Level of development - BIM
- 1. Practical BIM- LOD was developed by a construction costing software company (Vicosoftware) and was used to make the process of estimating possible in BIM. Estimating involves human factor, but LOD makes BIM models do estimation without the involvement of human. - They developed the concept of Level of Detail o LOD 100 – not very definitive, but area/volume rate are accurate enough o LOD 200 – number of items in the model are correct, but they have to estimated individually o LOD 300 – items defined, actual cost can be used o LOD 400 – has supply data also, so can be used to assess payments for purchases - AIA redefined the term LOD to mean Level of Development to be used in reference to BIM - Renamed it so that it is not confused with amount of information, rather than the decisiveness of information Level of Development - It is a measure of how seriously you take the information represented by a BIM element - Different people perceive the information differently - to be able to work they require a certain level of details o To order something, contractor requires only the model number and manufacturer. But to install it, the carpenter requires the dimensions, material etc. So, for the same product - different details are required by different players - Level of Development “LOD” - LOD 100 – describing what it is; LOD 200 – its dimension; LOD 300 – its functions and options; LOD 400 – manufacturer and model; LOD – 500 LOD 400 + delivery details - Tells information what a particular person can use - Also a measure of the completeness of work- LOD 100= 20%; LOD 200= 40%... LOD 500= 100% Level of Detail - It is a measure of the amount of information provided – measure of quantity - Level of Detail “LOD” o Differently used by various agencies CIC (Penn State) called as Information Level of Details aka “Info”– A: size, location, material, object parameters; B: general size and location, object parameters; C: schematic size and location USACE M3 (Min. Model Matrix) called as Grade – A: 3D + facility data; B: 2D + facility data; C: 2D + text description AEC (UK) BIM Protocol called as Graded Component Creation- G0: Schematic; G1: Concept; G2: Defined 3D; G3: Rendered 3D o LOD Tables – tabular representation of LOD data; describes how information in BIM model will progress; how much information is usable at each stage of project etc Link between Development and Detail - Both are quite different but closely related and interdependent
- 2. - One cannot have a certain Level of Development if Level of Details does not exist - Without Details you cannot successfully visualize a product, and without Development you cannot order the right product. - Level of Detail – required more in the starting phase and decreases as project proceeds - Level of Development – required less in the starting phase, but increases as project proceeds - So, for clarity – LOD: Level of Development; Grade: Level of Details An LOD table is an attempt to record agreed responsibilities around a BIM Model. It sets the Division of Responsibility inside the BIM model. There are various LOD concepts which can be used. The author finds the US AIA E203 document which uses LOD and MEA (Model Element Author) in its Model Element Table as most appropriate. It allows to use the broad structure and concept, and gives flexibility change the structure, add new levels etc. and cater it to needs required by the project. It treats LOD not a set rules, but as a process. To make the best use of LOD we have to think about how we can make it meaningful to our project and the project team. - US AIA E203 gives freedom to create LOD table the way you like - Keep it simple enough to understand and complex enough to accommodate all the needs - Create multiple levels o Create levels even for sub tasks like inspection, QA/QC check etc. - Make multiple tables for different players containing the details they require - Treat LOD as a concept, not a rule. Tweak it to your own needs BIM: Measurement of design progress on large capital projects- In this chapter, the author delves into techniques that can be used to make implementation of BIM more effectively by focusing his attention on LOD. One of the key challenge that BIM practitioners face is the measurement of design progress in a BIM model. - BIM model tends to evolve unlike 2D drawings that follow linear fashion. So, different method has to be used for progress measurement in BIM - Analytical Analysis ability of BIM is useful in this case and author puts forward some analytical analysis techniques that can be used Setting up data collection now to enable progress tracking later:- - It begins with the definition of LOD. Different LOD levels should be defined. LOD 100, LOD 200, LOD 300, LOD350, LOD 400 and LOD 500 - As we move from LOD 100 to LOD 350 more and more details should be added to make the object more defined and certain - LOD should definitions can be customized - Intermediate LOD levels like LOD 350 should be created to enable better understanding and coordination between various disciplines. - Higher level of LOD like LOD 400 and LOD 500 have more details and can be used for prefabrication and field verification rather than design coordination. o LOD 400 and LOD 500 can be added later on, they are not necessarily required during design process
- 3. o This will save time during design phase Model Progression Table (MPT) - Accompanies customized LOD definitions - Unit Measurement per element per LOD should be added o Helps in keeping track of progress at different LOD levels o As it uses Measurement Units – it becomes easier – it is like integrating old and new i.e. 2D measurement for quantity to BIM - Grouping and layering of model elements o Layers and objects should be named to help designing and coordination o In addition, elements should be separated with their respective LOD layers LOD 100 level details in one layer, and then LOD 200, LOD 300 etc. level details are added in separate layer. All these combine to for the complete element - Schedule, categorize and link activities to model elements o Various phases like design/engineering, modelling, coordination, revision, re- coordination etc. should be categorized in the BIM model o Attach each of these phases with a WBS code o This helps track how much time and resources are spent in each phase Lack of sufficient effort during design/engineering phase causes revisions in the design, and then it has to be re-coordinated – loss of time and resources If revision and re-coordination for a particular activity is more, it means there was faults in its design, and thus, more time can be allocated to these activities in future to avoid it - Track inputs of productivity o People involved in BIM modelling should keep a time-log for keeping track of time they spent on different activities, WBS, LOD level etc. o This will help in knowing how much time was spent on a particular element – area of time wastages can be avoided to increase productivity Using data collected to analyze and measure progress by leveraging data analytics - Input hours tracked in time sheets - Model output tracked in LOD layers connected via WBS - Combining both (input hours and model output) creates a living dataset - Applying Data Analytics – different analysis can be done to track and measure BIM progress o Hours spent per LOD %age completion Gives visibility to effort spent in LOD per progress %age points gained o Hours spent per category per LOD %age completion Know if efforts spent were proportional or disproportionate to %age completion by LOD If disproportionality is there, then time spent can either be increased or decreased to enhance productivity If downstream activities (revision) takes more time, then time spent on upstream activities (design/engineering) can be increased which will result in less revisions downstream
- 4. o Vertical Analysis – the BIM “efficiency ratio” Hours spent redesigning, remodeling and re-coordinating are waste in system Lesser or no time should be spent here Greater time spent in initial design, modelling and coordination lead to less waste in system BIM efficiency ratio: Ratio of (time spent in initial design, modelling and coordination) to (time spent in redesigning, remodeling and re-coordination) o Horizontal analysis – the BIM “weighted average efficiency ratio Different phases were created in MPT by blending model elements with schedule activities through WBS By using this we are able to find time spent in each phase of the LOD o Initial design – more time spent on LOD 100s o Later phase – more time spent on LOD 350s Calculate BIM efficiency ratio per LOD This can be further used to create weighted average efficiency ratio This provides information regarding efficiency over particular time period of design as well as a trending measure over various phases of project o Using RACI (Responsible, Accountable, Consulted and Informed) matrix to allocate tasks to individuals RACI analysis of each individual across each activity done to spot overlaps and gaps Enhances clarity of individual responsibilities o Regression analysis and bench marking The data obtained from one project can be used to make improvements in future projects Data can also be used for selection of individuals like architect, engineer etc. o Linking element/activity to schedule of values Making progress payments like monthly payments to contractors Will require more effort in initial stages but very useful in later stages of project