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Elsa Tedla

University of Alabama - Tuscaloosa, Alabama Transportation Institute, Research Engineer

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I am a Research Engineer at The University of Alabama. My research interests include traffic operations, traffic simulation and modelling, traffic safety, intelligent transportation systems (ITS), and transportation data and planning.
Supervisors: Steven Jones

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Papers by Elsa Tedla

Exploring the Determinants of School Bus Crash Severity

Safety

Although the school bus is considered a safe form of transportation, school bus crashes are a maj... more Although the school bus is considered a safe form of transportation, school bus crashes are a major safety concern. School bus crashes are a result of driver error of either the at-fault school bus or another at-fault vehicle (where the school bus is not at fault). To examine the risk factors associated with school bus related crashes and crash outcomes, this study segments and develops two binary logit models for each school bus crash type. A total of 1702 school bus related crashes recorded between 2009 and 2016 were used to estimate the model. According to the model results, sideswipe collisions were less likely to result in injury outcomes for at-fault school buses than rear-end and side-impact collisions. Speeding, driving impaired or under the influence, and negotiating a curve all have significant positive associations with injury outcomes in not-at-fault school bus crashes. This study’s practical implications include enforcing the school bus safe driving guidelines, training...

Analytical and Empirical Evaluation of Freight Priority System in Connected Vehicle Environment

Journal of Transportation Engineering, Part A: Systems

Summary Report: Alabama School Bus Seat Belt Pilot Project

The University of Alabama (UA) conducted a three-year project for the Governor’s Study Group on S... more The University of Alabama (UA) conducted a three-year project for the Governor’s Study Group on School Bus Seat Belts and the Alabama State Department of Education. The project explored the implementation of lap/shoulder belts on newly purchased large school buses. It included topics like the rate of seat belt use, the effects on bus discipline, the attitudes of stakeholders, the loss of capacity attributable to seat belts, the cost effectiveness of the belts, and other pertinent issues. A list of some of the most pertinent study findings follows: • In 2009-10 in Alabama, 7,341 route school buses averaged 51 pupils each and traveled 457,258 miles daily (82.3 million miles annually). • Pupil deaths inside school buses are rare in Alabama. Since 1977, when major advancements were made to school bus safety, there have been only five fatalities for pupils riding inside school buses at the time the crash occurred. • School buses are the safest form of transportation to school. Students a...

Selection of a simulation software to model a small signalized system of a multilane arterial in the southeastern US

É comum em estatística espacial o interesse em testar hipóteses relacionadas à associação espacia... more É comum em estatística espacial o interesse em testar hipóteses relacionadas à associação espacial entre dois padrões espaciais. Muitas vezes, as entidades espaciais que melhor representam os dados são polígonos. Contudo a complexidade e falta de técnicas desenvolvidas neste campo força pesquisadores a simplificarem tais polígonos por pontos, como os seus centróides. Neste trabalho, foram desenvolvidas técnicas para testar hipóteses relacionadas a padrões de polígonos. Estas técnicas tiram vantagem de toda a informação presente nas entidades espaciais de interesse. A metodologia aqui desenvolvida tem como ponto central o toroidal shift. A utilização deste método traz consigo desafios que fizeram com que outros autores o desconsiderassem, mesmo sendo ele uma melhor alternativa de modelo nulo. Também foi realizado um estudo de simulação para comprovar a eficácia da metodlogia desenvolvida e comparar diferentes estatísticas de teste. Por fim, as técnicas foram aplicadas a dados reais referentes a diferentes espécies de gramas curtas no estado do Colorado.

Factors associated with driver injury severity of lane changing crashes involving younger and older drivers

Accident Analysis & Prevention, 2021

Kilogauss-strength magnetic fields are often observed in intergranular lanes at the photosphere i... more Kilogauss-strength magnetic fields are often observed in intergranular lanes at the photosphere in the quiet Sun. Such fields are stronger than the equipartition field B e , corresponding to a magnetic energy density that matches the kinetic energy density of photospheric convection, and comparable with the field B p that exerts a magnetic pressure equal to the ambient gas pressure. We present an idealised numerical model of three-dimensional compressible magnetoconvection at the photosphere, for a range of values of the magnetic Reynolds number. In the absence of a magnetic field, the convection is highly supercritical and is characterised by a pattern of vigorous, timedependent, "granular" motions. When a weak magnetic field is imposed upon the convection, magnetic flux is swept into the convective downflows where it forms localised concentrations. Unless this process is significantly inhibited by magnetic diffusion, the resulting fields are often much greater than B e , and the high magnetic pressure in these flux elements leads to their being partially evacuated. Some of these flux elements contain ultra-intense magnetic fields that are significantly greater than B p. Such fields are contained by a combination of the thermal pressure of the gas and the dynamic pressure of the convective motion, and they are constantly evolving. These ultra-intense fields develop owing to nonlinear interactions between magnetic fields and convection; they cannot be explained in terms of "convective collapse" within a thin flux tube that remains in overall pressure equilibrium with its surroundings.

Role of Passengers in Single-Vehicle Drunk-Driving Crashes: An Injury-Severity Analysis

Safety, 2020

Background: Drunk-driving is a major crash risk factor, and crashes resulting from this risky beh... more Background: Drunk-driving is a major crash risk factor, and crashes resulting from this risky behavior tend to be serious and have significant economic and societal impacts. The presence of passengers and their demographics and activities can influence risky driving behaviors such as drunk-driving. However, passengers could either be an “enabling” factor to take more risks or could be an “inhibiting” factor by ensuring safe driving by a drunk-driver. Objective: This study examines whether the presence of passengers affects the contributing factors of single-vehicle (SV) drunk-driving crashes, by presenting a severity analysis of single- and multi-occupant SV drunk-driving crashes, to identify risk factors that contribute to crash severity outcomes, for the effective implementation of relevant countermeasures. Method: A total of 7407 observations for 2012–2016 from the crash database of the State of Alabama was used for this study. The variables were divided into six classes: tempora...

Feasibility Assessment for Implementing Adaptive Traffic Signal Control

Journal of Transportation Engineering, Part A: Systems, 2019

AbstractAdaptive traffic control systems (ATCS) continuously adapt to changing traffic in order t... more

Analytical Techniques for Evaluating the Implementation of Adaptive Traffic Signal Control Systems

Journal of Transportation Engineering, Part A: Systems, 2017

Troas Bölgesi, İlk Tunç Çağı'ndan itibaren stratejik konumu nedeniyle farklı bölgelerden gelen kü... more Troas Bölgesi, İlk Tunç Çağı'ndan itibaren stratejik konumu nedeniyle farklı bölgelerden gelen kültürlerin göç hareketiyle karşı karşıya kalmıştır, ancak bölgenin siyasi ve kültürel olarak yazılı belgelerle tanımlanması ise Son Tunç Çağı ile olur. Son Tunç Çağı'nda Hitit İmparatorluğu'nun siyasi etkisini Batı Anadolu'ya kadar gösterir. Bu nedenle Son Tunç Çağı'nda (yaklaşık M. Ö. 1400-1200) bölgede Hititçenin bir tür Batı Anadolu'da konuşulan lehçesi olan Luwice konuşulduğu genel olarak kabul edilir. Son Tunç Çağı'nın sonrasında ise Balkan kökenli grupların Troas'a geldikleri gözlemlenmektedir. Bu dönemde Troas'da Balkan ve Anadolu kökenli yerli halkın bir arada yaşadığı kabul edilmektedir. Arkaik Dönem'le başlayan koloni çağında ise, bölgeye gelen Greklerin bir akkültürasyon süreci geçirdiklerini antik kaynaklardan anlaşılabilinmektedir.

Reduction of capacity and projected costs associated with seat belt installation on school buses

Transportation Research Part A: Policy and Practice, 2014

ABSTRACT This study examines the potential effects the installation of seat belts on school buses... more ABSTRACT This study examines the potential effects the installation of seat belts on school buses would have on the fleet capacity in Alabama and the resulting cost implications. The study also documents the myriad research studies and professional opinions offered on the potential safety effects of equipping school buses with safety restraints/seat belts. Four seat configurations for the school buses were analyzed. The first configuration represents the most common current bus seating configuration without seat belts, 3 seats on each side of the aisle and 12 rows (3/3-12). The physical space required for seat belt hardware may result in a loss of a row of seats and may reduce the number of students seated per row. Thus, three more configurations were studied: loss of a row of seats (3/3-11), loss of one seat per row (3/2-12), and loss of both a row of seats and a seat per row (3/2-11). The capacity for each configuration for each bus using current pupil loads was determined. The costs associated with installation of seat belts, and purchase and operation of new buses were obtained. Should school bus seat belts become mandatory in Alabama, the results obtained in this study can be used by any school system to determine the optimum configuration for their pupils, which will identify the number of additional buses that must be purchased by the school system. This study found that many of the buses that would become overloaded due to seat belt installation and the resultant loss of seating will be carrying only a few excess pupils. Transportation supervisors may be able to handle such overloads by transferring these pupils to other buses or by adjusting their bus routes to minimize purchase of new buses. Additional suggestions for handling bus overloads were offered in the body of this report.

Trajectory-Based Signal Control in Mixed Connected Vehicle Environments

Journal of Transportation Engineering, Part A: Systems, 2021

AbstractThe emerging connected vehicle (CV) technology has introduced the opportunity to improve ... more

Seat Belt Use on Alabama School Buses

The Alabama State Department of Education commissioned a study of school bus seat belt use on the... more The Alabama State Department of Education commissioned a study of school bus seat belt use on the basis of 12 buses (less than 1% of the fleet) equipped with seat belts and digital camera systems. The initial year of the study established baseline rates for normal situations. About 64,000 pupil observations were gathered from 11 buses on Tuesday through Thursday afternoon routes and from one control bus on Monday through Friday morning and afternoon routes. Afternoon route seat belt use was estimated to be 65.9% on the basis of 44,000 of the observations made. Given the small sample size, this value should be considered representative of the fleet but not exact. Belt use varied widely from bus to bus (94.5% to 4.8%). The degree of scatter was confirmed by large values of the coefficient of variation. Trends were documented for variation by day of week, morning versus afternoon, time on route, effects of bus aides, and changes in use over the school year. The findings confirmed the o...

Factors associated with driver injury severity of lane changing crashes involving younger and older drivers

Accident Analysis & Prevention

Injury-severity analysis of lane change crashes involving commercial motor vehicles on interstate highways

Journal of Safety Research

Factors associated with driver injury severity of lane changing crashes involving younger and older drivers

by Abhay Lidbe and Elsa Tedla

Accident Analysis & Prevention

Injury-severity analysis of lane change crashes involving commercial motor vehicles on interstate highways

by Abhay Lidbe, Elsa Tedla, and kofi Adanu

Journal of Safety Research

Analytical Techniques for Evaluating the Implementation of Adaptive Traffic Signal Control Systems

by Abhay Lidbe and Elsa Tedla

Journal of Transportation Engineering, Part A: Systems

Adaptive traffic signal control (ATCS) reduces congestion, improves travel time reliability, and ... more Adaptive traffic signal control (ATCS) reduces congestion, improves travel time reliability, and prolongs the effectiveness of traffic signal timing. The objective of this paper is to demonstrate different data sources and analysis techniques to compare the arterial performance for before, during, and after ATCS implementation. This paper presents several analyses using field-collected travel time data and simulation modeling techniques. The paper demonstrates that different sources of travel time data can be used to characterize the corridor performance under ATCS. Although corridor travel time is the traditional way to assess the improvements from the newer technologies, other measures need to be looked at for objective evaluation of the new systems. It is recommended to use multiple evaluation techniques for better decision making as every technique has its own limitations. The methodologies discussed will help transportation engineers, planners, and policymakers to understand what analysis can be conducted at any point of an ATCS deployment to evaluate the system performance. As policies and timings are adjusted, this feedback is an effective way to continuously monitor the ATCS and quantify benefits.

Reduction of capacity and projected costs associated with seat belt installation on school buses

by Steven Jones and Elsa Tedla

This study examines the potential effects the installation of seat belts on school buses would ha... more This study examines the potential effects the installation of seat belts on school buses would have on the fleet capacity in Alabama and the resulting cost implications. The study also documents the myriad research studies and professional opinions offered on the potential safety effects of equipping school buses with safety restraints/seat belts. Four seat configurations for the school buses were analyzed. The first configuration represents the most common current bus seating configuration without seat belts, 3 seats on each side of the aisle and 12 rows (3/3-12). The physical space required for seat belt hardware may result in a loss of a row of seats and may reduce the number of students seated per row. Thus, three more configurations were studied: loss of a row of seats (3/3-11), loss of one seat per row (3/2-12), and loss of both a row of seats and a seat per row (3/2-11). The capacity for each configuration for each bus using current pupil loads was determined. The costs associated with installation of seat belts, and purchase and operation of new buses were obtained. Should school bus seat belts become mandatory in Alabama, the results obtained in this study can be used by any school system to determine the optimum configuration for their pupils, which will identify the number of additional buses that must be purchased by the school system. This study found that many of the buses that would become overloaded due to seat belt installation and the resultant loss of seating will be carrying only a few excess pupils. Transportation supervisors may be able to handle such overloads by transferring these pupils to other buses or by adjusting their bus routes to minimize purchase of new buses. Additional suggestions for handling bus overloads were offered in the body of this report.

Role of Passengers in Single-Vehicle Drunk-Driving Crashes: An Injury-Severity Analysis

by Steven Jones and Elsa Tedla

Safety, 2020

Background: Drunk-driving is a major crash risk factor, and crashes resulting from this risky beh... more Background: Drunk-driving is a major crash risk factor, and crashes resulting from this risky behavior tend to be serious and have significant economic and societal impacts. The presence of passengers and their demographics and activities can influence risky driving behaviors such as drunk-driving. However, passengers could either be an "enabling" factor to take more risks or could be an "inhibiting" factor by ensuring safe driving by a drunk-driver. Objective: This study examines whether the presence of passengers affects the contributing factors of single-vehicle (SV) drunk-driving crashes, by presenting a severity analysis of single-and multi-occupant SV drunk-driving crashes, to identify risk factors that contribute to crash severity outcomes, for the effective implementation of relevant countermeasures. Method: A total of 7407 observations for 2012-2016 from the crash database of the State of Alabama was used for this study. The variables were divided into six classes: temporal, locational, driver, vehicle, roadway, and crash characteristics and injury severities into three: severe, minor, and no injury. Two latent class multinomial logit models-one each for single-and multi-occupant crashes-were developed, to analyze the effects of significant factors on injury severity outcomes using marginal effects. Results: The estimated results show that collision with a ditch, runoff road, intersection, winter season, wet roadway, and interstate decreased the probability of severe injuries in both single-and multi-occupant crashes, whereas rural area, road with downward grade, dark and unlit roadway, unemployed driver, and driver with invalid license increased the likelihood of severe injuries for both single-and multi-occupant crashes. Female drivers were more likely to be severely injured in single-occupant crashes, but less likely in multi-occupant crashes. A significant association was found between severe injuries and weekends, residential areas, and crash location close (<25 mi ≈40.23 km) to the residence of the at-fault driver in multi-occupant crashes. Sport utility vehicles were found to be safer when driving with passengers. Conclusions: The model findings show that, although many correlates are consistent between the single-and multi-occupant SV crashes that are associated with locational, roadway, vehicle, temporal, and driver characteristics, their effect can vary across the single-and multi-occupant driving population. The findings from this study can help in targeting interventions, developing countermeasures, and educating passengers to reduce drunk-driving crashes and consequent injuries. Such integrated efforts combined with engineering and emergency response may contribute in developing a true safe systems approach.

Public transport and health outcomes in rural sub-Saharan Africa – A synthesis of professional opinion

by Steven Jones and Elsa Tedla

Journal of Transportation and Health, 2016

Much of the recent transport focus in rural sub-Saharan Africa (SSA) has been on road building an... more Much of the recent transport focus in rural sub-Saharan Africa (SSA) has been on road building and upgrading as opposed to the provision of public transport. The literature reveals evidence of significant negative public health outcomes associated with crashes and pollution attributable to rural transport. We report the results of a synthesis of professional opinion obtained from in-person interviews and an internet survey on health issues related to the provision of public transport in rural SSA. Field interviews were conducted as semi-structured dialogues with some 40 transportation and public health professionals in the capital cities of Ethiopia, Ghana and Kenya. Additionally, 86 responses to an Internet survey were received from 38 African countries. Poor mechanical conditions of vehicles and risky driving behaviours were reported to be an important source of injury from rural road crashes. The factors contributing to unsafe rural public transport were attributable to economic barriers to proper operation. Although there was some mismatch among the survey and interview results and the literature, public transport was shown to be an important potential source of air pollution exposure. The overwhelming conclusion is the lack of true understanding of the health impacts of rural air pollution in relation to basic needs for provision of safe mobility. The findings reflect the awareness of various professional communities and emphasise the complexity of the relationship between rural public transport and public health. Transport and health relationships in places such as rural sub-Saharan Africa are further complicated by the fact that there is such significant potential for positive health outcomes attributable to transport through enhanced access to healthcare, education, commerce, etc. Systematic epidemiological research is needed to fully understand the trade-offs between rural mobility and its impacts to public health in rural sub-Saharan Africa.

Public transport and health outcomes in rural sub-Saharan Africa – A synthesis of professional opinion

by Elsa Tedla, Steven Jones, and Seth Appiah-Opoku

Journal of Transport & Health, 2016

Much of the recent transport focus in rural sub-Saharan Africa (SSA) has been on road building an... more Much of the recent transport focus in rural sub-Saharan Africa (SSA) has been on road building and upgrading as opposed to the provision of public transport. The literature reveals evidence of significant negative public health outcomes associated with crashes and pollution attributable to rural transport. We report the results of a synthesis of professional opinion obtained from in-person interviews and an internet survey on health issues related to the provision of public transport in rural SSA. Field interviews were conducted as semi-structured dialogues with some 40 transportation and public health professionals in the capital cities of Ethiopia, Ghana and Kenya. Additionally, 86 responses to an Internet survey were received from 38 African countries. Poor mechanical conditions of vehicles and risky driving behaviours were reported to be an important source of injury from rural road crashes. The factors contributing to unsafe rural public transport were attributable to economic barriers to proper operation. Although there was some mismatch among the survey and interview results and the literature, public transport was shown to be an important potential source of air pollution exposure. The overwhelming conclusion is the lack of true understanding of the health impacts of rural air pollution in relation to basic needs for provision of safe mobility. The findings reflect the awareness of various professional communities and emphasise the complexity of the relationship between rural public transport and public health. Transport and health relationships in places such as rural sub-Saharan Africa are further complicated by the fact that there is such significant potential for positive health outcomes attributable to transport through enhanced access to healthcare, education, commerce, etc. Systematic epidemiological research is needed to fully understand the trade-offs between rural mobility and its impacts to public health in rural sub-Saharan Africa.

Exploring the Determinants of School Bus Crash Severity

Safety

Although the school bus is considered a safe form of transportation, school bus crashes are a maj... more Although the school bus is considered a safe form of transportation, school bus crashes are a major safety concern. School bus crashes are a result of driver error of either the at-fault school bus or another at-fault vehicle (where the school bus is not at fault). To examine the risk factors associated with school bus related crashes and crash outcomes, this study segments and develops two binary logit models for each school bus crash type. A total of 1702 school bus related crashes recorded between 2009 and 2016 were used to estimate the model. According to the model results, sideswipe collisions were less likely to result in injury outcomes for at-fault school buses than rear-end and side-impact collisions. Speeding, driving impaired or under the influence, and negotiating a curve all have significant positive associations with injury outcomes in not-at-fault school bus crashes. This study’s practical implications include enforcing the school bus safe driving guidelines, training...

Analytical and Empirical Evaluation of Freight Priority System in Connected Vehicle Environment

Journal of Transportation Engineering, Part A: Systems

Summary Report: Alabama School Bus Seat Belt Pilot Project

The University of Alabama (UA) conducted a three-year project for the Governor’s Study Group on S... more The University of Alabama (UA) conducted a three-year project for the Governor’s Study Group on School Bus Seat Belts and the Alabama State Department of Education. The project explored the implementation of lap/shoulder belts on newly purchased large school buses. It included topics like the rate of seat belt use, the effects on bus discipline, the attitudes of stakeholders, the loss of capacity attributable to seat belts, the cost effectiveness of the belts, and other pertinent issues. A list of some of the most pertinent study findings follows: • In 2009-10 in Alabama, 7,341 route school buses averaged 51 pupils each and traveled 457,258 miles daily (82.3 million miles annually). • Pupil deaths inside school buses are rare in Alabama. Since 1977, when major advancements were made to school bus safety, there have been only five fatalities for pupils riding inside school buses at the time the crash occurred. • School buses are the safest form of transportation to school. Students a...

Selection of a simulation software to model a small signalized system of a multilane arterial in the southeastern US

É comum em estatística espacial o interesse em testar hipóteses relacionadas à associação espacia... more É comum em estatística espacial o interesse em testar hipóteses relacionadas à associação espacial entre dois padrões espaciais. Muitas vezes, as entidades espaciais que melhor representam os dados são polígonos. Contudo a complexidade e falta de técnicas desenvolvidas neste campo força pesquisadores a simplificarem tais polígonos por pontos, como os seus centróides. Neste trabalho, foram desenvolvidas técnicas para testar hipóteses relacionadas a padrões de polígonos. Estas técnicas tiram vantagem de toda a informação presente nas entidades espaciais de interesse. A metodologia aqui desenvolvida tem como ponto central o toroidal shift. A utilização deste método traz consigo desafios que fizeram com que outros autores o desconsiderassem, mesmo sendo ele uma melhor alternativa de modelo nulo. Também foi realizado um estudo de simulação para comprovar a eficácia da metodlogia desenvolvida e comparar diferentes estatísticas de teste. Por fim, as técnicas foram aplicadas a dados reais referentes a diferentes espécies de gramas curtas no estado do Colorado.

Factors associated with driver injury severity of lane changing crashes involving younger and older drivers

Accident Analysis & Prevention, 2021

Kilogauss-strength magnetic fields are often observed in intergranular lanes at the photosphere i... more Kilogauss-strength magnetic fields are often observed in intergranular lanes at the photosphere in the quiet Sun. Such fields are stronger than the equipartition field B e , corresponding to a magnetic energy density that matches the kinetic energy density of photospheric convection, and comparable with the field B p that exerts a magnetic pressure equal to the ambient gas pressure. We present an idealised numerical model of three-dimensional compressible magnetoconvection at the photosphere, for a range of values of the magnetic Reynolds number. In the absence of a magnetic field, the convection is highly supercritical and is characterised by a pattern of vigorous, timedependent, "granular" motions. When a weak magnetic field is imposed upon the convection, magnetic flux is swept into the convective downflows where it forms localised concentrations. Unless this process is significantly inhibited by magnetic diffusion, the resulting fields are often much greater than B e , and the high magnetic pressure in these flux elements leads to their being partially evacuated. Some of these flux elements contain ultra-intense magnetic fields that are significantly greater than B p. Such fields are contained by a combination of the thermal pressure of the gas and the dynamic pressure of the convective motion, and they are constantly evolving. These ultra-intense fields develop owing to nonlinear interactions between magnetic fields and convection; they cannot be explained in terms of "convective collapse" within a thin flux tube that remains in overall pressure equilibrium with its surroundings.

Role of Passengers in Single-Vehicle Drunk-Driving Crashes: An Injury-Severity Analysis

Safety, 2020

Background: Drunk-driving is a major crash risk factor, and crashes resulting from this risky beh... more Background: Drunk-driving is a major crash risk factor, and crashes resulting from this risky behavior tend to be serious and have significant economic and societal impacts. The presence of passengers and their demographics and activities can influence risky driving behaviors such as drunk-driving. However, passengers could either be an “enabling” factor to take more risks or could be an “inhibiting” factor by ensuring safe driving by a drunk-driver. Objective: This study examines whether the presence of passengers affects the contributing factors of single-vehicle (SV) drunk-driving crashes, by presenting a severity analysis of single- and multi-occupant SV drunk-driving crashes, to identify risk factors that contribute to crash severity outcomes, for the effective implementation of relevant countermeasures. Method: A total of 7407 observations for 2012–2016 from the crash database of the State of Alabama was used for this study. The variables were divided into six classes: tempora...

Feasibility Assessment for Implementing Adaptive Traffic Signal Control

Journal of Transportation Engineering, Part A: Systems, 2019

AbstractAdaptive traffic control systems (ATCS) continuously adapt to changing traffic in order t... more

Analytical Techniques for Evaluating the Implementation of Adaptive Traffic Signal Control Systems

Journal of Transportation Engineering, Part A: Systems, 2017

Troas Bölgesi, İlk Tunç Çağı'ndan itibaren stratejik konumu nedeniyle farklı bölgelerden gelen kü... more Troas Bölgesi, İlk Tunç Çağı'ndan itibaren stratejik konumu nedeniyle farklı bölgelerden gelen kültürlerin göç hareketiyle karşı karşıya kalmıştır, ancak bölgenin siyasi ve kültürel olarak yazılı belgelerle tanımlanması ise Son Tunç Çağı ile olur. Son Tunç Çağı'nda Hitit İmparatorluğu'nun siyasi etkisini Batı Anadolu'ya kadar gösterir. Bu nedenle Son Tunç Çağı'nda (yaklaşık M. Ö. 1400-1200) bölgede Hititçenin bir tür Batı Anadolu'da konuşulan lehçesi olan Luwice konuşulduğu genel olarak kabul edilir. Son Tunç Çağı'nın sonrasında ise Balkan kökenli grupların Troas'a geldikleri gözlemlenmektedir. Bu dönemde Troas'da Balkan ve Anadolu kökenli yerli halkın bir arada yaşadığı kabul edilmektedir. Arkaik Dönem'le başlayan koloni çağında ise, bölgeye gelen Greklerin bir akkültürasyon süreci geçirdiklerini antik kaynaklardan anlaşılabilinmektedir.

Reduction of capacity and projected costs associated with seat belt installation on school buses

Transportation Research Part A: Policy and Practice, 2014

ABSTRACT This study examines the potential effects the installation of seat belts on school buses... more ABSTRACT This study examines the potential effects the installation of seat belts on school buses would have on the fleet capacity in Alabama and the resulting cost implications. The study also documents the myriad research studies and professional opinions offered on the potential safety effects of equipping school buses with safety restraints/seat belts. Four seat configurations for the school buses were analyzed. The first configuration represents the most common current bus seating configuration without seat belts, 3 seats on each side of the aisle and 12 rows (3/3-12). The physical space required for seat belt hardware may result in a loss of a row of seats and may reduce the number of students seated per row. Thus, three more configurations were studied: loss of a row of seats (3/3-11), loss of one seat per row (3/2-12), and loss of both a row of seats and a seat per row (3/2-11). The capacity for each configuration for each bus using current pupil loads was determined. The costs associated with installation of seat belts, and purchase and operation of new buses were obtained. Should school bus seat belts become mandatory in Alabama, the results obtained in this study can be used by any school system to determine the optimum configuration for their pupils, which will identify the number of additional buses that must be purchased by the school system. This study found that many of the buses that would become overloaded due to seat belt installation and the resultant loss of seating will be carrying only a few excess pupils. Transportation supervisors may be able to handle such overloads by transferring these pupils to other buses or by adjusting their bus routes to minimize purchase of new buses. Additional suggestions for handling bus overloads were offered in the body of this report.

Trajectory-Based Signal Control in Mixed Connected Vehicle Environments

Journal of Transportation Engineering, Part A: Systems, 2021

AbstractThe emerging connected vehicle (CV) technology has introduced the opportunity to improve ... more

Seat Belt Use on Alabama School Buses

The Alabama State Department of Education commissioned a study of school bus seat belt use on the... more The Alabama State Department of Education commissioned a study of school bus seat belt use on the basis of 12 buses (less than 1% of the fleet) equipped with seat belts and digital camera systems. The initial year of the study established baseline rates for normal situations. About 64,000 pupil observations were gathered from 11 buses on Tuesday through Thursday afternoon routes and from one control bus on Monday through Friday morning and afternoon routes. Afternoon route seat belt use was estimated to be 65.9% on the basis of 44,000 of the observations made. Given the small sample size, this value should be considered representative of the fleet but not exact. Belt use varied widely from bus to bus (94.5% to 4.8%). The degree of scatter was confirmed by large values of the coefficient of variation. Trends were documented for variation by day of week, morning versus afternoon, time on route, effects of bus aides, and changes in use over the school year. The findings confirmed the o...

Factors associated with driver injury severity of lane changing crashes involving younger and older drivers

Accident Analysis & Prevention

Injury-severity analysis of lane change crashes involving commercial motor vehicles on interstate highways

Journal of Safety Research

Factors associated with driver injury severity of lane changing crashes involving younger and older drivers

by Abhay Lidbe and Elsa Tedla

Accident Analysis & Prevention

Injury-severity analysis of lane change crashes involving commercial motor vehicles on interstate highways

by Abhay Lidbe, Elsa Tedla, and kofi Adanu

Journal of Safety Research

Analytical Techniques for Evaluating the Implementation of Adaptive Traffic Signal Control Systems

by Abhay Lidbe and Elsa Tedla

Journal of Transportation Engineering, Part A: Systems

Adaptive traffic signal control (ATCS) reduces congestion, improves travel time reliability, and ... more Adaptive traffic signal control (ATCS) reduces congestion, improves travel time reliability, and prolongs the effectiveness of traffic signal timing. The objective of this paper is to demonstrate different data sources and analysis techniques to compare the arterial performance for before, during, and after ATCS implementation. This paper presents several analyses using field-collected travel time data and simulation modeling techniques. The paper demonstrates that different sources of travel time data can be used to characterize the corridor performance under ATCS. Although corridor travel time is the traditional way to assess the improvements from the newer technologies, other measures need to be looked at for objective evaluation of the new systems. It is recommended to use multiple evaluation techniques for better decision making as every technique has its own limitations. The methodologies discussed will help transportation engineers, planners, and policymakers to understand what analysis can be conducted at any point of an ATCS deployment to evaluate the system performance. As policies and timings are adjusted, this feedback is an effective way to continuously monitor the ATCS and quantify benefits.

Reduction of capacity and projected costs associated with seat belt installation on school buses

by Steven Jones and Elsa Tedla

This study examines the potential effects the installation of seat belts on school buses would ha... more This study examines the potential effects the installation of seat belts on school buses would have on the fleet capacity in Alabama and the resulting cost implications. The study also documents the myriad research studies and professional opinions offered on the potential safety effects of equipping school buses with safety restraints/seat belts. Four seat configurations for the school buses were analyzed. The first configuration represents the most common current bus seating configuration without seat belts, 3 seats on each side of the aisle and 12 rows (3/3-12). The physical space required for seat belt hardware may result in a loss of a row of seats and may reduce the number of students seated per row. Thus, three more configurations were studied: loss of a row of seats (3/3-11), loss of one seat per row (3/2-12), and loss of both a row of seats and a seat per row (3/2-11). The capacity for each configuration for each bus using current pupil loads was determined. The costs associated with installation of seat belts, and purchase and operation of new buses were obtained. Should school bus seat belts become mandatory in Alabama, the results obtained in this study can be used by any school system to determine the optimum configuration for their pupils, which will identify the number of additional buses that must be purchased by the school system. This study found that many of the buses that would become overloaded due to seat belt installation and the resultant loss of seating will be carrying only a few excess pupils. Transportation supervisors may be able to handle such overloads by transferring these pupils to other buses or by adjusting their bus routes to minimize purchase of new buses. Additional suggestions for handling bus overloads were offered in the body of this report.

Role of Passengers in Single-Vehicle Drunk-Driving Crashes: An Injury-Severity Analysis

by Steven Jones and Elsa Tedla

Safety, 2020

Background: Drunk-driving is a major crash risk factor, and crashes resulting from this risky beh... more Background: Drunk-driving is a major crash risk factor, and crashes resulting from this risky behavior tend to be serious and have significant economic and societal impacts. The presence of passengers and their demographics and activities can influence risky driving behaviors such as drunk-driving. However, passengers could either be an "enabling" factor to take more risks or could be an "inhibiting" factor by ensuring safe driving by a drunk-driver. Objective: This study examines whether the presence of passengers affects the contributing factors of single-vehicle (SV) drunk-driving crashes, by presenting a severity analysis of single-and multi-occupant SV drunk-driving crashes, to identify risk factors that contribute to crash severity outcomes, for the effective implementation of relevant countermeasures. Method: A total of 7407 observations for 2012-2016 from the crash database of the State of Alabama was used for this study. The variables were divided into six classes: temporal, locational, driver, vehicle, roadway, and crash characteristics and injury severities into three: severe, minor, and no injury. Two latent class multinomial logit models-one each for single-and multi-occupant crashes-were developed, to analyze the effects of significant factors on injury severity outcomes using marginal effects. Results: The estimated results show that collision with a ditch, runoff road, intersection, winter season, wet roadway, and interstate decreased the probability of severe injuries in both single-and multi-occupant crashes, whereas rural area, road with downward grade, dark and unlit roadway, unemployed driver, and driver with invalid license increased the likelihood of severe injuries for both single-and multi-occupant crashes. Female drivers were more likely to be severely injured in single-occupant crashes, but less likely in multi-occupant crashes. A significant association was found between severe injuries and weekends, residential areas, and crash location close (<25 mi ≈40.23 km) to the residence of the at-fault driver in multi-occupant crashes. Sport utility vehicles were found to be safer when driving with passengers. Conclusions: The model findings show that, although many correlates are consistent between the single-and multi-occupant SV crashes that are associated with locational, roadway, vehicle, temporal, and driver characteristics, their effect can vary across the single-and multi-occupant driving population. The findings from this study can help in targeting interventions, developing countermeasures, and educating passengers to reduce drunk-driving crashes and consequent injuries. Such integrated efforts combined with engineering and emergency response may contribute in developing a true safe systems approach.

Public transport and health outcomes in rural sub-Saharan Africa – A synthesis of professional opinion

by Steven Jones and Elsa Tedla

Journal of Transportation and Health, 2016

Much of the recent transport focus in rural sub-Saharan Africa (SSA) has been on road building an... more Much of the recent transport focus in rural sub-Saharan Africa (SSA) has been on road building and upgrading as opposed to the provision of public transport. The literature reveals evidence of significant negative public health outcomes associated with crashes and pollution attributable to rural transport. We report the results of a synthesis of professional opinion obtained from in-person interviews and an internet survey on health issues related to the provision of public transport in rural SSA. Field interviews were conducted as semi-structured dialogues with some 40 transportation and public health professionals in the capital cities of Ethiopia, Ghana and Kenya. Additionally, 86 responses to an Internet survey were received from 38 African countries. Poor mechanical conditions of vehicles and risky driving behaviours were reported to be an important source of injury from rural road crashes. The factors contributing to unsafe rural public transport were attributable to economic barriers to proper operation. Although there was some mismatch among the survey and interview results and the literature, public transport was shown to be an important potential source of air pollution exposure. The overwhelming conclusion is the lack of true understanding of the health impacts of rural air pollution in relation to basic needs for provision of safe mobility. The findings reflect the awareness of various professional communities and emphasise the complexity of the relationship between rural public transport and public health. Transport and health relationships in places such as rural sub-Saharan Africa are further complicated by the fact that there is such significant potential for positive health outcomes attributable to transport through enhanced access to healthcare, education, commerce, etc. Systematic epidemiological research is needed to fully understand the trade-offs between rural mobility and its impacts to public health in rural sub-Saharan Africa.

Public transport and health outcomes in rural sub-Saharan Africa – A synthesis of professional opinion

by Elsa Tedla, Steven Jones, and Seth Appiah-Opoku

Journal of Transport & Health, 2016

Much of the recent transport focus in rural sub-Saharan Africa (SSA) has been on road building an... more Much of the recent transport focus in rural sub-Saharan Africa (SSA) has been on road building and upgrading as opposed to the provision of public transport. The literature reveals evidence of significant negative public health outcomes associated with crashes and pollution attributable to rural transport. We report the results of a synthesis of professional opinion obtained from in-person interviews and an internet survey on health issues related to the provision of public transport in rural SSA. Field interviews were conducted as semi-structured dialogues with some 40 transportation and public health professionals in the capital cities of Ethiopia, Ghana and Kenya. Additionally, 86 responses to an Internet survey were received from 38 African countries. Poor mechanical conditions of vehicles and risky driving behaviours were reported to be an important source of injury from rural road crashes. The factors contributing to unsafe rural public transport were attributable to economic barriers to proper operation. Although there was some mismatch among the survey and interview results and the literature, public transport was shown to be an important potential source of air pollution exposure. The overwhelming conclusion is the lack of true understanding of the health impacts of rural air pollution in relation to basic needs for provision of safe mobility. The findings reflect the awareness of various professional communities and emphasise the complexity of the relationship between rural public transport and public health. Transport and health relationships in places such as rural sub-Saharan Africa are further complicated by the fact that there is such significant potential for positive health outcomes attributable to transport through enhanced access to healthcare, education, commerce, etc. Systematic epidemiological research is needed to fully understand the trade-offs between rural mobility and its impacts to public health in rural sub-Saharan Africa.

Comparative assessment of arterial operations under conventional time-of-day and adaptive traffic signal control

by Steven Jones and Elsa Tedla

This paper compares three principal arterial corridors in Alabama under both conventional and ada... more This paper compares three principal arterial corridors in Alabama under both conventional and adaptive traffic signal control (ATSC). The corridors differ in their physical and operational characteristics. The comparison is conducted through microsimulation analysis of each corridor under their latest time-of-day (TOD) signal operations compared with the same field conditions (i.e., traffic volumes, geometry, access management) operating under Sydney Coordinated Adaptive Traffic System (SCATS) control. The three corridors greatly differ in the traffic saturation levels. Thus, the objective of this paper is to analyze and compare the performance of SCATS under varying saturation conditions. The comparison is based on various performance measures, including travel time, delay, average speed, and queue lengths under TOD and SCATS control. Based on the data and analysis results, a general conclusion is reached that in addition to the traditional ways to assess network performance, a range of other performance measures at various scales (i.e., network, corridor, sub-corridor, intersection) should be used to evaluate ATSC depending on overall policy goals. Under SCATS control, shorter side-streets queue lengths and shorter cycle-to-cycle queue lengths contribute to the network-wide performance gains. The improved network-wide performance is also attributed to the lower delays on side-streets and left-turn movements with SCATS. However, SCATS shows immediately measurable operational improvements only on unsaturated networks. SCATS shows less direct improvements in the network-wide performance measures for saturated conditions due to less ability to adapt and give more constrained vehicle movements.

Feasibility Assessment for Implementing Adaptive Traffic Signal Control

by Steven Jones, Abhay Lidbe, and Elsa Tedla

ASCE Journal of Transportation Engineering, 2018

Adaptive traffic control systems (ATCS) continuously adapt to changing traffic in order to improv... more Adaptive traffic control systems (ATCS) continuously adapt to changing traffic in order to improve traffic performance at signalized intersections. Typical before-after studies evaluate the success of ATCS deployments by assessing only the postimplementation traffic performance. Fully assessing the feasibility of ATCS implementation, however, requires evaluating the changes in long-term ATCS performance with changing traffic demands. This paper illustrates the assessment of long-term ATCS performance of two study corridors. The study uses volume=capacity (v=c) ratio to evaluate the effects of changing corridor flow on corridor-wide delay benefits. The results show that the Sydney Coordinated Adaptive Traffic System (SCATS) improves corridor flow and decreases corridor-wide delays up to a point of ineffectiveness, beyond which the ATCS performance begins to decrease. The ineffectiveness point helps in deriving a reasonable estimate for the magnitude and duration of potential ATCS deployment benefits.