Technical data warehouse

The definition of a technical data warehouse in the construction phase is an integrated information basis, which holds all technical data, consisting of drawings, lists, spreadsheets and technical specifications. It should be understood as an information pool where the project participants can get and retrieve knowledge about technical requirements of the project. Drawings normally capture the information for several technical and commercial departments on site.

A centralized kept up to date model based approach instead of drawing related work will reduce the effort for counting technical facilities in various drawings with several revisions. Of course the language of the field engineers is the drawings and they will stick to them, but for the technical offices on construction sites the model based solution (object orientated) should be preferred. Drawings can be created from the model. Object orientated has its advantages when changes have to be incorporated into the model. The change of one object will initiate a change to all related objects (AutoCAD CIVL 3D, Augustus 10 V12). The overall amount of changes can be find out in a fast a comfortable way, and the related departments subcontractors can be informed.

GIS can help to assist the workflow by many functions (see chapter 4 GIS functions) especially for the external or outside works (utility, facilities). The connection to the design will be generation of models with attributive information or at least drawings with attributive blocks, which can be imported to a technical data warehouse (GIS, Map Server, and Model Server) on site.

8.2.1 Type of technical data: drawings – lists – specifications

The technical information about an infrastructure project is captured generally in drawing files. These drawings are created either by the design department of the construction company or the tasks are delegated to design subcontractors. Partly the information is prepared by the client or he has delegated to a consultant company. The designing and preparing of the technical specifications which reflect the current state of the art for the realization of the project will be created by the consultant company.

Specifications give the clear information which elements or material should be used for construction, it will advise the way of construction and the quality investigations that have to be executed in order to prove the correctness of the build in element or material. Lists will be prepared from the construction company in order to organize the procurement of the items, which have to be installed (see figures 8.2.1a and 8.2.1b).

Figure 8.2.1a Example table of manholes and duct banks for procurement, New Athens International Airport [Hesterkamp]

Figure 8.2.1b Example database relationships of utility systems, New Athens International Airport [Hesterkamp]

In combination with the first draft design drawings and the specifications the construction company will prepare the detailed design drawings. The detailed design drawings reflect the specifications. The implementation will take place on site according to the construction method and the specifications for installation.

8.2.2 Ordered and submitted data from subcontractors

A major part of work for an infrastructure project is done by several employed subcontractors. Either they work for the design or for the construction. The task of a general constructor is to lead the members to successfully achieving the target of the project within the time and budget. In the sense of the model based set-up of new infrastructure projects the general constructor has to give odds, which describe how and with which attributes a part in the design should be produced and stored, to the subcontractors.

Another task a general constructor has to do is to settle a unique coordinate system, which can be a temporary local system for the site or a grid for a building. The transformation into national coordinates and the merging of parts from subcontractors into an integrated model will be done by the general constructor. A further task is the checking of the delivered drawings or parts of the model, which can be done with the assistance of new algorithms in the CAD software.

It might be a problem to follow all the versions of the delivered drawings during the design process and the implementation in the GIS model has its effort too, but at the end it will help to serve the up-to-date information needs of a construction site. An example of the use of GIS in combination with CAD during operation and design is given OCSD (Orange County Sanitation District). The use of GIS – here ArcSDE and ArcIMS – for a facility model and CAD – here AutoCAD and MircoStation – for the design task and the mutual exchange of data between both systems has gained advantages for the utilization of the staff and resources and has minimised the changes in the existing workflow (for further information see [BROWN]).

The contract administration department has to organize a new form of subcontractor contracts which have to regulate the access to the information platform and the duty of notification of changes and their implementation to the subcontractors work. Technical regulations for a model base approach could be done by the setting on hold of parts of the model, which are currently being changed. The general constructor has to inform the subcontractors. This task can be settled by automatically generated e-mail notifications to the subcontractors involved.

Figure 8.2.2a Example for combination of CAD and GIS in facility managing and design – construction process [BROWN]

8.2.3 Connection to procurement

One of the procurement department’s tasks on a construction site is to order material and facilities which are necessary within the construction workflow. The information about the parts which have to be built during the construction process will be evaluated by the works preparation group which is embedded in the engineering department.

Commonly the works preparation department will make an extract of the necessary elements, which will be needed for a certain construction phase within the time schedule. This information is gained from the drawings and summarised in lists or spreadsheets that are handed over to the procurement a certain time in advance. The procurement department will order from the dealer. The workload for the works preparation department can be slimmed down by using easy counting functions from GIS and CAD software.

8.2.4 Lack of easy integration of complex CAD files into GIS

The design works for an infrastructure project is moving in the last year more and more towards the three dimensional preparation of digital drawing respective models by CAD. The information content of the CAD drawing files has increased a lot. Next to the geometric information the description and the properties of a designed object is stored in the drawing file or is captured by a link to an external database. The complexity of the infrastructure projects and the available time for their design and implementation is the right challenge for CAD programs. The created objects have additional information e.g. kind of material, dimensions, volumes. The transfer into GIS of this additional information needs the support of additional software and modules; especially for the complex three dimensional objects and their attributes. An easy loading of complex 3D CAD files into GIS without losing the special applications object information is not yet possible, but is only a question of time. Web based solutions drawing up a new way of data exchange and interoperability. This might be a solution for the current time and in the near future: producing the data with complex application software and export to web based international agreed standard formats. The interfaces are available in various CAD and GIS software. The data pool will be the web-model.