Raido Puust

Terrestrial laser scanning can provide high-quality, detailed point clouds, with state-of-the-art research reporting the potential for sub-centimeter accuracy. However, state-of-the-art research may not represent real-world practices reliably. This study aims to deliver a different perspective through collaboration with the surveying industry, where time constraints and productivity requirements limit the effort which can go to ensuring point cloud quality. Seven sizeable buildings’ point clouds (490 to 1392 scanning stations) are evaluated qualitatively and quantitatively. Quantitative evaluations based on independent total station control surveys indicate that sub-centimeter accuracy is achievable for smaller point cloud portions (e.g., a single building story) but caution against such optimism for sizable point clouds of large, multi-story buildings. The control surveys reveal common registration errors around the 5 cm range, resulting from complex surface geometries, as in stairways. Potentially hidden from visual inspection, such systematic errors can cause misalignments between point cloud portions in the compound point cloud structure, which could be detrimental to further applications of the point clouds. The study also evaluates point cloud georeferencing, affirming the resection method’s capability of providing high consistency and an accuracy of a few centimeters. Following the study’s findings, practical recommendations for terrestrial laser scanning surveys and data processing are formulated.

Digital construction is expected to reduce the high volume of waste and the labour shortage in the construction sector. The properties of hardened concrete used in 3D printing depend on numerous parameters within the manufacturing process. This study collected data using 208 specimens to measure the effect of the loading direction relative to the printing direction on the strength characteristics of printed concrete. The compressive strength was not significantly affected by the directions, but showed a 30% reduction from mould-casted strength due to lesser amount of compaction in the printing process. Flexural tensile strength showed a 14% reduction in one direction, possibly caused by heterogeneity due to the use of extrusion head with a 35% smaller diameter than the width of the layer. Splitting tensile strength was 14% lower when split between the printed layers. Splitting tensile strength is possibly 5% higher when PP fibres are oriented favourably.

Regular as-built surveys have become a necessary input for building information modelling. Such large-scale 3D data capturing can be conducted effectively by combining structure-from-motion and unmanned aerial vehicles (UAV). Using a RTK-GNSS equipped UAV, 22 repeated weekly campaigns were conducted at two altitudes in various conditions. The photogrammetric approach yielded 3D models, which were compared to the terrestrial laser scanning based ground truth. Better than 2.8 cm geometry RMSE was consistently achieved using integrated georeferencing. It is concluded that the RTK-GNSS based georeferencing enables reaching better than 5 cm geometry accuracy by utilising at least one ground control point.

Urban stormwater drainage systems (UDS) are severely affected by the changing climate bringing along inter alia more intense rainfall events. The conduits, usually having limited capacity, are unable to cope with these excessive flowrates. Therefore, measures must be undertaken to temporarily accumulate extra flowrates in order to avoid the flooding. There are several options available to tackle this challenge, e.g., low impact development (LID) solutions, best management practices (BMP), stormwater real-time control measures (RTC). In this study the efficiency of in-line and off-line detention tanks are analyzed. Moreover, new concept of smart in-line storage system is created and evaluated. This solution shows significant reduction in peak flow, economic benefit and is particularly suitable for the districts with limited construction space. The concept has been successfully tested in 10 ha dense urban development area in Estonian capital Tallinn.

The solution approach proposed in this paper is on the basis of trial-and-error methodology, using heuristic methods with simulation at the battle of background leakage assessment for water networks (BBLAWN). To achieve the optimal solution, customized researched tools were developed for water distribution system (WDS) optimization. These include subroutines for: optimization of water tanks levels to switch pumps on and off; estimation of the influence of the pressure-reducing valves (PRVs) on leakages, to make a decision whether there is a justification for adding a PRV to a pipe or not; calculation of leakages under different conditions; and replacing old pipes with new ones. For design decisions, commercially available tools were also used, carrying out comparison of various network structures (parallel pipe alternatives). The final result included the installation of 80 PRVs, the replacement of 370 pipes, and the change of 2 pump elements; the pumping schedule, on the basis of water tank level...

A simple graphical tool was developed, that finds the optimal combination of pumps and their rotational speeds for all possible working points for a pump battery. The tool was integrated into EPANET as well as EPA SWMM simulation packages. The tool allows us to analyse and optimize operation non-identical parallel pumps with different minimum and maximum frequencies for all possible working points. Pump characteristics and efficiency curves can be given in tabular format or as analytical functions of flow. Degradation of pump efficiency at lower rotational speed is taken into account, as well as motor and variable speed drive efficiencies at partial loads. The optimal solution provided by the tool was compared to measurements in two case studies. Our case studies showed 6.1–8.5% reduction in energy usage using the optimal parallel pumping control strategy compared to the currently used strategy, where all running pumps have the same frequency.