Traffic accidents are very serious problems for human life and the environment. In road safety, i... more Traffic accidents are very serious problems for human life and the environment. In road safety, it is crucial to identify the high risk locations to apply proper counter measures. This paper aims at introducing outcomes of a pilot project whose main goal is to develop a GIS based crash analysis system integrated with the quantitative methods for identification of high risk locations on road networks in Turkey. In this concept, traditional hotspot detection methods used in Turkey(crash frequency, rate, and severity) are compared with the spatial statistical methods including Moran‟s I, GetisOrd G and planar and network kernel density estimation in terms of their sensitivity to spatial characteristics of crash clusters. Many countries use traditional hotspot detection approaches such as crash frequency, crash rate, and crash severity as well as Turkey. In this project, we aimed at obtaining a model including different hotspot identification methods for the safety program of Turkey. In order to obtain the model, many hotspot detection methods will be used and compare stage by stage. In the first stage, the seven methods mentioned above are used and examined. Although some of these methods are compared in couple, there is no study using all these methods together extensively in the literature. Methods validated with a different spatial vantage points. Repetitiveness of hotspots in a seven years period are used to compare the methods. Meanwhile advantages and disadvantages of the methods according to location of hotspots are examined additionally. Results show that using planar KDE with Gi in the junction locations and using planar KDE with Moran‟s I in the straight road locations could improve the model while determining hotspots
In recent years, the usage of the Precise Point Positioning (PPP) has increased due to its ease
o... more In recent years, the usage of the Precise Point Positioning (PPP) has increased due to its ease of use, providing high accuracy as well as reducing the field operational costs by using only a single GNSS receiver. Moreover, it does not require any additional reference station data or CORS-like network data. It is a positioning technique that has been extensively investigated and used in a variety of applications, mainly for conventional surveying applications and time-transfer, ionospheric and tropospheric characterization. In GNSS positioning, limited satellite visibility in obstructed areas and poor satellite geometry adversely affect the accuracy of results. With the revitalization of the GLONASS system reaching to full global coverage, PPP studies have focused on combined GPS and GLONASS solutions. The goal of this study is to investigate the usability of PPP technique in urban areas with GPS-only and GPS + GLONASS data by the use of online-PPP services for sub-decimeter surveying applications. For this purpose, test measurements were conducted in Çorum province of Turkey. Collected data were evaluated with two commonly used PPP services, namely CSRS-PPP operated by the Geodetic Survey Division of Natural Resources Canada (NRCan) and magicGNSS/PPP developed by Spanish GMV Aerospace and Defense Co. Results obtained from this study revealed that for some cases, the use of GLONASS with GPS raises the number of satellites used in the solution twice as much as compared to GPS-only. However, unless satellites geometry gets better, the use of GLONASS has no significant role in strengthening the accuracy of results. The results indicate that an increase in the number of satellites is vital especially in urban areas where minimum number of satellites for a solution may not be obtained. Also, it was observed that when the sufficient numbers of GPS satellites with good geometry are available combining GPS together with GLONASS may not bring any significant contribution to the solution.
Precise Point Positioning (PPP) attracts more users for many surveying and mapping applications t... more Precise Point Positioning (PPP) attracts more users for many surveying and mapping applications that provide users an alternative solution different from the differential GNSS positioning methods. Although PPP was initially developed for the GPS observations, with the advent of the precise products for GLONASS constellation, PPP technique has started to use additional GLONASS observations. Other additional GNSS system’s data will allow positions to be determined more accurately even in high-rise cities where buildings obscure signals from satellites. The aim of this study is to compare GPS-only and combined GPS+GLONASS PPP results in urban area using online-PPP service, i.e. CSRS-PPP. The overall results show that, in general, additional GNSS constellation allows for more reliable and precise surveying, especially in urban areas, mountains, areas with heavy tree cover, ravines, open pit mines and usually when the satellite signals are blocked or degraded by various obstacles.
After the 1999 Izmit and Düzce earthquakes, the earth science studies increase on the NAF to bett... more After the 1999 Izmit and Düzce earthquakes, the earth science studies increase on the NAF to better understand mechanism and to monitor the motion of it. Monitoring such motion can be achieved by the instrumental tools or techniques like GPS, InSAR, LIDAR, creep meter, etc. The GPS observations showed that while the NW-SE trending section of the NAF between Karlıova and Vezirköprü has nearly strike slip mechanism, the NE-SW trending section of the NAF between Vezirköprü and Bolu has transpressive character. While the fault-parallel velocities have been estimated from just a few GPS vectors available in the region, little is known about the fault-perpendicular component of the regional velocity. The rate of conversion and how it varies along strike are not known due to the sparsely distributed GPS benchmarks in the region. At the same time, the aseismic fault creep determined using InSAR has needed to proof and improve by other techniques and tools. For this propose the new project has been started to determine quantitatively the rate of convergence and its variation along segment of the NAF between Bolu and Çorum. In this study, we focus on the Bolu-Çorum segment of the NAFZ using GPS technique. The main aim of this study is determination of creep rate with geodetic measurements and combination of the data obtained from seismology, geodesy and geophysics to understand fault mechanism. Therefore, in this paper we discuss tectonic phenomena on the central part of the NAFZ and present the first results of the project.
After the completion of the GLONASS (GLObalnaya NAvigatsionnaya Sputnikovaya Sistema or GLObal NA... more After the completion of the GLONASS (GLObalnaya NAvigatsionnaya Sputnikovaya Sistema or GLObal NAvigation Satellite System) which was developed by Russian Federation and making it service as second running system all over the world after GPS, satellite based geodetic studies have been focused on integration of GPS and GLONASS systems. It is possible to determine the position and/or increase the accuracy and reliability by receiving more data from the satellites especially for the forested lands, urban canyons, open mine areas and valleys etc. which have inadequate number of satellites or weak signals. Nowadays, development in satellite technology and dazzling progress in data processing and analysis allows to point positioning within cm to dm level with only a single GNSS receiver. It is possible to make positioning by using the method called as Precise Point Positioning (PPP) in static or kinematic mode using precise orbit and clock data without being in need of any data other than collected with a single receiver. Until recently, PPP-derived coordinates were obtained by only scientific GNSS processing software but now it is possible to obtain a result with the software that universities or institutes coded or commercial software. However, all these programs require GNSS knowledge and generally requires licensing fee. Recently, many on-line PPP processing services which eliminates the disadvantages and have practical usage have been started to be used. One of these services, CSRS-PPP(Canadian Spatial Reference System-Precise Point Positioning) attracts attention with its accuracy and ease of use. In this study, static measurements were performed with the receivers which can collect data from GPS and GLONASS satellite systems at the geodetic points from intense residential areas in Çorum city region, mostly around the city center. Collected data was evaluated separately by GPS and by GPS+GLONASS integrated systems with CSRS-PPP service operated by Canada. The PPP-derived coordinates were compared with the ones obtained by differential method (accepted as accurate coordinates). In order to investigate the effect of Rapid and Final precise products (with have different latency) on the result, the data was uploaded to the system after finishing the measurements and again just after several weeks, and the results were compared. In this study, the test procedure and obtained results are discussed.
Traffic accidents are very serious problems for human life and the environment. In road safety, i... more Traffic accidents are very serious problems for human life and the environment. In road safety, it is crucial to identify the high risk locations to apply proper counter measures. This paper aims at introducing outcomes of a pilot project whose main goal is to develop a GIS based crash analysis system integrated with the quantitative methods for identification of high risk locations on road networks in Turkey. In this concept, traditional hotspot detection methods used in Turkey(crash frequency, rate, and severity) are compared with the spatial statistical methods including Moran‟s I, GetisOrd G and planar and network kernel density estimation in terms of their sensitivity to spatial characteristics of crash clusters. Many countries use traditional hotspot detection approaches such as crash frequency, crash rate, and crash severity as well as Turkey. In this project, we aimed at obtaining a model including different hotspot identification methods for the safety program of Turkey. In order to obtain the model, many hotspot detection methods will be used and compare stage by stage. In the first stage, the seven methods mentioned above are used and examined. Although some of these methods are compared in couple, there is no study using all these methods together extensively in the literature. Methods validated with a different spatial vantage points. Repetitiveness of hotspots in a seven years period are used to compare the methods. Meanwhile advantages and disadvantages of the methods according to location of hotspots are examined additionally. Results show that using planar KDE with Gi in the junction locations and using planar KDE with Moran‟s I in the straight road locations could improve the model while determining hotspots
In recent years, the usage of the Precise Point Positioning (PPP) has increased due to its ease
o... more In recent years, the usage of the Precise Point Positioning (PPP) has increased due to its ease of use, providing high accuracy as well as reducing the field operational costs by using only a single GNSS receiver. Moreover, it does not require any additional reference station data or CORS-like network data. It is a positioning technique that has been extensively investigated and used in a variety of applications, mainly for conventional surveying applications and time-transfer, ionospheric and tropospheric characterization. In GNSS positioning, limited satellite visibility in obstructed areas and poor satellite geometry adversely affect the accuracy of results. With the revitalization of the GLONASS system reaching to full global coverage, PPP studies have focused on combined GPS and GLONASS solutions. The goal of this study is to investigate the usability of PPP technique in urban areas with GPS-only and GPS + GLONASS data by the use of online-PPP services for sub-decimeter surveying applications. For this purpose, test measurements were conducted in Çorum province of Turkey. Collected data were evaluated with two commonly used PPP services, namely CSRS-PPP operated by the Geodetic Survey Division of Natural Resources Canada (NRCan) and magicGNSS/PPP developed by Spanish GMV Aerospace and Defense Co. Results obtained from this study revealed that for some cases, the use of GLONASS with GPS raises the number of satellites used in the solution twice as much as compared to GPS-only. However, unless satellites geometry gets better, the use of GLONASS has no significant role in strengthening the accuracy of results. The results indicate that an increase in the number of satellites is vital especially in urban areas where minimum number of satellites for a solution may not be obtained. Also, it was observed that when the sufficient numbers of GPS satellites with good geometry are available combining GPS together with GLONASS may not bring any significant contribution to the solution.
Precise Point Positioning (PPP) attracts more users for many surveying and mapping applications t... more Precise Point Positioning (PPP) attracts more users for many surveying and mapping applications that provide users an alternative solution different from the differential GNSS positioning methods. Although PPP was initially developed for the GPS observations, with the advent of the precise products for GLONASS constellation, PPP technique has started to use additional GLONASS observations. Other additional GNSS system’s data will allow positions to be determined more accurately even in high-rise cities where buildings obscure signals from satellites. The aim of this study is to compare GPS-only and combined GPS+GLONASS PPP results in urban area using online-PPP service, i.e. CSRS-PPP. The overall results show that, in general, additional GNSS constellation allows for more reliable and precise surveying, especially in urban areas, mountains, areas with heavy tree cover, ravines, open pit mines and usually when the satellite signals are blocked or degraded by various obstacles.
After the 1999 Izmit and Düzce earthquakes, the earth science studies increase on the NAF to bett... more After the 1999 Izmit and Düzce earthquakes, the earth science studies increase on the NAF to better understand mechanism and to monitor the motion of it. Monitoring such motion can be achieved by the instrumental tools or techniques like GPS, InSAR, LIDAR, creep meter, etc. The GPS observations showed that while the NW-SE trending section of the NAF between Karlıova and Vezirköprü has nearly strike slip mechanism, the NE-SW trending section of the NAF between Vezirköprü and Bolu has transpressive character. While the fault-parallel velocities have been estimated from just a few GPS vectors available in the region, little is known about the fault-perpendicular component of the regional velocity. The rate of conversion and how it varies along strike are not known due to the sparsely distributed GPS benchmarks in the region. At the same time, the aseismic fault creep determined using InSAR has needed to proof and improve by other techniques and tools. For this propose the new project has been started to determine quantitatively the rate of convergence and its variation along segment of the NAF between Bolu and Çorum. In this study, we focus on the Bolu-Çorum segment of the NAFZ using GPS technique. The main aim of this study is determination of creep rate with geodetic measurements and combination of the data obtained from seismology, geodesy and geophysics to understand fault mechanism. Therefore, in this paper we discuss tectonic phenomena on the central part of the NAFZ and present the first results of the project.
After the completion of the GLONASS (GLObalnaya NAvigatsionnaya Sputnikovaya Sistema or GLObal NA... more After the completion of the GLONASS (GLObalnaya NAvigatsionnaya Sputnikovaya Sistema or GLObal NAvigation Satellite System) which was developed by Russian Federation and making it service as second running system all over the world after GPS, satellite based geodetic studies have been focused on integration of GPS and GLONASS systems. It is possible to determine the position and/or increase the accuracy and reliability by receiving more data from the satellites especially for the forested lands, urban canyons, open mine areas and valleys etc. which have inadequate number of satellites or weak signals. Nowadays, development in satellite technology and dazzling progress in data processing and analysis allows to point positioning within cm to dm level with only a single GNSS receiver. It is possible to make positioning by using the method called as Precise Point Positioning (PPP) in static or kinematic mode using precise orbit and clock data without being in need of any data other than collected with a single receiver. Until recently, PPP-derived coordinates were obtained by only scientific GNSS processing software but now it is possible to obtain a result with the software that universities or institutes coded or commercial software. However, all these programs require GNSS knowledge and generally requires licensing fee. Recently, many on-line PPP processing services which eliminates the disadvantages and have practical usage have been started to be used. One of these services, CSRS-PPP(Canadian Spatial Reference System-Precise Point Positioning) attracts attention with its accuracy and ease of use. In this study, static measurements were performed with the receivers which can collect data from GPS and GLONASS satellite systems at the geodetic points from intense residential areas in Çorum city region, mostly around the city center. Collected data was evaluated separately by GPS and by GPS+GLONASS integrated systems with CSRS-PPP service operated by Canada. The PPP-derived coordinates were compared with the ones obtained by differential method (accepted as accurate coordinates). In order to investigate the effect of Rapid and Final precise products (with have different latency) on the result, the data was uploaded to the system after finishing the measurements and again just after several weeks, and the results were compared. In this study, the test procedure and obtained results are discussed.
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of use, providing high accuracy as well as reducing the field operational costs by using only
a single GNSS receiver. Moreover, it does not require any additional reference station data
or CORS-like network data. It is a positioning technique that has been extensively investigated
and used in a variety of applications, mainly for conventional surveying applications
and time-transfer, ionospheric and tropospheric characterization. In GNSS positioning, limited
satellite visibility in obstructed areas and poor satellite geometry adversely affect the
accuracy of results. With the revitalization of the GLONASS system reaching to full global
coverage, PPP studies have focused on combined GPS and GLONASS solutions. The goal of
this study is to investigate the usability of PPP technique in urban areas with GPS-only and
GPS + GLONASS data by the use of online-PPP services for sub-decimeter surveying applications.
For this purpose, test measurements were conducted in Çorum province of Turkey.
Collected data were evaluated with two commonly used PPP services, namely CSRS-PPP
operated by the Geodetic Survey Division of Natural Resources Canada (NRCan) and
magicGNSS/PPP developed by Spanish GMV Aerospace and Defense Co. Results obtained
from this study revealed that for some cases, the use of GLONASS with GPS raises the number
of satellites used in the solution twice as much as compared to GPS-only. However,
unless satellites geometry gets better, the use of GLONASS has no significant role in
strengthening the accuracy of results. The results indicate that an increase in the number
of satellites is vital especially in urban areas where minimum number of satellites for a
solution may not be obtained. Also, it was observed that when the sufficient numbers of
GPS satellites with good geometry are available combining GPS together with GLONASS
may not bring any significant contribution to the solution.
of use, providing high accuracy as well as reducing the field operational costs by using only
a single GNSS receiver. Moreover, it does not require any additional reference station data
or CORS-like network data. It is a positioning technique that has been extensively investigated
and used in a variety of applications, mainly for conventional surveying applications
and time-transfer, ionospheric and tropospheric characterization. In GNSS positioning, limited
satellite visibility in obstructed areas and poor satellite geometry adversely affect the
accuracy of results. With the revitalization of the GLONASS system reaching to full global
coverage, PPP studies have focused on combined GPS and GLONASS solutions. The goal of
this study is to investigate the usability of PPP technique in urban areas with GPS-only and
GPS + GLONASS data by the use of online-PPP services for sub-decimeter surveying applications.
For this purpose, test measurements were conducted in Çorum province of Turkey.
Collected data were evaluated with two commonly used PPP services, namely CSRS-PPP
operated by the Geodetic Survey Division of Natural Resources Canada (NRCan) and
magicGNSS/PPP developed by Spanish GMV Aerospace and Defense Co. Results obtained
from this study revealed that for some cases, the use of GLONASS with GPS raises the number
of satellites used in the solution twice as much as compared to GPS-only. However,
unless satellites geometry gets better, the use of GLONASS has no significant role in
strengthening the accuracy of results. The results indicate that an increase in the number
of satellites is vital especially in urban areas where minimum number of satellites for a
solution may not be obtained. Also, it was observed that when the sufficient numbers of
GPS satellites with good geometry are available combining GPS together with GLONASS
may not bring any significant contribution to the solution.