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From CAD User AEC Magazine Vol 22 No 3 - FEBRUARY/MARCH 2009
Construction sequencing and clash detection provide the answers for infrastructure modelling, says Autodesk's Jack Strongitharm
Nowhere do the words: 'credit crunch', 'recession' and 'economic austerity' have greater resonance than in the construction industry. Recession in the UK may only have became a reality on 23rd January 2009, when the Office for National Statistics revealed the second consecutive fall in GDP, but for the more visible sectors of the construction industry housing, hotels and commercial buildings it started way back in 2008 when their industry came to a standstill.
What is less widely reported is that the worldwide infrastructure boom continues unabated. Much of the industrialised world faces the challenge of crumbling infrastructure; the legacy of the postwar construction boom - the networks of roads, bridges and railways that facilitated massive economic growth - is an infrastructure well past its 'use-by' date. Even the less developed 'tiger' economies, whilst hit by the global financial crisis, continue to experience exponential population growth and urban migration, all of which leads inexorably to long-term infrastructural demands.
One of the newly-elected US President's first pledges was to target the creation of
2.5 million jobs through infrastructure spending, perhaps mindful that a declining infrastructure is indicative of a second rate country. In the UK, it's believed that the Government will bring forward infrastructure projects worth around £3 billion, and contractors working on major projects like the widening of the M25, Crossrail and the London 2012 Olympics are also being asked to fast-track their programmes. Whilst all of this sounds very positive for the many firms comprising the infrastructural food chain, the worldwide economic downturn will have a far-reaching implications for the way in which they
operate from now on.
TRANSPARENT AND ACCOUNTABLE
For a start, all these firms will become increasingly accountable; governments may have agreed to fund these massive projects but they will also begin to demand that they are carried out as a fully transparent and collaborative process that is light years away from the working practices used to build the infrastructure they will replace.
Projects have become increasingly complex, and the many joint ventures typical of today's infrastructure projects mean that a plethora of construction- related skills - project logistics, civil engineering, highway and railway engineering, tunnelling, mechanical and electrical engineering, even specialist systems technologies - must all work together with a common goal rather than as discrete entities with a separate agenda.
POWER OF THE 4TH DIMENSION
For almost two decades, most of the world's buildings and infrastructure have been designed using CAD applications. The subsequent development of 3D building information modelling (BIM) model- driven design to create an intelligent and interconnected representation of real world objects - has reduced design and construction costs, increased the speed of delivery and reduced downtime costs.
Today, the amalgamation of all of these developments with 4D can improve quality and also bring these projects to fruition even faster and more cost-effectively than ever before.
With 2D, we had drawings on paper, but these were just lines and only provided a location for each element in the design. 3D gave the design perspective, providing
height and depth for each object, thus alerting the designer to interference or clash between components. Today, 4D has also built time into the equation.
By factoring 4D - or time - into the process, a contractor can allow for the fact that some elements of the construction must be in place before others. He can ascertain that deliveries of materials made at certain stages will be sufficient for the project to reach the stage at which the next delivery will occur, or even allow for the creation of temporary works, if necessary, so that traffic can still be maintained throughout the project.
Until recently, these tasks would all have been carried out on an ad hoc basis with the frequent hiccups and delays inherent in such a method. But by using civil design software like AutoCAD Civil 3D, together with Autodesk Navisworks Simulate or Manage, it is possible to automate these tasks and ensure - whether at design stage or during the sequencing of events on site that errors can be minimised and that the right thing is built in the right place, at the right time.
When all the designs comprising the project are combined into the single model or faithful Navisworks whole-project view, it becomes possible to walk around the buildings or to drive along the road, as well as to examine the underground services, inquire about objects, send reports to the designers, create animations and even publish the model on the internet or distribute it widely for viewing using a free viewer called Freedom. Even from within Navisworks, from any view, you can switch back to the same location within Civil 3D to find the same area that needs attention.
SEE IT BEFORE IT HAPPENS
So how would this work in practice? Take an example of a new building development. The civil engineers are designing the ground works, car parks and access roads. They have made enquiries into the utilities and have modelled the underground services from the plans received. However, the civil engineers are working for a different company to that of the building's architects, so how can compatibility be ensured?
If the project managers of the new development take both the architects' and the civil engineers' design packages and load them into Navisworks Manage, using the clash detection facility, they find that one of the pile foundations of the building would hit a high voltage electric cable that is running through the site. Thus warned, they can then instruct the civil engineers to work on a utility diversion with the electric company. Then, they update their model to show the new location of the diverted electric cable and the clash has been resolved - all before it ever happens. If this principle is applied throughout a project, huge time delays and additional costs can be avoided and the safety of the building crew is ensured.
PROTECTING INTELLECTUAL PROPERTY
Of course, many design professionals fear that sharing data may pose a risk to their intellectual property as the AutoCAD Civil 3D DWG file can be simply loaded into Navisworks. Not so - designers need only provide a NWD file exported from Civil 3D or Revit, for example, which is a fixed file that can only be viewed in all Navisworks products; NWD files are secure, compact and streamable.
In the past, pulling it all together would have involved using Ghannt charts and the critical path of a project was located using software like Microsoft Project and Primavava, but this did not necessarily link the plan that was in the designer's head or on the 2D plan drawings.
Using Navisworks Simulate or Manage, the project can be pulled together automatically; all the object data from the existing Civil 3D and Revit can be linked automatically into the existing construction sequence and to descriptions in the sequencing chart. This means you can incorporate all those temporary works and even deliveries to site and ensure there is sufficient room to store materials or that there is access to the relevant part of the site at that time.
Whilst many of the design and construction companies have already invested in AutoCAD Civil 3D to speed up design and drawing time and to improve accuracy on projects, taking the next step to 4D project review with Navisworks and getting the project right before it ever happens is a step that has not yet been realised by the majority. Even now, the economic environment for civil engineering projects is changing and will continue to evolve as the pace of worldwide infrastructural development accelerates; firms that expect to be part of it should take note.
For more information, a short video demonstration of AutoCAD Civil 3D and Navisworks can be seen at http://uk.youtube.com/CivilFromtheGroundUp
Visit: www.autodesk.co.uk/civil & www.autodesk.com/navisworks for further details
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