modeling is evolving fast. It is becoming the norm in railways roads and utilities.
A complex roof structure and tram stop for the Victoria station in Manchester, layout of pipes, tanks and roads for water and waste treatment plants and the transformation of the M60 and M62 into a “smart motorway”, with all-lane running, are among a series of projects applying the 3D model and information practices of building information modelling (BIM) at consultant Hyder.
Each work area is complex in its own way but perhaps the most “advanced” is the design, fabrication and later construction of a new steel roof for Manchester’s Victoria railway station. The £16M structure is part of an overall £44M revamp of the nineteenth century station to upgrade the existing facilities and, says client Network Rail, allows for future expansion of the station. Work includes an improved concourse, a new tram stop for Metrolink and a refurbishment of the Grade II listed Victorian buildings.
But the star feature is undoubtedly the new steel framed transparent roof which sits on the side of the buildings over the rail platforms in a curving right angled form known as a ‘Torus’. It is glazed, not with glass, but the lightweight ETFE or ethylene tetrafluoroethylene. The complexity lies in the shape of the structure which “curves in every direction,” says Hyder project director Andrew Dugdale. “It has a cross section like an ellipse, which transforms radially.”
The construction team for the project, which includes steel fabricator Severfield-Watson and contractor Morgan Sindall, decided to work with a 3D model from the tender stage onwards says Dugdale. “That means Watson and Vector Foiltech, who supply the ETFE, and Hyder could all work off the same 3D model in collaboration,” he says. Formats for file exchanges were agreed around those from Autodesk Revit which Hyder used for drawing the initial structural model. “That was analysed with Robot, also from Autodesk,” Dugdale adds.
The rail lines were modelled in Bentley Systems Rail Track software because of the complex curves needed, and were then imported to the model.
Severfield-Watson then took the assembled model into Tekla Structures, another “intelligent” program, which originated in steel frame design.
Using this Severfield-Watson then produced a highly detailed model of the steel which “showed every bolt, shim and steel plate,” explains Dugdale and from which it was possible to export the factory fabrication information directly.
The aggregated models were further developed then by the contractor.
“There are 43 different stakeholders and many are not engineers, so seeing the design this way allows much better communication”
Andrew Dugdale, Hyder
“They are using a program called Vico which can bring the models together and also ties with time line and cost information,” says Dugdale. Clash detection can spot and eliminate difficulties before working on site and method run-throughs. “They are also using it for health and safety issues and construction sequencing,” says Dugdale.
“It all allows us to work in a new way, much more linearly, when you have a true 3D model,” he says, “from structural analysis to model to drawing.
“Seeing the 3D model as you go is useful for the designers and for reviewing the design with everyone else. There are 43 different stakeholders and many are not engineers, so seeing the design this way allows much better communication.”
These coordination and communication aspects of BIM are also highly applicable in the water and waste treatment sector, says Hyder senior civil engineer and BIM specialist Ben Harries. Hyder works for a significant range of clients including Severn Trent Water, South West Water and Thames Water.
“We use a wide variety of software packages, like Revit Structures, Plant 3D, Autodesk Civil 3D and Revit MEP to build the models, which are then often brought together using Navisworks.” The models are useful for a wide range of others tasks too, from clash detection to quantity take-offs for the contractor. A range of file formats is used though he would like to see it settle on a common standard, possibly the .ifc format.
At present a lot of the as-built information comes in 2D drawing form, Harries says, although he looks forwards to a time when engineers remodelling or upgrading a treatment plant can examine a full 3D model of the “as built” information. Such models are now becoming the output from BIM projects.
Hyder is developing its own BIM understanding at present he says “and BIM itself is not static but rapidly evolving, along with the software”. One area Harries thinks will develop is combinations of BIM models and Geographic Information System (GIS) data, though it is “early days”.
This helps understand issues like flood risk; he would like to see a better capability in software to incorporate analysis tools within 3D models, so when changing pipework, for example, flow assessments could be part of the model itself.
But Harries points out that some of the intelligence in software is already highly useful within object-based software programs where “a column ‘knows’ it is part of a wall rather than just being a collection of lines and surfaces.”
“Revit,” he says, “is currently the weapon of choice.”
Its capacity to build parametric objects offers a host of future possibilities in the form of ready-designed components and items from suppliers that come with their own software description.
He emphasises how use of a 3D model, with fly-through and viewing from any angle, transforms how design and construction teams discuss and examine projects. “Before it would be a pile of 2D drawings on the table and it is not always easy to spot issues even when you are used to them. Using 3D visualisation we can bring more people into the design team, including the operations and maintenance teams. They can point to potential difficulties in carrying out their particular jobs - so you engage site level users in the design work at an earlier stage.”
More formal public consultation has been a key aspect of BIM use in the infrastructure sector, says Hyder senior technical director Steve Davies, who has been working on the M60/M62 Smart Motorway project for the Highways Agency. The project runs from Manchester’s ring road onto the Leeds Pennine motorway.
The scheme involves improvement of 27km of two motorways using a combination of all lane running and controlled motorway. With all-lane running, the existing hard shoulder becomes a fourth traffic lane; emergency refuge areas are created at intervals for vehicle breakdowns, but the concept relies equally on a much tighter monitoring and management of the motorway to detect any breakdowns via road loops, and frequent CCTV points. Variable message signs and gantry mounted signals then allow lanes to be closed or opened quickly.
“The system is different to the M42 peak hour use of the hard shoulder,” says Davies, “as the four lane running is continuous. And it is actually slightly easier to control as it avoids regular opening and closing of the hard shoulder.”
But controlled it must be and that means installation of significant additional road signings and monitoring points, with new gantries, some cantilevered and some full span of the road.
The visual impact of all this has to be assessed and be shown to the public; one of the first tasks for the Hyder/Halcrow design joint venture for the project has been building a viewable 3D model, which it has been using in several public exhibitions during November.
“The model allowed us to, firstly, produce a video run-through of the length of the project from the driver’s eye viewpoint, and then to show before and after images of the road from any particular position along the route so that any householder could ask to see how the road would look from his or her location,” says Davies.
The model road surface geometry and terrain was built up using Bentley MX from survey data, Lidar and terrain and road data. To this was added signage and lines, and the new gantries, for the moment as simple but accurate images created with Photoshop, but later to be brought in as the steel designs become available.
“We have been through the initial learning curve and are now pushing the boundaries of the software”
Andrew Dugdale, Hyder
Such visual representations are not new as such but in the past they have been made with a virtual reality image programme such as 3D Studio Max. While offering photorealism, such representations are not at an engineering level of accuracy. “The difference now is that the model is the design and can be updated quickly as it changes,” says Davies.
It also passes on to become the basis for the next stages of the work integrating various other design data such as drainage, which was not required in the public consultation.
The whole is aggregated in this case using Bentley’s i-model system, which uses Bentley Navigator. Inside that, clash detection and model collaboration can be achieved. It was also the basis for rendering the model for the public viewing, using the in-built software viewing “engine”.
BIM work in infrastructure is more demanding in some aspects than buildings, because of the sheer size of the models needed, in this case for a 27km long motorway-width corridor, and because of the complex nature of the curves and alignments on roads.
Hyder says the public consultation has gone well, however. It now moves on with the full design work, adding in the below ground elements that were not required for the public viewing. These will be the basis for the contractor’s work, due to begin next summer, and ultimately the data to pass on for asset management.
Hyder’s commitment to using BIM on all relevant projects shows that building information is becoming equally important to infrastructure projects and is no longer the exclusive domain of buildings. As Dugdale sums up: “We are now using various BIM enabled products throughout the entire life cycle of projects. They give us accurate visualisations at the concept stage, accurate engineering during design and construction and finally bring the as built information together.
“We have been through the initial learning curve and are now pushing the boundaries of the software. All our BIM projects are now benefiting from significant cost savings.”