In the FINBIM work package, principles were defined to employ model-based designing (InfraBIM) into pavement design.
The prerequisite for BIM design is to gain information about the current state of the site. The most common way to gain this information is mobile mapping the site with equipment that has been installed into a vehicle (mobile laser scanner mapping). This mapping produces a point cloud chart, from which the inventory model of the site is analyzed and processed.
The current conditions of the site is determined with the inventory model , and possibly by using other measurements e.g. FWD, GPR. The needs for new pavement are designed based on the current state and specifications for the site. Based on e.g. the overall costs, we are able to optimize different paving procedures, and the extent to which they are to be employed (milling, levelling or laying new asphalt surfacing).
Model-based designs that exploit geographic information can be executed with machine-control procedures of different grades. In its most exact form, the machine is controlled by fully automatic machine control. Because the procedure is currently rather expensive and time consuming, we tested whether the machine control codes could be transferred into the site by using palmtops (PDA device). Then the location-based designs are realized by steering the vehicles manually.
During the FINBIM in numerous paving pilot projects mobile laser mapping, model-based designing and machine controlling were tested.
Based on the pilot site experiences we observed that mobile laser mapping can be used to calculate an exact, rich in information and illustrative 3D-model of the road surface.
Managing the model visually with the PDA device and it’s speciallly programmed interface in the site was successful. The data can also be transferred to an open Google Earth environment and viewed with generally available software. Model based design was successful in the various different environments that were tested. The condition and damages on the site are evaluated, and different realization solutions can be tested in the designing. The realizations can be optimized based on different criteria.
Experiences from the pilot projects proved that with the help of an exact initial data model, very exact mass calculations can be made based on the designed planning model. Modeling was able to produce exact cost evaluations for the construction already in the designing phase. Less resources were needed to manage the execution and the actual construction which reduced total costs.
The method enables a detailed longitudinal and latitudinal analysis of unevenness and depressions on the site. Exploring the alternative options allows evaluation of repair solutions, and for example focusing the available resources especially to problematic sections on the road. In addition, road safety increases and life span (maintenance cycles) lengthens more effectively than with traditional pavement principles, further reducing costs.
Transferring planning models into machine control system works well and the machine controlling itself runs well and accurately. Moreover, level milling was successful according to quality control calculations as well.
Example analysis of point cloud data.
The accuracy and effectiveness of mobile laser mapping will increase in the near future. It is also likely that the number of mapping realizers will grow. More instructions on the collecting of point clouds and other initial data, as well as on responsibility issues are needed.
Rut as a parameter can be determined from the mobile mapping data, and retaining it as a paving management parameter is advisable. In the future, it would be advisable to examine the possibility to replace profile measurements with mobile laser mapping.
In the future, it would also be advisable to investigate in more detail the replacement of IRI values with the point cloud based calculations of the longitudinal and transversal changes on the road.
The infrastructure design systems do not yet completely support the procedures required in asphalt paving design, e.g. different damage evaluations must be made outside the systems. The design standards for maintenance tasks should also be discussed and directed within the infra branch of business.