International Conference on Transportation and Development, 2023
The applications of geospatial technologies and positioning data embrace every sphere of modern-d... more The applications of geospatial technologies and positioning data embrace every sphere of modern-day science and industry where geographical positioning matters. Among all other fields, geospatial technology plays a remarkable role in the transportation sector and has the potential to play an even more critical role in future autonomous transportation systems. In this regard, the GNSS-real-time network (GNSS-RTN) technology is promising in meeting the needs of automation in most advanced transportation applications. The GNSS-RTN is a satellite-based positioning system that uses a network of reference stations to provide centimeter-level accuracy in positioning data in real time. The technical aspect and working technology of GNSS-RTN are widely studied; however, only limited research has been conducted on the various GNSS-RTN business models currently in use nationally and internationally. Therefore, this study aims at assessing the various GNSS-RTN business models currently used in practice as well as those that are deemed potentially viable but have not yet moved to practice. Eight different business models were cataloged and used in the current assessment. All business models were assessed using three criteria: state control, sustainability, and state/agency costs. The findings of this research are important in helping state agencies make informed decisions as they build, expand, or manage their own GNSS-RTN systems.
Understanding the influence of roundabouts on operating speeds along connecting roadway segments ... more Understanding the influence of roundabouts on operating speeds along connecting roadway segments is important for developing facility-level operational analyses along highway corridors and in modeling speed deceleration and acceleration in microscopic simulation. This study aims to investigate the influence area of roundabouts along rural and suburban corridors that would assist in determining the quality of traffic operations along highways involving roundabouts. The study used speed data collected via multiple test car runs along three roundabout corridors: two in the state of Washington and one in Colorado. Drivers' speed profiles while driving through the roundabout corridors were established and analyzed. Furthermore, statistical analyses were conducted to model the upstream and downstream influence areas at the three study sites and in testing the effect of traffic volume and posted speed limit on the influence area. Study results suggest that the downstream influence area is significantly longer than the upstream influence area. Traffic flow level was found to have no significant effect on the roundabout influence area; however, the posted speed limit was found to significantly affect the upstream and downstream roundabout influence areas. The study results provided important information about the spatial extent of the operational effect of roundabouts on connecting approaches. However, these results are specifically derived using rural and suburban corridors and therefore may not be applicable to lower-speed urban environments.
The Global Navigation Satellite System—Real-Time Network (GNSS-RTN) is a satellite-based position... more The Global Navigation Satellite System—Real-Time Network (GNSS-RTN) is a satellite-based positioning system using a network of ground receivers (also called continuously operating reference stations (CORSs)) and a central processing center that provides highly accurate location services to the users in real-time over a broader geographic region. Such systems can provide geospatial location data with centimeter-level accuracy anywhere within the network. Geospatial location services are not only used in measuring ground distances and mapping topography; they have also become vital in many other fields such as aerospace, aviation, natural disaster management, and agriculture, to name but a few. The innovative and multi-disciplinary applications of geospatial data drive technological advancement towards precise and accurate location services available in real-time. Although GNSS-RTN technology is currently utilized in a few industries such as precision farming, the construction industry, and land surveying, the implications of precise real-time location services would be far-reaching and more critical to many advanced transportation applications. The GNSS-RTN technology is promising in meeting the needs of automation in most advanced transportation applications. This article presents an overview of the GNSS-RTN technology, its current applications in transportation-related fields, and a perspective on the future use of this technology in advanced transportation applications.
Low-volume roads (LVRs) are an integral part of the rural transportation network providing access... more Low-volume roads (LVRs) are an integral part of the rural transportation network providing access to remote rural areas and facilitating the movement of goods from farms to markets. These roads pose unique challenges for highway agencies including those related to safety management on the highway network. Specifically, traditional network screening methods using crash history can be effective in screening rural highways with higher traffic volumes and more frequent crashes. However, these traditional methods are often ineffective in screening LVR networks due to low traffic volumes and the sporadic nature of crash occurrence. Further, many of the LVRs are owned and operated by local agencies that may lack access to detailed crash, traffic and roadway data and the technical expertise within their staff. Therefore, there is a need for more efficient and practical network screening approaches to facilitate safety management programs on these roads. This study proposes one such approach which utilizes a heuristic scoring scheme in assessing the level of risk/safety for the purpose of network screening. The proposed scheme is developed based on the principles of US Highway Safety Manual (HSM) analysis procedures for rural highways and the fundamentals in safety science. The primary application of the proposed scheme is for ranking sites in network screening applications or for comparing multiple improvement alternatives at a specific site. The proposed approach does not require access to detailed databases, technical expertise, or exact information, making it an invaluable tool for small agencies and local governments (e.g. counties, townships, tribal governments, etc.).
The applications of geospatial technologies and positioning data embrace every sphere of modern-d... more The applications of geospatial technologies and positioning data embrace every sphere of modern-day science and industry. With technological advancement, the demands for highly accurate positioning services in real-time led to the development of the Global Navigation Satellite System-Real-Time Network (GNSS-RTN). While there is numerous published information on the technical aspects of the GNSS-RTN technology, information on the best practices or guidelines in building, operating, and managing the GNSS-RTN networks is lacking in practice. To better understand the current practice in establishing and operating the GNSS-RTN systems, an online questionnaire survey was sent to the GNSS-RTN system owners/operators across the U.S. Additionally, a thorough review of available literature on business models and interviews with representatives of two major manufacturers/vendors of GNSS-RTN products and services were conducted. Study results revealed a great deal of inconsistency in current practices among states in the way the GNSS-RTN systems are built, operated, and managed. Aspects of the diversity in state practices involved the business models for the GNSS-RTN systems besides the technical attributes of the network and system products. The information gathered in this study is important in helping state agencies make informed decisions as they build, expand or manage their own GNSS-RTN systems.
Understanding the influence of intersections on operating conditions along connecting roadway seg... more Understanding the influence of intersections on operating conditions along connecting roadway segments is important for the analysis of highway facilities and corridors. This study aims at assessing the influence area at signalized and stop-control intersections along rural corridors. The study used speed as a performance measure in examining the spatial extent of operational effects at intersections. High-fidelity connected vehicle (CV) trajectory data, collected at 11 different sites in Florida, was used in this study. The CV trajectory data consists of individual waypoints that included timestamps and location coordinates along with other attributes. Drivers' speed profiles while driving through the intersection were established and analyzed to determine the length of upstream and downstream influence areas. Quantile regression models were developed to estimate the 50th, 70th, and 85th percentiles of upstream and downstream influence areas separately for signalized and stopcontrol intersections. Study results indicate that the upstream influence area is longer for a signalized intersection than for a stop-control intersection for comparable segment running speeds. Further, the downstream influence area is significantly longer than the upstream influence area at signalized intersections, and this was consistent at all study sites. Traffic flow level did not have a significant effect on the upstream or downstream influence area; however, midblock running speed, percent heavy vehicles, and facility type (multilane versus two-lane) were found to significantly affect the upstream and downstream influence areas at signalized intersections.
International Conference on Transportation and Development 2022, 2022
Geospatial location service is not only used in measuring ground distances and mapping topography... more Geospatial location service is not only used in measuring ground distances and mapping topography, but has also become vital in many other fields such as aerospace, aviation, natural disaster management, and agriculture, to name but a few. The innovative and multidisciplinary applications of geospatial data drive technological advancement toward precise and accurate location services available in real-time. Although the RTN technology is currently utilized in a few industries such as precision farming, construction industry, and land survey, the implications of precise real-time location services would be far-reaching and critical to many advanced transportation applications. The GNSS real-time network (RTN) technology, introduced in the mid-1990s, is promising in meeting the needs of automation in most of the advanced transportation applications. This article presents an overview of the GNSS-RTN technology, its current applications in transportation-related fields, and a perspective on the future use of this technology in advanced transportation applications.
ASCE International Conference on Transportation and Development 2019, 2019
Self-reporting is a valuable tool in transportation research practices especially in driver's non... more Self-reporting is a valuable tool in transportation research practices especially in driver's non-compliance behavior on-and off-road. Self-reporting often serves as a proxy and provides access to data that may be difficult to obtain by other means. Whereas assessment and validation of such subjective observations is another challenge to decipher, objective measures of drivers' behavior (i.e. speed behavior) could be useful to assess the correlation with self-reported data. To appraise the reliability of drivers' self-reported data, this study was conducted to analyze drivers' perceptions of their driving speed and compare it with the actual operating speed. Data was collected for the Seward Highway in Alaska; a two-lane highway that connects Anchorage with Seward. The actual operating speed data and the self-reported data were collected at passing lanes sites where a strategy of differential speed limits was recently implemented. Similarly, to model drivers' self-reported attitude data, a seemingly unrelated regression (SUR) was used to account for contemporaneous correlation of error terms and the endogenous behavior of variables in the system of equations. Mean free-flow speeds were compared to the expected means of the drivers' self-reported speeds using one-way ANOVA. In terms of operating speeds, the results suggested that the actual speeds of vehicles in the passing lanes were higher than the current posted speed limits (PSLs). The results of the statistical analysis indicated a significant discrepancy between the actual operating speeds and the drivers' selfreported speeds. The findings of this study could have significant implications on the implementation of PSLs, and regarding the perception of drivers about their own speeding behavior on two-lane highways and the passing lanes, which may be addressed to improve safety. The drivers may be educated about PSLs, to improve traffic safety and operations and strategies be devised to better reduce the above-stated discrepancy.
International Conference on Transportation and Development, 2023
The applications of geospatial technologies and positioning data embrace every sphere of modern-d... more The applications of geospatial technologies and positioning data embrace every sphere of modern-day science and industry where geographical positioning matters. Among all other fields, geospatial technology plays a remarkable role in the transportation sector and has the potential to play an even more critical role in future autonomous transportation systems. In this regard, the GNSS-real-time network (GNSS-RTN) technology is promising in meeting the needs of automation in most advanced transportation applications. The GNSS-RTN is a satellite-based positioning system that uses a network of reference stations to provide centimeter-level accuracy in positioning data in real time. The technical aspect and working technology of GNSS-RTN are widely studied; however, only limited research has been conducted on the various GNSS-RTN business models currently in use nationally and internationally. Therefore, this study aims at assessing the various GNSS-RTN business models currently used in practice as well as those that are deemed potentially viable but have not yet moved to practice. Eight different business models were cataloged and used in the current assessment. All business models were assessed using three criteria: state control, sustainability, and state/agency costs. The findings of this research are important in helping state agencies make informed decisions as they build, expand, or manage their own GNSS-RTN systems.
Understanding the influence of roundabouts on operating speeds along connecting roadway segments ... more Understanding the influence of roundabouts on operating speeds along connecting roadway segments is important for developing facility-level operational analyses along highway corridors and in modeling speed deceleration and acceleration in microscopic simulation. This study aims to investigate the influence area of roundabouts along rural and suburban corridors that would assist in determining the quality of traffic operations along highways involving roundabouts. The study used speed data collected via multiple test car runs along three roundabout corridors: two in the state of Washington and one in Colorado. Drivers' speed profiles while driving through the roundabout corridors were established and analyzed. Furthermore, statistical analyses were conducted to model the upstream and downstream influence areas at the three study sites and in testing the effect of traffic volume and posted speed limit on the influence area. Study results suggest that the downstream influence area is significantly longer than the upstream influence area. Traffic flow level was found to have no significant effect on the roundabout influence area; however, the posted speed limit was found to significantly affect the upstream and downstream roundabout influence areas. The study results provided important information about the spatial extent of the operational effect of roundabouts on connecting approaches. However, these results are specifically derived using rural and suburban corridors and therefore may not be applicable to lower-speed urban environments.
The Global Navigation Satellite System—Real-Time Network (GNSS-RTN) is a satellite-based position... more The Global Navigation Satellite System—Real-Time Network (GNSS-RTN) is a satellite-based positioning system using a network of ground receivers (also called continuously operating reference stations (CORSs)) and a central processing center that provides highly accurate location services to the users in real-time over a broader geographic region. Such systems can provide geospatial location data with centimeter-level accuracy anywhere within the network. Geospatial location services are not only used in measuring ground distances and mapping topography; they have also become vital in many other fields such as aerospace, aviation, natural disaster management, and agriculture, to name but a few. The innovative and multi-disciplinary applications of geospatial data drive technological advancement towards precise and accurate location services available in real-time. Although GNSS-RTN technology is currently utilized in a few industries such as precision farming, the construction industry, and land surveying, the implications of precise real-time location services would be far-reaching and more critical to many advanced transportation applications. The GNSS-RTN technology is promising in meeting the needs of automation in most advanced transportation applications. This article presents an overview of the GNSS-RTN technology, its current applications in transportation-related fields, and a perspective on the future use of this technology in advanced transportation applications.
Low-volume roads (LVRs) are an integral part of the rural transportation network providing access... more Low-volume roads (LVRs) are an integral part of the rural transportation network providing access to remote rural areas and facilitating the movement of goods from farms to markets. These roads pose unique challenges for highway agencies including those related to safety management on the highway network. Specifically, traditional network screening methods using crash history can be effective in screening rural highways with higher traffic volumes and more frequent crashes. However, these traditional methods are often ineffective in screening LVR networks due to low traffic volumes and the sporadic nature of crash occurrence. Further, many of the LVRs are owned and operated by local agencies that may lack access to detailed crash, traffic and roadway data and the technical expertise within their staff. Therefore, there is a need for more efficient and practical network screening approaches to facilitate safety management programs on these roads. This study proposes one such approach which utilizes a heuristic scoring scheme in assessing the level of risk/safety for the purpose of network screening. The proposed scheme is developed based on the principles of US Highway Safety Manual (HSM) analysis procedures for rural highways and the fundamentals in safety science. The primary application of the proposed scheme is for ranking sites in network screening applications or for comparing multiple improvement alternatives at a specific site. The proposed approach does not require access to detailed databases, technical expertise, or exact information, making it an invaluable tool for small agencies and local governments (e.g. counties, townships, tribal governments, etc.).
The applications of geospatial technologies and positioning data embrace every sphere of modern-d... more The applications of geospatial technologies and positioning data embrace every sphere of modern-day science and industry. With technological advancement, the demands for highly accurate positioning services in real-time led to the development of the Global Navigation Satellite System-Real-Time Network (GNSS-RTN). While there is numerous published information on the technical aspects of the GNSS-RTN technology, information on the best practices or guidelines in building, operating, and managing the GNSS-RTN networks is lacking in practice. To better understand the current practice in establishing and operating the GNSS-RTN systems, an online questionnaire survey was sent to the GNSS-RTN system owners/operators across the U.S. Additionally, a thorough review of available literature on business models and interviews with representatives of two major manufacturers/vendors of GNSS-RTN products and services were conducted. Study results revealed a great deal of inconsistency in current practices among states in the way the GNSS-RTN systems are built, operated, and managed. Aspects of the diversity in state practices involved the business models for the GNSS-RTN systems besides the technical attributes of the network and system products. The information gathered in this study is important in helping state agencies make informed decisions as they build, expand or manage their own GNSS-RTN systems.
Understanding the influence of intersections on operating conditions along connecting roadway seg... more Understanding the influence of intersections on operating conditions along connecting roadway segments is important for the analysis of highway facilities and corridors. This study aims at assessing the influence area at signalized and stop-control intersections along rural corridors. The study used speed as a performance measure in examining the spatial extent of operational effects at intersections. High-fidelity connected vehicle (CV) trajectory data, collected at 11 different sites in Florida, was used in this study. The CV trajectory data consists of individual waypoints that included timestamps and location coordinates along with other attributes. Drivers' speed profiles while driving through the intersection were established and analyzed to determine the length of upstream and downstream influence areas. Quantile regression models were developed to estimate the 50th, 70th, and 85th percentiles of upstream and downstream influence areas separately for signalized and stopcontrol intersections. Study results indicate that the upstream influence area is longer for a signalized intersection than for a stop-control intersection for comparable segment running speeds. Further, the downstream influence area is significantly longer than the upstream influence area at signalized intersections, and this was consistent at all study sites. Traffic flow level did not have a significant effect on the upstream or downstream influence area; however, midblock running speed, percent heavy vehicles, and facility type (multilane versus two-lane) were found to significantly affect the upstream and downstream influence areas at signalized intersections.
International Conference on Transportation and Development 2022, 2022
Geospatial location service is not only used in measuring ground distances and mapping topography... more Geospatial location service is not only used in measuring ground distances and mapping topography, but has also become vital in many other fields such as aerospace, aviation, natural disaster management, and agriculture, to name but a few. The innovative and multidisciplinary applications of geospatial data drive technological advancement toward precise and accurate location services available in real-time. Although the RTN technology is currently utilized in a few industries such as precision farming, construction industry, and land survey, the implications of precise real-time location services would be far-reaching and critical to many advanced transportation applications. The GNSS real-time network (RTN) technology, introduced in the mid-1990s, is promising in meeting the needs of automation in most of the advanced transportation applications. This article presents an overview of the GNSS-RTN technology, its current applications in transportation-related fields, and a perspective on the future use of this technology in advanced transportation applications.
ASCE International Conference on Transportation and Development 2019, 2019
Self-reporting is a valuable tool in transportation research practices especially in driver's non... more Self-reporting is a valuable tool in transportation research practices especially in driver's non-compliance behavior on-and off-road. Self-reporting often serves as a proxy and provides access to data that may be difficult to obtain by other means. Whereas assessment and validation of such subjective observations is another challenge to decipher, objective measures of drivers' behavior (i.e. speed behavior) could be useful to assess the correlation with self-reported data. To appraise the reliability of drivers' self-reported data, this study was conducted to analyze drivers' perceptions of their driving speed and compare it with the actual operating speed. Data was collected for the Seward Highway in Alaska; a two-lane highway that connects Anchorage with Seward. The actual operating speed data and the self-reported data were collected at passing lanes sites where a strategy of differential speed limits was recently implemented. Similarly, to model drivers' self-reported attitude data, a seemingly unrelated regression (SUR) was used to account for contemporaneous correlation of error terms and the endogenous behavior of variables in the system of equations. Mean free-flow speeds were compared to the expected means of the drivers' self-reported speeds using one-way ANOVA. In terms of operating speeds, the results suggested that the actual speeds of vehicles in the passing lanes were higher than the current posted speed limits (PSLs). The results of the statistical analysis indicated a significant discrepancy between the actual operating speeds and the drivers' selfreported speeds. The findings of this study could have significant implications on the implementation of PSLs, and regarding the perception of drivers about their own speeding behavior on two-lane highways and the passing lanes, which may be addressed to improve safety. The drivers may be educated about PSLs, to improve traffic safety and operations and strategies be devised to better reduce the above-stated discrepancy.
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