Terrestrial laser scanning assessment of generalization errors in conventional topographic surveys

The technology of terrestrial laser scanning has widely been used in the surveying industry in recent years due to higher data collecting productivity compared to traditional tacheometric survey. The aim of this study is to assess generalization errors in topographic surveys of landforms on the basis of a large vegetation free semi-coke landfill hill with the relative height of 116 m in North-East Estonia. The numerical assessment of errors is proceeded by comparing a high-resolution terrestrial laser scanning (TLS) 3D surface model with surface models generated from the sparser data steps (10, 20, 30 and 50 m). The 10 and 20 m data step surface models yield discrepancies within ± 20 cm. The 30 m data step models revealed slightly larger differences. Expectedly the largest elevation differences reaching up to 2.5 m were associated with the 50 m point step

Geodetic surveying studies for civil engineering students at Tallinn University of Technology

Studies in the Tallinn University of Technology are based on a modular system, where geodetic surveying comprises a self-contained study module in the curricula of all civil engineering specialities. Due to geodetic surveying being taught to all first year students of civil engineering, it serves as a touchstone to test a student's suitability for an engineering specialism. Future civil engineers are taught basic geodetic measurements and how to use optical theodolite, levelling instrument and laser level. The paper gives an overview of geodetic surveying lectures, laboratory classes and field survey camp. Teaching and assessment are based on learning outcomes. Students who have passed the exam are allowed to participate in the summer field survey camp, the aim of which is consolidating the knowledge acquired throughout the year and practising teamwork

Combined 3D building surveying techniques – terrestrial laser scanning (TLS) and total station surveying for BIM data management purposes

Building information modelling (BIM) represents the process of development and use of a computer generated model to simulate the planning, design, construction and operation of a building. The utilisation of building information models has increased in recent years due to their economic benefits in design and construction phases and in building management. BIM has been widely applied in the design and construction of new buildings but rarely in the management of existing ones. The point of creating a BIM model for an existing building is to produce accurate information related to the building, including its physical and functional characteristics, geometry and inner spatial relationships. The case study provides a critical appraisal of the process of both collecting accurate survey data using a terrestrial laser scanner combined with a total station and creating a BIM model as the basis of a digital management model. The case study shows that it is possible to detect and define facade damage by integration of the laser scanning point cloud and the creation of the BIM model. The paper will also give an overview of terrestrial laser scanning (TLS), total station surveying, geodetic survey networks and data processing to create a BIM model. First published online: 24 Oct 201

Determining Ranges and Spatial Distribution of Road Frost Heave by Terrestrial Laser Scanning

The technology of terrestrial laser scanning has evolved rapidly in recent years and it has been used in various applications, including monitoring vertical and horizontal displacements of constructions but significantly less in road frost heave assessment. Frost heave is categorised as one of the main causes of pavement surface damage in seasonal frost regions. Frost heave occurs in wintertime and in early spring at the freezing process of the ground supported structures such as roads. The major change in the structure is the increase of soil volume due to freezing of its water content. This contribution assesses vertical displacements caused by frost heave on a road using novel terrestrial laser scanning technology. The study emphasises on benefits using the technology in determining accurate magnitudes and spatial distribution of frost heave of roads. The results of case study revealed uneven spatial distribution of frost heave, which may also be an evidence of relatively poor road design quality. Therefore it is also advisable using terrestrial laser scanning in applications such as quality assessment of existing roads and in the pre-reconstruction design stage for detecting any frost heave sensitive areas in existing embankments

Geodetic Monitoring of Bridge Deformations Occurring During Static Load Testing

Terrestrial laser scanning technology has developed rapidly in recent years and has been used in various applications but mainly in the surveying of different buildings and historical monuments. The use for terrestrial laser scanning data for deformation monitoring has earlier been tested although conventional surveying technologies are still more preferred. Since terrestrial laser scanners are capable of acquiring a large amount of highly detailed geometrical data from a surface it is of interest to study the metrological advantages of the terrestrial laser scanning technology for deformation monitoring of structures. The main intention of this study is to test the applicability of terrestrial laser scanning technology for determining range and spatial distribution of deformations during bridge load tests. The study presents results of deformation monitoring proceeded during a unique bridge load test. A special monitoring method-ology was developed and applied at a static load test of a reinforced concrete cantilever bridge built in 1953. Static loads with the max force of up to 1961 kN (200 t) were applied onto an area of 12 m² in the central part of one of the main beams; the collapse of the bridge was expected due to such an extreme load. Although the study identified occurrence of many cracks in the main beams and significant vertical deformations, both deflection (–4.2 cm) and rising (+2.5 cm), the bridge did not collapse. The terrestrial laser scanning monitoring results were verified by high-precision levelling. The study results confirmed that the TLS accuracy can reach ±2.8 mm at 95% confidence level