Managing Multiple Clash Tests

Managing Multiple Clash Tests

In this, the next of our series of blog posts about making the most of Clash Detective, we’re going to cover the use of multiple clash tests. Now that we have shown you how to use rules to minimize false positives and use grouping, filtering and sorting to manage the results of each individual test, we’re going to talk about how you would want to scale this up to a project level and use and manage multiple tests.

Multiple clash tests jumble Navisworks

Depending on your role and industry you may have different schools of thought on the best way to do this, and there is no ‘correct way’, just what works best for your project, the level of input needed from various stakeholders, and the timescale you need to do this in. Here I’m going to go through a few of these schools of thought to give you a few options that may work for you.

Clash the BIG stuff first

In a project where you are bringing many disciplines into a single digital mock up, you will want to make sure that the ‘big’ things don’t clash, as these will be the things that cost the most money to put right. Generally this will be structural work, but it may include underground pipes, tunnels, sewers, or existing structure that cannot be touched or moved. Then you can move through the disciplines to the work that can be more easily and cheaply changed.

Reducing tolerances in steps

Another way to work through clashes is to look at those which need most movement to resolve first, and then reduce the tolerances of the clashes. Typically you would run these as multiple tests so you can see if any changes to the model reintroduce larger clashes e.g. Setting up ‘Architecture vs MEP > 1ft’, ‘Architecture vs MEP 1ft to 6in’, ‘Architecture vs MEP 6in to 3in’, ‘Architecture vs MEP 3in to 0’, ‘Architecture vs MEP insulation‘. Here you can work to varying tolerances at once and then set up additional clearance clashes to ensure there’s enough room for insulation, or gaps needed for access, looking at each test with the aim of ‘getting to zero’ then working on the next tolerance.

By level or section

Working through a project level by level, or splitting up the model into sections such as wings of a hospital or groups of rooms, can allow you to show visible progress in coordination meetings and split the work into bite size chunks, or you can work through basement levels that will be built first then work through higher levels whilst the project is already underway. New features like Revit Grids and Levels appearing in the clash results will help you refine the clash results to a precise location in the building. You should ensure that if you use this method that you cover the overlap between levels and also ensure that you test against objects not assigned to a level, or that you cover multiple sections.

Pre-fabricated comes first

There’s a number of reasons why this is a good idea. If something has been fabricated off site then the likelihood is that it cannot be changed later, or if it can, could it be done more cheaply with less risk in a factory environment than on site. There’s may also be longer lead times with pre-fabricated goods than with other components that can be created or assembled on site, getting these finalized as early as possible prevents delays later on.

Ad hoc tests

There’ll usually be a need for testing ‘on the go’ with unusual or site specific scenarios or just sanity checks against issues that need to be double checked when in doubt, we encourage you to use these in addition to some formalized testing. If you have some sort of order to the rest of your testing that covers the majority of common scenarios then you should only need to do a few ad hoc tests to make sure everything else is covered. If you find most of your tests are ad hoc for each project then it may be worth taking some time out to work out if there is a way to provide some order to the madness.

Here’s the next of our video playlist showing you how to create and use multiple playlists.

It is likely that your eventual approach will be a combination of some or all of these methodologies or some completely different ones, do you have different ways of managing your tests? We’d love to hear from you, any feedback you can give us will be passed to our development team for future consideration. Just with how you do things.

 Posted by  on 09/28/2012



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