Made possible by the collection of on-board tailpipe emissions data, this research identifies roa... more Made possible by the collection of on-board tailpipe emissions data, this research identifies road and driver factors that are associated with a relatively understudied tailpipe pollutant from lightduty vehicles: ultrafine particle number emissions. High emission events (HEE) of ultrafine particle number (PN) emissions occurred most frequently at locations with steep upgrades or locations that required moderate to rapid accelerations (\u3e3 mph/s). The analysis revealed that less than 2% of the time driving was responsible for almost a third of all ultrafine particles emitted along the designated 17-mile test route for a sample of 22 drivers. Variables identified in a generalized linear model as significant to PN emissions include measures of engine speed (RPM), driver behavior (speed and acceleration rates), and road geometry (grade). These factors account for approximately 61% of the variability measured. Few modal emissions models estimate PN emissions; however, this research has...
Introduction: Predicting crash counts by severity plays a dominant role in identifying roadway si... more Introduction: Predicting crash counts by severity plays a dominant role in identifying roadway sites that experience overrepresented crashes, or an increase in the potential for crashes with higher severity levels. Valid and reliable methodologies for predicting highway accidents by severity are necessary in assessing contributing factors to severe highway crashes, and assisting the practitioners in allocating safety improvement resources. Methods: This paper uses urban & suburban intersection data in Connecticut, along with two sophisticated modeling approaches, i.e. a Multivariate Poisson-Lognormal (MVPLN) model and a Joint Negative Binomial-Generalized Ordered Probit Fractional Split (NB-GOPFS) model to assess the methodological rationality and accuracy by accommodating for the unobserved factors in predicting crash counts by severity level. Furthermore, crash prediction models based on vehicle damage level are estimated using the same two methodologies to supplement the injury severity in estimating crashes by severity when the sample mean of severe injury crashes (e.g. fatal crashes) is very low. Results: The model estimation results highlight the presence of correlations of crash counts among severity levels, as well as the crash counts in total and crash proportions by different severity levels. A comparison of results indicates that injury severity and vehicle damage are highly consistent. Conclusions: Crash severity counts are significantly correlated and should be accommodated in crash prediction models. Practical Application: The findings of this research could help select sound and reliable methodologies for predicting highway accidents by injury severity. When crash data samples have challenges associated with the low observed sampling rates for severe injury crashes, this research also confirmed that vehicle damage can be appropriate as an alternative to injury severity in crash prediction by severity.
Made possible by the collection of on-board tailpipe emissions data, this research identifies roa... more Made possible by the collection of on-board tailpipe emissions data, this research identifies road and driver factors that are associated with a relatively understudied tailpipe pollutant from light-duty vehicles: ultrafine particle number emissions. High emission events (HEE) of ultrafine particle number (PN) emissions occurred most frequently at locations with steep upgrades or locations that required moderate to rapid accelerations (>3 mph/s). The analysis revealed that less than 2% of the time driving was responsible for almost a third of all ultrafine particles emitted along the designated 17-mile test route for a sample of 22 drivers. Variables identified in a generalized linear model as significant to PN emissions include measures of engine speed (RPM), driver behavior (speed and acceleration rates), and road geometry (grade). These factors account for approximately 61% of the variability measured. Few modal emissions models estimate PN emissions; however, this research ha...
Traveler route choice behavior is the cornerstone of numerous advanced traffic management technol... more Traveler route choice behavior is the cornerstone of numerous advanced traffic management technologies. Yet, we lack data to describe the route decision making undertaken by drivers. While in-vehicle Global Positioning System (GPS) receivers seem to be a logical means to collect travel data, very few GPS travel route datasets have been collected and analyzed to understand driver behavior. This paper summarizes the findings of several recent field-based research projects which address the methodological issues in use of GPS for travel route data: spatial data typology and conversion; map-matching GPS data to underlying road networks; obtaining comprehensive link travel time data; and missing data issues due to urban canyons. The extent of complications in collecting and using these route data is significant, but this paper demonstrates that the methods to overcome these problems are feasible. Most importantly, these efforts illustrate that datasets of travel routes be collected along...
Transportation Research Record: Journal of the Transportation Research Board
Adverse weather conditions are one of the primary causes of motor vehicle crashes. To identify th... more Adverse weather conditions are one of the primary causes of motor vehicle crashes. To identify the factors contributing to crashes during adverse weather conditions and recommend cost-effective countermeasures, it is necessary to develop reliable crash prediction models to estimate weather-related crash frequencies. To account for the variations in crash count among different adverse weather conditions, crash types, and crash severities for both rain- and snow-related crashes, crash data on freeways was collected from the State of Connecticut, and crash prediction models were developed to estimate crash counts by crash type and severity for each weather condition. To account for the potential correlations among crash type and severity counts due to the common unobserved factors, integrated nested Laplace approximation (INLA) multivariate Poisson lognormal (MVPLN) models were developed to estimate weather-related crashes counts by crash type and severity simultaneously (four MVPLN mo...
16. Abstract This report focuses on analysis of statistical association between wet pavement fric... more 16. Abstract This report focuses on analysis of statistical association between wet pavement friction and crash incidence, controlling for pertinent road characteristics such as shoulder width, speed limit, curves, intersections, driveways and area type. The objective of this ...
Transportation Research Record Journal of the Transportation Research Board, 2004
... Aultman-Hall, Jackson, Dougan, and Choi 125 weak. ... Use of the standard deviation of rut-ti... more ... Aultman-Hall, Jackson, Dougan, and Choi 125 weak. ... Use of the standard deviation of rut-ting in the proximate sections of the roadway shows promise as a predictor variable to connect IRI and pavement distress variables. ACKNOWLEDGMENTS ...
Transportation Research Record: Journal of the Transportation Research Board, 2010
New models and data are needed in microscopic traffic simulation tools to allow effective use wit... more New models and data are needed in microscopic traffic simulation tools to allow effective use with newer modal tailpipe emissions models. Traffic simulation models offer the ability to simulate large, second-by-second vehicle operation data sets as input for emissions models. However, more data are needed to improve simulation of second-by-second vehicle speed. This research analyzes and models the vehicle dynamics of unconstrained drivers in real-world driving situations based on road geometry. Vehicle dynamics data were collected by using an instrumented vehicle driven by 22 volunteers over a 17-mi predetermined test route. The objective of this research was to analyze and model the nonrandom speed variations in unconstrained lead drivers. The results of this study suggest that horizontal and vertical curvatures have a significant impact on the second-by-second operation of an unconstrained lead vehicle. Furthermore, these nonrandom changes in speed are important considerations si...
An 18-month study of the organization and structure of the Connecticut Transportation Institute (... more An 18-month study of the organization and structure of the Connecticut Transportation Institute (CTI) was performed. The structure and operations of other transportation research centers were studied. A Peer Exchange, held July 30-August 1, 2003, provided the core recommendations to organize, market and expand CTI research. A brochure describing CTI and a display booth were designed and obtained. A strategic plan was developed that includes specific one-and five-year actions. A series of performance measures developed in this project were recommended to the CTI director. The performance measures tabulated thus far indicate that overall research activities have increased between July 2002-June2003 and July2003-June2004. This project provided the impetus and tools needed to start this growth.
... Aultman-Hall, Jackson, Dougan, and Choi 125 weak. ... Use of the standard deviation of rut-ti... more ... Aultman-Hall, Jackson, Dougan, and Choi 125 weak. ... Use of the standard deviation of rut-ting in the proximate sections of the roadway shows promise as a predictor variable to connect IRI and pavement distress variables. ACKNOWLEDGMENTS ...
An instrumented minivan on a 30-mile (48 km) test route was used to measure second-by-second vehi... more An instrumented minivan on a 30-mile (48 km) test route was used to measure second-by-second vehicle operating characteristics as well as tailpipe particulate and gas emissions. Our research objectives are: 1) to quantify the variability of gas and particulate emissions between 12 drivers; and 2) to measure the relative emission level on freeways, signalized arterials, rural two-lane arterials and local roads. The results reaffirm that individual drivers significantly affect emissions levels. All emissions concentrations were also systematically related to road type. Furthermore, drivers could be grouped by emissions level, but these groupings differ by pollutant and by road type. More data are needed to elucidate driver-road type interactions and to characterize the regional driver pool for more robust microscale emissions models. The relative importance of driver type compared to other factors known to affect emissions needs to be quantified. Finally, two key issues were identified as affecting the accuracy of instantaneous emissions measurements: instrument response time effects on data alignment and accurately quantifying the full range of on-road exhaust flow rates.
Transportation Research Record: Journal of the Transportation Research Board, 2009
This research aims to provide new understanding on time-resolved particle number emissions from c... more This research aims to provide new understanding on time-resolved particle number emissions from conventional diesel (CD) transit buses and hybrid diesel-electric (HDE) buses. The first objective of this research was to investigate the differences in vehicle operation between the hybrid and conventional buses on a second-by-second basis. The second objective was to investigate particle number emissions to determine if there are significant differences between the two vehicle types.
... Operating Mode for Emissions Research Eric Jackson, Lisa Aultman-Hall, Britt A. Holmén, and J... more ... Operating Mode for Emissions Research Eric Jackson, Lisa Aultman-Hall, Britt A. Holmén, and Jianhe Du ... Recent studies have also compared GPS data collection of velocity and acceleration with those collected using the chase car technique. ...
Transportation Research Record: Journal of the Transportation Research Board, 2010
... the speed profiles generated by traffic sim-ulation may be adequate for modal binning if ... ... more ... the speed profiles generated by traffic sim-ulation may be adequate for modal binning if ... Overall this suggests that variations in second-by-second lead vehicle operation will increase second ... This analysis indicates that grade can affect the second-by-second speed of a vehicle. ...
Made possible by the collection of on-board tailpipe emissions data, this research identifies roa... more Made possible by the collection of on-board tailpipe emissions data, this research identifies road and driver factors that are associated with a relatively understudied tailpipe pollutant from lightduty vehicles: ultrafine particle number emissions. High emission events (HEE) of ultrafine particle number (PN) emissions occurred most frequently at locations with steep upgrades or locations that required moderate to rapid accelerations (\u3e3 mph/s). The analysis revealed that less than 2% of the time driving was responsible for almost a third of all ultrafine particles emitted along the designated 17-mile test route for a sample of 22 drivers. Variables identified in a generalized linear model as significant to PN emissions include measures of engine speed (RPM), driver behavior (speed and acceleration rates), and road geometry (grade). These factors account for approximately 61% of the variability measured. Few modal emissions models estimate PN emissions; however, this research has...
Introduction: Predicting crash counts by severity plays a dominant role in identifying roadway si... more Introduction: Predicting crash counts by severity plays a dominant role in identifying roadway sites that experience overrepresented crashes, or an increase in the potential for crashes with higher severity levels. Valid and reliable methodologies for predicting highway accidents by severity are necessary in assessing contributing factors to severe highway crashes, and assisting the practitioners in allocating safety improvement resources. Methods: This paper uses urban & suburban intersection data in Connecticut, along with two sophisticated modeling approaches, i.e. a Multivariate Poisson-Lognormal (MVPLN) model and a Joint Negative Binomial-Generalized Ordered Probit Fractional Split (NB-GOPFS) model to assess the methodological rationality and accuracy by accommodating for the unobserved factors in predicting crash counts by severity level. Furthermore, crash prediction models based on vehicle damage level are estimated using the same two methodologies to supplement the injury severity in estimating crashes by severity when the sample mean of severe injury crashes (e.g. fatal crashes) is very low. Results: The model estimation results highlight the presence of correlations of crash counts among severity levels, as well as the crash counts in total and crash proportions by different severity levels. A comparison of results indicates that injury severity and vehicle damage are highly consistent. Conclusions: Crash severity counts are significantly correlated and should be accommodated in crash prediction models. Practical Application: The findings of this research could help select sound and reliable methodologies for predicting highway accidents by injury severity. When crash data samples have challenges associated with the low observed sampling rates for severe injury crashes, this research also confirmed that vehicle damage can be appropriate as an alternative to injury severity in crash prediction by severity.
Made possible by the collection of on-board tailpipe emissions data, this research identifies roa... more Made possible by the collection of on-board tailpipe emissions data, this research identifies road and driver factors that are associated with a relatively understudied tailpipe pollutant from light-duty vehicles: ultrafine particle number emissions. High emission events (HEE) of ultrafine particle number (PN) emissions occurred most frequently at locations with steep upgrades or locations that required moderate to rapid accelerations (>3 mph/s). The analysis revealed that less than 2% of the time driving was responsible for almost a third of all ultrafine particles emitted along the designated 17-mile test route for a sample of 22 drivers. Variables identified in a generalized linear model as significant to PN emissions include measures of engine speed (RPM), driver behavior (speed and acceleration rates), and road geometry (grade). These factors account for approximately 61% of the variability measured. Few modal emissions models estimate PN emissions; however, this research ha...
Traveler route choice behavior is the cornerstone of numerous advanced traffic management technol... more Traveler route choice behavior is the cornerstone of numerous advanced traffic management technologies. Yet, we lack data to describe the route decision making undertaken by drivers. While in-vehicle Global Positioning System (GPS) receivers seem to be a logical means to collect travel data, very few GPS travel route datasets have been collected and analyzed to understand driver behavior. This paper summarizes the findings of several recent field-based research projects which address the methodological issues in use of GPS for travel route data: spatial data typology and conversion; map-matching GPS data to underlying road networks; obtaining comprehensive link travel time data; and missing data issues due to urban canyons. The extent of complications in collecting and using these route data is significant, but this paper demonstrates that the methods to overcome these problems are feasible. Most importantly, these efforts illustrate that datasets of travel routes be collected along...
Transportation Research Record: Journal of the Transportation Research Board
Adverse weather conditions are one of the primary causes of motor vehicle crashes. To identify th... more Adverse weather conditions are one of the primary causes of motor vehicle crashes. To identify the factors contributing to crashes during adverse weather conditions and recommend cost-effective countermeasures, it is necessary to develop reliable crash prediction models to estimate weather-related crash frequencies. To account for the variations in crash count among different adverse weather conditions, crash types, and crash severities for both rain- and snow-related crashes, crash data on freeways was collected from the State of Connecticut, and crash prediction models were developed to estimate crash counts by crash type and severity for each weather condition. To account for the potential correlations among crash type and severity counts due to the common unobserved factors, integrated nested Laplace approximation (INLA) multivariate Poisson lognormal (MVPLN) models were developed to estimate weather-related crashes counts by crash type and severity simultaneously (four MVPLN mo...
16. Abstract This report focuses on analysis of statistical association between wet pavement fric... more 16. Abstract This report focuses on analysis of statistical association between wet pavement friction and crash incidence, controlling for pertinent road characteristics such as shoulder width, speed limit, curves, intersections, driveways and area type. The objective of this ...
Transportation Research Record Journal of the Transportation Research Board, 2004
... Aultman-Hall, Jackson, Dougan, and Choi 125 weak. ... Use of the standard deviation of rut-ti... more ... Aultman-Hall, Jackson, Dougan, and Choi 125 weak. ... Use of the standard deviation of rut-ting in the proximate sections of the roadway shows promise as a predictor variable to connect IRI and pavement distress variables. ACKNOWLEDGMENTS ...
Transportation Research Record: Journal of the Transportation Research Board, 2010
New models and data are needed in microscopic traffic simulation tools to allow effective use wit... more New models and data are needed in microscopic traffic simulation tools to allow effective use with newer modal tailpipe emissions models. Traffic simulation models offer the ability to simulate large, second-by-second vehicle operation data sets as input for emissions models. However, more data are needed to improve simulation of second-by-second vehicle speed. This research analyzes and models the vehicle dynamics of unconstrained drivers in real-world driving situations based on road geometry. Vehicle dynamics data were collected by using an instrumented vehicle driven by 22 volunteers over a 17-mi predetermined test route. The objective of this research was to analyze and model the nonrandom speed variations in unconstrained lead drivers. The results of this study suggest that horizontal and vertical curvatures have a significant impact on the second-by-second operation of an unconstrained lead vehicle. Furthermore, these nonrandom changes in speed are important considerations si...
An 18-month study of the organization and structure of the Connecticut Transportation Institute (... more An 18-month study of the organization and structure of the Connecticut Transportation Institute (CTI) was performed. The structure and operations of other transportation research centers were studied. A Peer Exchange, held July 30-August 1, 2003, provided the core recommendations to organize, market and expand CTI research. A brochure describing CTI and a display booth were designed and obtained. A strategic plan was developed that includes specific one-and five-year actions. A series of performance measures developed in this project were recommended to the CTI director. The performance measures tabulated thus far indicate that overall research activities have increased between July 2002-June2003 and July2003-June2004. This project provided the impetus and tools needed to start this growth.
... Aultman-Hall, Jackson, Dougan, and Choi 125 weak. ... Use of the standard deviation of rut-ti... more ... Aultman-Hall, Jackson, Dougan, and Choi 125 weak. ... Use of the standard deviation of rut-ting in the proximate sections of the roadway shows promise as a predictor variable to connect IRI and pavement distress variables. ACKNOWLEDGMENTS ...
An instrumented minivan on a 30-mile (48 km) test route was used to measure second-by-second vehi... more An instrumented minivan on a 30-mile (48 km) test route was used to measure second-by-second vehicle operating characteristics as well as tailpipe particulate and gas emissions. Our research objectives are: 1) to quantify the variability of gas and particulate emissions between 12 drivers; and 2) to measure the relative emission level on freeways, signalized arterials, rural two-lane arterials and local roads. The results reaffirm that individual drivers significantly affect emissions levels. All emissions concentrations were also systematically related to road type. Furthermore, drivers could be grouped by emissions level, but these groupings differ by pollutant and by road type. More data are needed to elucidate driver-road type interactions and to characterize the regional driver pool for more robust microscale emissions models. The relative importance of driver type compared to other factors known to affect emissions needs to be quantified. Finally, two key issues were identified as affecting the accuracy of instantaneous emissions measurements: instrument response time effects on data alignment and accurately quantifying the full range of on-road exhaust flow rates.
Transportation Research Record: Journal of the Transportation Research Board, 2009
This research aims to provide new understanding on time-resolved particle number emissions from c... more This research aims to provide new understanding on time-resolved particle number emissions from conventional diesel (CD) transit buses and hybrid diesel-electric (HDE) buses. The first objective of this research was to investigate the differences in vehicle operation between the hybrid and conventional buses on a second-by-second basis. The second objective was to investigate particle number emissions to determine if there are significant differences between the two vehicle types.
... Operating Mode for Emissions Research Eric Jackson, Lisa Aultman-Hall, Britt A. Holmén, and J... more ... Operating Mode for Emissions Research Eric Jackson, Lisa Aultman-Hall, Britt A. Holmén, and Jianhe Du ... Recent studies have also compared GPS data collection of velocity and acceleration with those collected using the chase car technique. ...
Transportation Research Record: Journal of the Transportation Research Board, 2010
... the speed profiles generated by traffic sim-ulation may be adequate for modal binning if ... ... more ... the speed profiles generated by traffic sim-ulation may be adequate for modal binning if ... Overall this suggests that variations in second-by-second lead vehicle operation will increase second ... This analysis indicates that grade can affect the second-by-second speed of a vehicle. ...
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Papers by Eric Jackson