Clash Detection in the field of virtual construction modeling is one of the most important parts of the BIM Life cycle. This particular process forms the crux of BIM and its sole existence. Clash detection is a process which defines “detecting clashes, interference or collisions that occur in the modeling owing to close placements or clashing of components within a single discipline or multiple disciplines such as Architectural and MEP or Structural and MEP etc. We can detect clashes, collisions or interferences prior to the actual construction process which saves time and money both within the construction process.

Clash detection services are used for the constructability review of a building. This assists the MEP consultant to find issues that may pose a threat to the accuracy and precise construction. This process helps in analyzing issues that may delay construction, cost more than the actual budgeted amount and other productivity issues in the actual construction.BIM Clash detection can be accomplished through software such as Revit, Navisworks, ArchiCAD, Tekla etc. Revit and Navisworks are well known while some software is lesser known and are not very user-friendly. There are a lot of advanced features like the ability to create clash rules, conducting clash test and so on.

Name: Clash 01
Distance: -0.189m
Image Location: Test 1_files\cd000010.jpg
HardStatus: New
Clash Point: 19.312m, 13.884m, 38.344m
Grid Location: A.4 7-6.6 : T/ WB PLATFORM LEVEL
Date Created: 2017/7/2005:29:40

Item 1
Element ID: 303749
Layer: T/ WB PLATFORM LEVEL
Item Name: Concrete, Cast-in-Place gray
Item Type: Solid

Item 2
Element ID: 1650695
Layer:
Item Name: Generic Models 7
Item Type: Solid

Name: Clash02
Distance: -0.184m
Image Location: Test 1_files\cd000011.jpg
HardStatus: New
Clash Point: 24.062m, 24.961m, 31.191m
Grid Location: A.1-6.9 : GROUND LEVEL
Date Created: 2017/7/2005:29:40

Item 1
Element ID: 286168
Layer: CONCOURSE LEVEL
Item Name: Concrete, Cast-in-Place gray
Item Type: Solid

Item 2
Element ID: 1466403
Layer: GROUND LEVEL
Item Name: Iron, Ductile
Item Type: Line

Let us discuss some basic clash detection features and how clash detection is performed

Clash detection services is a timed process that is performed using a set of predefined elements. This test has a set of elements which is initially checked to identify interferences. They need to be validated initially to check the intersections and clearances. The best way to plan the clash test is to develop a matrix that will help the modeler or the MEP consultant to define the groupings of the different elements and subsequently prioritize the construction plan and the delivery schedule.

Arranging the clash test according to a specific order is very important and critical in model updating. There is a risk of redundancy and delay in case the clash test are not arranged in a specific manner prior to the clash detection test.

There is another term called “Clash rule” in the BIM clash detection process. The definition of clash rule is very simple. There are some specific rules to choose components or object that needs to be included in the process of clash test. Prior to the selection of the clash rule, the MEP consultant should check the entire model and see if the order of selection is maintained as required. Also, it is important that the naming conventions of the object are as per the IFC standards set by model sharing.

Next step in BIM Clash detection process is generating Clash Report from Naviswork. This report is very important for the stake holders, MEP consultants and the Design team who have developed the design drawings and the models. This report is extracted in HTML, PDF or XML format, rather any format that is readable. It is a user-friendly way to share issues, clashes or collisions that can be resolved later. However, this report also contains interference or soft clashes that are not very prominent and need not be resolved. Hence it is vital to track the issues diligently before working on the clashes to resolve them.

Clash detection report is a good way to share data about the interferences however there can be other reporting systems that different companies may like to follow. BCF or BIM Collaboration format is an open format developed recently. It is extremely productive and helps in analyzing other factors like clash location etc. Issues can be collaborated and shared across multiple platforms.

We can follow some general rules or guidelines while performing MEP BIM Clash detection.We should always resolve big clashes first. Generally structural or plumbing components may be the one to clash and they cannot be modified or moved. Hence we then need to resolve the clashes by moving components that can be easily moved. Apart from looking at major clashes, one can also look at the tolerances and the one that is mobile. We can run clash detection test on different sets specifying tolerances.

In summary, MEP BIM Clash detection is one of the most important parts of the BIM coordination process has helped the construction industry in reducing costs and increasing productivity in a great way.