Action TU1208

Civil Engineering Applications of Ground Penetrating Radar

COST Success Story

Tu1208 Case Studies



Archaeology and cultural heritage


Stonehenge, United Kingdom


These research activities were mainly carried out by the Ludwig Boltzmann Institute of Archaelogical Prospection and Virtual Archaelogy (AT), in cooperation with the University of Ghent (BE), as part of the Stonehenge Hidden Landscapes Project (


In 2014, an ECI from the University of Ghent carried out a 2-months STSM in the Ludwig Boltzmann Institute; the STSM focused on the analysis and interpretation of GPR and electromagnetic-induction (EMI) data collected by the two research teams in Stonehenge. The cutting-edge results achieved during this STSM proved the high potential of combining EMI and GPR for detecting subsurface structures and characterising soil variations at Stonehenge.


GPR: 16 channel 400 MHz MALÅ Imaging Radar Array (MIRA) with 8 cm channel spacing.

Main reference:

See also: STSM 4: "Reconstructing Prehistoric Environments at Stonehenge with Multiple Electromagnetic Survey Methods"


For more information please take contact with Dr Immo Trinks. (


Carnuntum, Austria


Carnuntum is a Roman town located about 30 km south-east of Vienna, in Austria. It extends over an area of about 5 km2. Research activities in this archaeological landscape are mainly carried out by the Ludwig Boltzmann Institute of Archaelogical Prospection and Virtual Archaelogy (


Extraordinary results are being collected, since 2011. This complex case study represents the most advanced example of large-scale archaeological prospection using GPR multi-antenna multi-polarisation systems; it is unique throughout the world, for its completeness and dimensions. The entire Carnuntum has been mapped in great detail, by using different radar systems.


A virtual model of the town has been realised. The achieved results clearly show that high-resolution GPR measurements are of primary importance for the detection, mapping, documentation and investigation of the buried cultural heritage in three dimensions.


Advancements and updates concerning this case study were presented and discussed during TU1208 Meetings. The case study was selected to be presented during the opening session of the 15th International Conference of Ground Penetrating Radar (GPR 2014).


GPR: 16 channel 400 MHz MALÅ Imaging Radar Array (MIRA) with 8 cm channel spacing.

Main reference:


For more information please take contact with Dr Immo Trinks. (


St Leonard’s Crypt in the Wawel Cathedral, Poland


The Wawel ensemble, including the Royal Castle, the Wawel Cathedral and other monuments, is perched on top of the Wawel hill immediately south of the Cracow Old Town, and is by far the most important collection of buildings in Poland.


St. Leonard's Crypt is located under the Wawel Cathedral; it was built in the years 1090-1117 and was the western crypt of the pre-existing Romanesque Wawel Cathedral. The crypt hosts the tombs of the Polish kings and several Polish heroes. Pope John Paul II said his first Mass on the altar of St. Leonard's Crypt on November 2, 1946, one day after his priestly ordination.


In May 2015, TU1208 organised a TS on the “Applications of Ground Penetrating Radar in urban areas: the sensitive case of historical cities,” hosted by the Cracow University of Technology (PL). Trainers and Trainees had the great honour and privilege to carry out the practical sessions in St. Leonard’s Crypt, in cooperation with the companies Restauro (Toruń, Poland) and Geoservice (Athens, Greece).


For the first time, a GPR was used in the Wawel Cathedral. Despite the limited time at our disposal, we obtained interesting results: for example, we found out that the tomb of Bishop Maurus (which is the earliest grave in the crypt) is shifted with respect to the inscription placed in the middle of the crypt and supposed to indicate its position; moreover, we could detect large cavities which presence was unknown, and estimate their size.


GPR: CX-12 GPR pulsed system of MALA Geoscience.

Main reference:


For more information please take contact with Prof. Lara Pajewski. (


Inspection of statues in the park of the Łazienki Royal Palace, in Warsaw (PL) and in the Archaeological Museum of Athens (EL)


These are unique case studies, as the inspection of statues is a new application of GPR.

The Łazienki Royal Palace is located in the largest park in Warsaw, which occupies over 76 hectares of the city center. It is also called “Palace on the Water” because it is build over an artificial island, on a lake. Several statues are present in the park and GPR was successfully used by the Action to investigate their inner conditions, in cooperation with the companies Restauro (Toruń, Poland) and Geoservice (Athens, Greece).


In the National Archaeological Museum of Athens, GPR was used to scan the marble statues of the “Antikythera Shipwreck” collection. This collection is composed by underwater findings, coming from the bottom of sea close to Antikythera Island; it includes the famous “Mechanism,” considered as the first computer in the world. The statues of the collection were exposed to sea erosion for more than 2000 years and during the underwater excavation many parts of them (e.g, hands, feet) were damaged or broken.


In order to deal with this, the conservators used metallic joints to assemble again the statues. In September 2015, this collection started to travel across European countries to be exposed in many museums, the first destination was the Museum of Basel (Switzerland).


GPR measurements were carried out by the Action, in cooperation with the company Geoservice, to evaluate the inner conditions of the statues and estimate their static capacity, prior to send them to Basel.

These activities were presented and discussed during COST meetings and Training Schools.


GPR: CX-12 GPR pulsed system of MALA Geoscience.


For more information please take contact with Mr Klisthenis Dimitriadis. (


Tholos Acharnon Tomb, Acharnes, Greece


The Tholos Acharnon tomb is a magnificent Greek monument belonging to Mycenaean culture (13th century B.C.), situated north of the capital Athens, in the city of Acharnes.

It was excavated by the German Archaeological Institute in 1879: Tholos Acharnon tomb was built to receive members of one of the most important families of the region, and treasured many of their belongings such as gold and silver jewelry and bronze weapons, now displayed in The National Archeological Museum in Athens.


Due to the great historical importance of this monument, the assessment required high-resolution and non-destructive methodologies: that is why GPR was used to investigate the tomb’s complex structure.

In particular, the radar survey aimed at both identifying buried objects of interest and detectioning specific zones where further restoration and maintenance should be recommended.


The survey covered the different parts of the monument: the corridor (Dromos), inside the tomb and the tumulus.


The assessment of the Dromos was mainly focused on studying the subsoil, looking for hidden objects through different radar lines.


The main objective of the study of the interior of the tomb was to define the number of stone layers of the structure, and also evaluate their state and condition.

The two main issues concerned the unknown inner stones arrangement and the circular shape of the burial chamber: the methodology for the radar data acquisition involved the use of a laser scan in order to define accurately each radar line, covering all the internal surface of the tomb. Then, radar data processing was developed by converting cartesian coordinates into polar coordinates.


Eventually, the study of the tumulus outside the tomb, allowed to find out the exact position of the keystone, and pointed out the presence of areas were the radar signal was highly attenuated. This is probably due to the presence of an high salinity in the subsoil, and it is an important information to preserve the tomb with further maintenance, keeping intact its great historical heritage.



GPR: MALÅ Ground Penetrating Radar with a 500-MHz antenna.

Main reference:


For more information please take contact with Mr Klisthenis Dimitriadis. (


The Cathedral of Santa Maria, Palma de Mallorca, Spain


The Cathedral of Santa Maria of Palma is a Gothic Roman Catholic cathedral located in Majorca, Spain, built in the XIV Century by James I of Aragon on the site of a Moorish-era mosque.

This church is characterized by its slim octagonal limestone ashlars columns, where the three pairs near the altar are older and thinner.


Due to its historical importance and to the complex structure of the church, maintenance requires detailed care.

To achieve results as reliable as possible, several techniques were adopted, comparing the outcomes of seismic and electromagnetic methods, of which GPR is commonly used.

In particular, the inner structure of the columns and walls was examined to detect damaged zones and possible infiltrations: radar data was filtered in order to enhance anomalies and minimize the noise.


An interface between the medium and a crack was identifiable by a steep increase (or decrease) of the velocity of propagation of the electromagnetic wave, due to the different electromagnetic characteristics of the mediums.

A transformation of the regular Cartesian radar-grams into polar coordinates allowed to visualize the real shape of the anomalies.


GPR: Ground Penetrating Radar with a 900-MHz and 1.5-GHz antenna.

Main reference:


For more information please take contact with Dr Vega Perez-Gracia. (





Lubiáns Bridge, Galicia, Spain


Since the Middle Ages, masonry arch bridges were built all over Europe. Their origin is to find in the ancient Roman culture, that through colonialism brought this great constructions in many of the european countries. This is the main reason why these very first examples of bridges are nowadays not only a historical heritage, but a proper cultural value.

To preserve their historical character, Non-destructive testing techniques were employed to evaluate their condition.


The GPR is one of the most recommended, since it is a relatively quick technique that provides an overall internal image of the structure and supposes an equitable compromise between good resolution and high penetration depth.


In this case of study, the GPR was used for detecting inner structural characteristics such as the presence of internal voids, hidden arches, former shapes, restorations and moisture content of the Lubiáns Bridge.

Lubiáns Bridge was built in Galicia, Spain, in the XV century: since then, it has suffered several reconstructions with different materials.


This made the study with the GPR particularly complicated because of multiple reflections and diffraction events, that is why the inspection was supported by the FDTD method. By comparing data field obtained from the GPR to a synthetic one, classifying all the layers and aggregates that compose the bridge, it was possible to create a model of its inner structure.


Two GPR profile lines were acquired through the downstream and upstream extremes of the pathway in longitudinal direction. For trace-interval distance calculation, the GPR antenna was assembled on a survey cart with encoder.


In the radar-grams obtained, it was possible to discriminate between the reflection patterns due to the interface bridge-air and the ones that revealed the presence of different filling materials.


GPR: Ground Penetrating Radar RAMACCU-II with a 500 MHz antenna .

Main reference:


For more information please take contact with Dr Mercedes Solla. (





Railways in Portugal


With the increase of loads and travel speed, the railway monitoring has assumed a main role for what concerns safety in travelling.

In particular, is important to detect any track defects due to wear and tear.


The maintenance actions currently used are based on the geometric level parameters assessed without giving information about the defects causes: that is why GPR is used.

In fact, Ground Penetrating Radar is a quick and non-invasive technique to evaluate infrastructure condition.


In railway monitoring, GPR can be used to measure the layers thicknesses and to detect structural changes that point out the presence of ballast pockets, poor drainage and others kind of deteriorations that generally cause the vertical deviations in track geometry.


These results have encouraged the development of new GPR systems working at higher frequencies to obtain outcomes that are more accurate, new software and new algorithms for calculation of material’s properties.


GPR: GPR GSSI and IDS with 5 antennas from 400 to 1800 MHz.

Main reference:


For more information please take contact with Dr Simona Fontul. (





Fatigue carrousel of IFSTTAR, France


Nowadays, radar systems are commonly used for pavement surveys in non-destructive testing, due to the high data acquisition rate and global monitoring through quasi-continuous measurements that they can achieve.

Non-destructive tests allow to survey pavements avoiding road’s disruption and, above all, in a safer way.


Usual radar systems use 2 or 3 antennas at different central frequency to investigate at different depth.


They are able to collect data at traffic speed, providing B-scan records of the roadways pavement by acquiring measurements along a longitudinal profile.

In this way, it is possible to detect layer interfaces, evaluate layer thickness and identify possible defects in the structure, but this possibility is limited by the footprint of the radar waves.


This is why some system including many antennas to provide a 3D mapping was proposed and presented at IFSTTAR Nantes.

This systems are based on a step frequency Ground-penetrating-radar composed by several antennas that allow to acquire 21 B-scans.


To compare the performances of this new system with the pulsed one, a survey was made on the pavement fatigue carrousel of IFSSTTAR (Nantes, French). It is a large scale circular outdoor test facility, unique in Europe by its size (120 m long) and loading capabilities (maximum loading speed of 100 km/h equating to a loading rate of one million cycles per month).

In particular, 25 m long pavement section has been dedicated to study detection of defect, intentionally incorporated, at interface between the two layers that compose the pavement.


The 3D approach presenting timeslices at various depths enabled to recognize particular embedded anomalies revealing their shape or alignments. It provided a better lateral resolution which is greatly increased using high density of parallel profiles.

From a road engineer point of view, these results allow to detect accurately even the smallest defects of a roadway pavement, giving the chance to determine their origin (fatigue due to traffic or other type of damage).



GPR: Step frequency radar with 11 transmitters and 11 receivers. The central frequency is about

1.5 GHz.

Main reference:


For more information please take contact with Dr X. Derobert. (





Radiant heating floors in residences


Nowadays, radiant heating floors are replacing other heating technologies thanks to their main feature of being low-temperature. This allows reaching the requested thermal comfort reducing energy consumption, with all the consequent advantages.


However, radiant heating floors need maintenance, and the best way to evaluate their condition is monitoring them with non-destructive techniques, saving time and money. GPR is a good tool to complement the information that can be collected using infrared thermography.


Actually, infrared allows analysing heat transfer phenomenon, obtaining data on the condition of the pipelines, but says nothing about geometry and configuration. Then, if survey concerns highly reflective materials, it is quite impossible to distinguish heat produced by a pipe and heat reflected by objects that surround it.


GPR is based on the dielectric response due to the shape of the objects and especially to their material: therefore, the large dielectric contrast between the installation and the surrounding backfill guarantees a high resolution in radar-grams.


To test the synergy of these two non-destructive techniques, two rooms of different use and floor coating have been studied: a living room with low-reflectivity ceramic tiles as floor coating and a bedroom with parquet flooring in brick pattern.


Three-dimensional GPR methodologies were performed in order to obtain an optimal visualization and improve the interpretation of the acquired data. This methodology consisted in the acquisition of equidistant parallel 2D-lines in the Y-direction, at regular intervals of 5 cm.


GPR: MALÅ ProEx system with a 2.3 GHz antenna.

Main ref.:


For more information please take contact with Dr Mercedes Solla. (



Geotechnics and Geology


Adria-Dinarides, Slovenia


As a result of the tectonostratigraphic evolution and geological movements of the Adria-Dinarides thrust zone, the Karstic thrust edge was formed and today represents a considerable obstacle for the construction of the new railway route Divača–Koper.


To obtain an accurate map of the complex 3D structure inside the subsoil, a geophysical method such as GPR was needed. In fact, it was not possible to study the structure by digging boreholes: it would be too expensive and time consuming.


To investigate the shallow features and detecting low-angle inclined thrusts, 13 GPR profiles were recorded with a GPR system with 50 MHz antenna.


The profiles were positioned across selected existing boreholes: the outcomes were compared with ones obtained by the geological mapping.

The use of the GPR not only provided precise information on the geometry of the thrust-fault of Socerb, but also was very useful for locating cavities, both air- and sediment-filled.


GPR: GPR with 50 MHz antenna.

Main reference:


For more information please take contact with Prof. Andrej Gosar. (


Subsoil of Barcelona City, Spain


The shallowest part of Barcelona City’s coastal geology is formed by Quaternary sediments and is crossed by paleochannels and streams.


Mapping the subsoil allows to improve the knowledge of all the geological layers under the city structures and constructions.


GPR is widely used in this kind of study, because of its capability to get quick information without digging expensive and invasive boreholes: once one has obtained an assessment, is possible to detect zones that need a further investigation.


To detect paleochannels and subterranean and seasonal streams, coherent energy reflected by targets is used to identify any change of material in subsoil. Actually, properties of material influence the velocity of propagation of the electromagnetic wave, giving the chance to discriminate geometries.


The main issue is provided by the heterogeneous composition of the subsoil, full of grains and small discontinuities. Any of this, produce many reflected waves that make difficult the interpretation of radar images.


However, it is precisely this feature that allows detecting paleochannels and streams: several tests establish that their presence cause a steep increase in the signal noise, due to the heterogeneity.


GPR: GPR with 25 MHz antenna.

Main reference:


For more information please take contact with Dr S. Santos-Assunçao.(




Subsoil of a petrol station


Even if, nowadays, the analysis of soil pollution using non-invasive techniques is still largely experimental, it is possible to obtain accurate results combining a multi-receiver electromagnetic induction (EMI) and GPR system.


EMI provides information about the apparent electrical conductivity and magnetic susceptibility, while GPR is useful to locate soil contamination by detecting changes in relative dielectric permittivity.


Actually, petroleum hydrocarbons initially reduce dielectric permittivity and electrical conductivity of water that is poured in the pore spaces. Then an anomaly rise of the conductivity occurs, due to the biodegradation effects.


Investigating a 0.1 ha parking area close to a former petrol station, both the EMI and GPR measurements have indicated the presence of mineral oil in the upper few meters of the soil, as earlier invasive methods have pointed out.


GPR: 3d-Radar GeoScope (model GS3F) GPR system with V1213 array antenna from 50 to 1500 MHz.

Main reference:


For more information please take contact with Prof. Marc Van Meirvenne. (


Subsoil of a gas plant site, Belgium


Replacing boreholes drilling with a non-invasive and non-destructive method in order to investigate soil pollution is one of the main challenges for industrial sites.

These zones usually exhibit a large heterogeneity, due to the presence of demolition debris, industrial waste and buried structures such as foundations.


The application of only one sensor is generally insufficient, because its outcome rely on several soil properties, but a synergy use of different investigation methods, such as GPR and EMI, allows discriminating between all contributing factors.


The subsoil of a gas plant site located in one of the seaport areas of Belgium was surveyed with this multi-sensor approach. An area of 3400 m2 was investigated.


The GPR, assembled in a mobile set-up with real-time georeferencing to obtain a high-resolution coverage area, pointed out the presence of different materials in the subsoil, detecting contrasts in dielectric permittivity.


GPR: GeoScope GS3F GPR system with 50 to 3000 MHz.

Main reference:

For more information please take contact with Prof. Marc Van Meirvenne. (



Natural landscapes


Tree species from Louvain-La-Neuve and Brussels, Belgium


For what concerns road safety, is important to evaluate the health of trees, to prevent their collapse and avoid accidents.

It is also important to characterize the properties of tree wood in order to use them in construction.

Obviously, for such an application is required a non-destructive observation, that is why GPR is a promising technology.


Tree trunk internal structure is divided into three main parts: heartwood, sapwood and bark. This heterogeneous composition, in addition to the circular shape, complicates the investigation. Furthermore, the properties of wood rely not only on the botanical species of the tree, but also on environmental conditions (water content, density and temperature of wood) and on the presence of insects, fungi or birds.


The study was split in three parts: firstly, the optimal functionality of the GPR was investigated using the numerical simulation tool GprMax2d.

Then, laboratory tests were made using a model of a decayed tree trunk, built with plastic filled by sand.

Eventually, measurements on a real tree trunks occurred. Several tree species in Louvain-la-Neuve and Brussels, in Belgium, were taken into account.


GPR: GPR GSSI with 900 MHz antenna.

For more information please take contact with Prof. Sebastien Lambot. (


Petrified Forest of Evros, Greece


The Petrified Forest of Evros, situated in the northern part of Greece, is the oldest of the country: approximately 35 million years old.


Its exposure to the erosion by weather conditions makes it necessary to undertake maintenance projects: this survey was conducted as part of a more extensive framework oriented to protect this natural monument, considering it both as a natural ecosystem and part of cultural heritage.

That is why Non-destructive investigation methods have been chosen.


Using the GPR, it was possible to locate buried fossilized tree trunks constructing two and three-dimensional subsurface geophysical images of the surveyed area.


A complete analysis of the subsoil was obtained comparing the GPR’s outcomes with the ones given by another Non-Destructive Technique: Electrical Resistivity Tomography.


Main reference:


For more information please take contact with Dr Nectaria Diamanti.


Timanfaya National Park, Lanzarote Island, Spain


During a volcanic eruption, if flows are very fluid, lava continues to circulate beneath the already cooled crust, forming lava tubes. These caves are usually unstable, because of the lava roof that could collapse, provoking geotechnical problems regarding loads on foundations.


To detect hidden lava tubes, a study in Timanfaya National Park was made, a volcanic area situated in the Southwest of Lanzarote Island, in Spain.

It covers an area of 51 km2, and houses more than 30 volcanic cones, formed in different phases of basaltic type eruptions.

The capability of GPR to discriminate geometries was supported by a numerical FDTD modelling.


In fact, a heterogeneous medium with irregular geometry presents complex reflection patterns that are difficult to interpret; but, comparing FDTD and GPR outcomes, it was possible to obtain accurate results.


The method was firstly calibrated over lava flows located at the Calderas Quemadas zone, where the cavities can be visually identified. Then, the same method was applied in the Chinero zone.


GPR: RAMAC/GPR system Mala Geoscience with a 200 MHz antenna.


For more information please take contact with Dr Mercedes Solla. (





Sense-City, Marne-La-Vallèe, France


To satisfy a large number of utility services it is necessary to build all the required infrastructures, and usually they are located within 1.5 m of the ground surface.

This is why the subsurface is full of pipelines for providing fiber optics, telecommunication lines, electrical cables and other numerous services.


Monitoring the underground is important to get a complete inspection of the spatial organization of the subsoil in order to update urban cadastral databases and have awareness of land resources when planning for new networks.

Such an assessment is also useful to evaluate the status of buried pipes.


The GPR is a valid candidate to perform this kind of assessment: a non-destructive technique allows to get a quick response, saving time and money.

Then, it is able to detect the presence of metallic or dielectric buried objects providing high-resolution data. However, a wide variation of ground conditions (particularly water content) may affect measures.


To study and improve the use of GPR in this kind of assessment, a test was managed in the Sense-City, a mini- city demonstrator in Marne-La-Vallèe, France.

It consists of a 250 m2 real size model of a city district focused on smart houses, roads and city furniture. It includes two distinct areas dedicated to the validation of utility mapping tools, one with buried pipes, and the other with buried blades; the objects have relative small lateral dimension (less than 15 cm).


Through an inspection managed with three different GPR systems, a survey of the underground was made by acquiring radar-grams that contained pipe signatures.

Use different frequencies allowed to identify firstly the multilayer structure of the underground, then the presence of every buried pipe.


GPR: For time domain GSSI SIR 3000, UtilityScan DF. For frequency domain SFCW with a pair of bowtie slot antennas, both operating from 300 to 1500 GHz.

Main reference:


For more information please take contact with Dr Xavier Derobert. (





For information concerning the COST Action TU1208, please take contact with the Chair of the Action, Dr. Lara Pajewski - This website is supported by COST, European COoperation in Science and Technology - COST is supported by the EU RTD Framework Programme Horizon2020.

TU1208 Members are deeply grateful to COST for funding and supporting the COST Action TU1208.