LEVELS OF DETAIL ACCORDING TO YOUR REQUIREMENTS

The level of detail shown in the 4D model depends upon the purpose the model will be used for. There are no hard rules, but generally there are three categories; Bid Tender, Pre-Construction and Construction. It would be unusual to build a complete 3D model for a Bid Tender since the purpose is to show the process of construction, how the project would be undertaken by the construction company, and to demonstrate an awareness of the key issues and solutions to them. Accordingly the levels of detail can be broadly grouped into three categories, although a 4D model may contain a mixture of all three. The industry recognises three levels of detail as Level’s 1, 2 and 3.

Whatever level you choose to begin with, our 3D models can be reused or expanded should you later opt to extend to a higher level 4D model, or make use of any of our other services.


BID TENDER MODELS – LEVEL 1

Construction components are modelled in 3D as design spaces or zones within the site. These will correspond to the activities found in the construction programme. Elements are grouped together so that task durations (‘construction time’) within a particular zone, area or level may be shown in 4D. In its simplest form a floor by floor construction might be shown where a steel structure is modelled as levels and programmed as such. The model is built to show how these ‘activities’ relate to others in the adjacent or same zone. On a larger project, a Level 1 model might show how the construction of several buildings on the same site will be interfaced with each other.


PRE-CONSTRUCTION MODELS - LEVEL 2

These models show more detail so the components within a zone or area can be can be linked to the multiple activities found in the construction programme. They tend to show more detail for excavation and piling in the basements of large buildings. The planners vision of construction ‘zones or locations’ will be modelled as such so they may be visualised in 4D. Logistics are regarded as the key consideration for the delivery of a project and so they are modelled in more detail to show and communicate the process.


CONSTRUCTION MODELS – LEVEL 3

In a full 4D construction model the building and logistics will be modelled and programmed in detail. Here, for example, a steel structure would be modelled as individual pieces and programmed as such. The building services (M&E) are modelled in detail so that the installation of individual ‘systems’ can be programmed and shown. A construction model will include the sub-programmes of sub-contractors to show how they will interface with each other in the most efficient way possible.


CONTEXT MODELS

All 4D models will show the site in context with its immediate surroundings since it’s necessary to show roads, adjacent buildings and anything that might have an effect on the construction process. On larger projects this is shown in some detail so that road closures and traffic management can be seen in 4D. A key consideration might be to satisfy neighbours and local authorities that the build plan has accounted for its impact upon the community and that there are plans to minimise any disruption.


LOGISTICS MODELS

These models are included to communicate the construction methodology and win support from the customer, local government and adjacent businesses and residents. Logistics are perhaps the most important part of 4D as they show how the project will be built and delivered. By their very nature, the location of logistics items will change as the construction progresses. Therefore all the ‘elements’ must be modelled in 3D in each position they will be located at throughout the construction process. Items that are modelled can include the site set-up, hoardings, site offices, demolition of existing buildings, excavation, ramps, the position of tower cranes and hoists, scaffolding, temporary structures, drainage, enabling works, road access and any closures affecting vehicles and pedestrians.


MAIN PLANT & SERVICES

Main plant can be modelled in detail or as simple design spaces allowing them to be linked to the activities in the construction programme. Such items can include; lifts and motor rooms, risers, toilet pods, generators etc. It is unlikely that building services (HVAC, piping, containment) information will be available at the bid-tender stage and so they are generally modelled as design blocks with few activities. As more information becomes available from the sub-contractors and planners, detailed M&E models can be included into the 4D construction (level 3) model.