Proceedings of the 9th Asia Pacific Conference on Transportation & the Environment, 2017
Investment on transport infrastructure is a significant component in a country’s budget as it is ... more Investment on transport infrastructure is a significant component in a country’s budget as it is identified as a key factor to facilitate the country’s development. At the same time demand for transportation is positively correlated with the development. With this increasing demand for transport infrastructure and limited funding available, it is necessary to prioritise appropriate projects. Current appraisal practices at the early stages of projects fail to identify some important criterions and therefore, may ultimately end up not selecting the most appropriate project(s) which addresses contemporary concerns. Therefore the objective of this study is to identify a cost effective method and factors that should be considered in evaluating alternatives at the early stages of transport infrastructure projects. Both academic and grey literature was reviewed to identify current practises; methodologies and factors concerned in the recent past. Most of the time feasibility reports used descriptive format and often gave vague conclusions. Therefore the final selection of alternative(s) is implicit.  A performance matrix was developed in this study based on multi criteria analysis linear additive model. This method was primarily selected as it is easy to use in practise. In addition to the traditional criterions, this matrix contains new criterions that should be looked into with the current interests. A case study for Kandy expressway alternative selection based on this developed performance matrix is presented in this paper. In addition to the new matrix, a modified scoring system was used in the analysis to minimise the variations, as scores are given by different experts. Further, analysis was compared with the view of different experts and results of sensitivity analysis to address the possible arguments on weight given to each criterion.
Artificial islands are considered as a lucrative option for countries facing land shortage and co... more Artificial islands are considered as a lucrative option for countries facing land shortage and congestion. However, many countries such as, Australia, China, Canada, Hong Kong, Japan, UAE and Maldives have constructed such artificial islands for various reason. The Colombo Port City is an offshore artificial island which will be constructed next to the extended Colombo harbour in Sri Lanka which has a gross land area of 269 hectares (2.66 km). The main purpose of this city development is to offer an eminent potential for business, leisure and tourism, high quality of living not only for Sri Lankans but also for internationals. The land use of the new city will consist of residential developments, shopping areas, hotels, apartments, offices, educational institutes, recreation areas, a variety of sport facilities, marinas as well as a supporting transportation network. Colombo City is full with congestion most of the times and recent studies have found that the average vehicle speed h...
Road pricing has been a very common practice in the world for many decades. Tolls are charged fro... more Road pricing has been a very common practice in the world for many decades. Tolls are charged from road users as a tool to control traffic (congestion) or to raise finance (to recover capital and maintenance cost) or to control emissions. Public-Private Partnerships (PPP) or Build-Operate-Transfer (BOT) schemes have become common vii Kasun Shanaka for being with me all good and bad times and also his wife, Jinani. Hope we all had a good time in Melbourne during the last few years. Last but not least, I would like to thank my family for the endless support given throughout my candidature. I would like to take this opportunity to thank my parents, especially my mother for guiding me all the way from grade one to a doctorate. And also I extend my greatest appreciation to my lovely wife Anusha Attanayaka for understanding and having the patience to tolerate my extended work hours, sharing my problems and letting me focus on my research. Your support and courage from words to the action have made me complete this tough journey. In simple words, thank you so much for standing by me, especially during difficult times and helping me to manage everything in the best possible way. And also thank you so much for gifting me a lovely little princess, my little daughter Gesandi Aavya during my candidature. And thank you Aavya for not giving me much trouble while we were in Melbourne.
<jats:title>Abstract</jats:title> <jats:p>Trucks generate more externalities (e... more <jats:title>Abstract</jats:title> <jats:p>Trucks generate more externalities (environmental and social) than passenger vehicles, especially when trucks divert off freeways. When toll charges increase, such as the significant recent rise in Mel-bourne, Australia, more trucks tend to avoid toll roads (quality roads), generating more externalities. This diversion adds sub-stantial negative impacts on residents, the environment, and so-ciety. In fact, determining an optimum toll charge for freight ve-hicles is a crucial decision to be made by policymakers consid-ering socioeconomic aspects. The objective of this study is to develop an approach to design an optimal toll pricing scheme for multiclass vehicles, including specific truck types, consider-ing both direct costs and externalities. Additionally, the study developed an approach to identify the tradeoffs between vari-ous objectives of the designed scheme considering given con-straints. Nonlinear programming and user equilibrium techniques are used to model the problem, and the costs (direct costs and externalities) are quantified for Victoria, Australia. This nonde-terministic polynomial-time hard (NP-hard), nonconvex problem with nonlinear constraints was solved using the nondominated sorting genetic algorithm (NSGA) II. The model was applied to both a small-sized hypothetical network and a real network, with static demand conditions to illustrate differences between common toll schemes. Results are presented for Pareto-optimal solutions.</jats:p>
High toll charges force trucks to avoid quality roads, leading to increased emissions. We propose... more High toll charges force trucks to avoid quality roads, leading to increased emissions. We propose a model in this study to find an effective toll charging scheme to minimize total network vehicular emissions while maintaining reasonable revenue for investors. A bi-level modeling approach is used, where toll prices for multi-class vehicles are decided in the upper level and user response to toll charges are predicted using user equilibrium conditions with multi-class traffic assignment in the lower level. The model takes into consideration both toll revenue and total vehicle operating costs to produce an acceptable solution for both investors and road users. All major components of hazardous emissions were considered and estimated using secondary data, quantifying their impact on human health and the environment. The application of the model was illustrated using two networks considering different toll charging scenarios and near-optimal solutions were found for each toll-charging scenario. The results revealed that commonly used toll schemes are inefficient with respect to multi-stakeholder objectives. The optimized toll charging scheme was able to reduce the total emission costs of the network by 12 % compared to the toll scheme currently used by a toll facility in a real network in Melbourne, Australia.
Research in Transportation Business & Management, 2021
Abstract Stakeholder acceptance of any transport policy is crucial for its successful implementat... more Abstract Stakeholder acceptance of any transport policy is crucial for its successful implementation and sustainability. Many initiatives have failed in the past mostly due to stakeholder non-acceptability. As a result, the multi-stakeholder approach towards solving transportation problems is essential for sustainable transportation in the future. This study is focused on how different toll charging policies are perceived by various stakeholders and their level of acceptability. Various toll charging policies are considered where each toll scheme is optimizing at least one of the multi-stakeholder objectives such as user cost, social cost, environmental cost or the rate of return for investment. In addition, for comparison purposes, the currently established toll scheme is also added to the list. Even though each toll scheme is favoured by one or a few stakeholders (objectives) the overall acceptance from all the stakeholders is questionable. Therefore, the Multi-Actor Multi-Criteria Analysis (MAMCA) methodology has been used to evaluate all toll schemes and to identify the most suitable toll scheme considering multiple stakeholders. Different stakeholder opinions are explicitly considered in MAMCA and have been tested and used to successfully evaluate many solutions in the past. From this study, it was found that out of 10 alternatives 3 toll schemes are better at serving all stakeholders interests. It is important to note that in all three solutions heavy vehicles are charged less compared to light vehicles, which is against the present practice of charging heavy vehicles higher tolls.
Road user charging (RUC) has a long history as a mechanism to recover infrastructure maintenance ... more Road user charging (RUC) has a long history as a mechanism to recover infrastructure maintenance and capital costs. The present RUC systems are facing issues such as transparency, cross-subsidization, environmental concerns and reducing revenue due to the likes of lessening fuel tax as vehicles become more efficient. Therefore, this paper reviews the strengths and weaknesses of the present RUC mechanisms implemented in the world with respect to stakeholder problems and demands of the freight industry and to describe the need for a more appropriate, practical and sustainable approach that can be used in the future. Finally, a model is proposed that is transparent and considers usage-based charging addressing most of the weaknesses highlighted in the models reviewed. Further, it considers externalities produced by heavy vehicles into account. The model has the potential to provide answers to key stakeholder issues and will lead to a sustainable freight transport system in the future. Encouraging fuel-efficient modes, optimization of loading, routing and logistics systems, and long term land use planning are a few of them.
Journal of Transportation Safety & Security, 2016
Road traffic injury is a leading cause of mortality and morbidity in Sri Lanka. In 2014, 35,967 c... more Road traffic injury is a leading cause of mortality and morbidity in Sri Lanka. In 2014, 35,967 crashes were reported of which 6% were fatal, causing 2,440 deaths. Motorcycles account for more than 50% of the vehicles registered in the country and have been involved in over 50% of the total fatalities in 2014. Three-wheelers, being the second highest registered vehicle category in the country, have been involved in 16% of the fatalities in the same year. An analysis of motorcycle and three-wheeler crashes was done using the 'Sri Lanka Police Accident Database', vehicle registration details and population data. On average, 4 people died per day from motorcycle and three wheeler crashes in 2013. Not having a valid driving license upon a crash, rear end crashes, age group 21-25, single vehicle crashes were some of the significant risk factors associated with motorcycle crashes. Aggressive or negligent driving, crash being a rolled over crash, driver age group 26-30 were some of the significant factors associated with three wheeler crashes. Promotion of public transport, strict law enforcement on helmet usage, design change of three-wheelers to restrict narrow turns and more road safety education are suggested to mitigate this issue.
This paper critically evaluates traffic related performance of the Southern Expressway (SEW) in S... more This paper critically evaluates traffic related performance of the Southern Expressway (SEW) in Sri Lanka using basic traffic engineering parameters such as average speeds, acceleration-deceleration changes, root mean square acceleration, and positive kinetic energy. An on-road speed/time data sample was collected, and a driving cycle was developed to compare to well-established driving cycles worldwide. Ten traffic-related parameters were identified in order to evaluate the SEW using the collected data. Data was collected in proportion to the number of actual trips made by users on an average day using the on-board method; the segment-based method was adopted for cycle construction. Previously identified traffic-related parameters were used to evaluate and select representative cycle for the SEW from candidate cycles. The selected driving cycle was 1213 s in length. Average speed, average acceleration, and average deceleration were 80.6 km/h, 0.45, and 0.25 m/s 2 , respectively. Results showed that both average and running speeds of the SEW were significantly below compared to its posted speed limit, thereby increasing the travel time. Comparatively smooth driving behavior will improve the SEW's fuel and emission performances. This study created a platform with which future studies can evaluate performances of all operational and future expressways.
Financial constraints and lack of availability of traffic-related information significantly hinde... more Financial constraints and lack of availability of traffic-related information significantly hinder the development of driving cycles in developing countries. This paper proposes an economical, practical, accurate methodology for the development of driving cycles, including the development of a driving cycle for Colombo, Sri Lanka. The proposed methodology captures regional traffic and road conditions and selects a model that represents the collected data sample with minimum available traffic-related information. Existing methods were modified for route selection by dividing routes into links using nodes or physical junctions to minimize the number of trips required for data collection. Speed-time data for respective links were used to reconstruct speed-time profiles of identified origin-destination pairs. The on-board method was used for data collection, and the Markov chain theory was used to develop a transition probability matrix of state changes. An additional matrix was introduced to the existing method to improve model representativeness to the collected data sample.
The older population (>65 years) numbered 36.8 million in the United States in 2005. By 2030, the... more The older population (>65 years) numbered 36.8 million in the United States in 2005. By 2030, the number is estimated to be 71.5 million, almost twice as many. An increase in the older population means an increase in older drivers as well. As a result of the natural aging process, the possibility of older drivers being involved in crashes and sustaining severe injuries increases, according to past findings. The objective of this study was to identify characteristics of older drivers involved in crashes in Kansas as well as associated safety issues, which can be used to suggest potential countermeasures for improving safety. A detailed characteristic analysis was carried out for older, middle-aged, and younger drivers involved in crashes, using crash data obtained from the Kansas Department of Transportation, and comparisons were made among the groups. However, the characteristic analysis had no basis with regard to injury severity and hence, univariate statistical analysis was carried out to highlight these severities. In addition, a survey was conducted focusing on identifying older-driver behaviors, potential problems, and level of exposure to various conditions. From the severity analysis, it was found that injury severity of older drivers in crashes occurring on rural roads was significantly higher compared to those on urban roads. Therefore, a detailed analysis was carried out using the decomposition method and ordered probit modeling to identify contributing factors leading to the situation. According to the findings, the number of older male drivers involved in crashes was higher compared to older female drivers, even though older driver licensees' data indicate the opposite. Most of the older-driver-involved crashes occurred under good environmental conditions and at intersections. A majority of older drivers had difficulties associated with leftturn maneuvering and preferred to avoid high-traffic roads and other demanding conditions. Exposure to inclement weather conditions and difficulties associated with merging, diverging, and identifying speeds and distance of oncoming traffic have lead to higher crash propensity. In rural areas, driving in the wrong direction, failing to comply with traffic signs and signals, and speeding were identified as frequent contributing factors in high severe crashes.
Many models have been developed in the world to estimate emission inventories and fuel consumptio... more Many models have been developed in the world to estimate emission inventories and fuel consumption in the past and those models can be broadly categorized as either a travel based model or a fuel based model. Driving cycles can be considered as one of the major travel based models to estimate emission inventories. It can be used for various purposes such as setting up the emission standards, for traffic management purposes and also to determine the travel time. In the past, researchers have tried to use readily available, well established driving cycles in their environment which is different from the origin of the driving cycle in many aspects. Thus, the attempts have failed to give good quality results. This study attempts to critically evaluate the different methods used for driving cycle construction in different parts of the world under various conditions to propose a general suitable approach to develop a representative and economical driving cycle(s) for a given geographic location for set objectives.
A driving cycle is a speed time profile which represents the driving characteristics of a selecte... more A driving cycle is a speed time profile which represents the driving characteristics of a selected area. This can be of use to both legislative and non legislative purposes such as development of emission inventory, determination of fuel consumption etc. As driving cycles are dependent on the traffic constituents, driver behaviour and road conditions established driving cycles cannot be used in Sri Lanka. Hence the objective of this research is to develop a methodology and to constructa driving cycle(s) which represent given set of conditions in Sri Lanka such that it can be use to establish emission inventory in future. To achieve these objectives, it is necessary to collect and analyse the on road speed-time data on selected routes which will represent the driving patterns of urban or rural conditions. Due to the restriction of time and resources, study was limited to one transport corridor, anurban condition and for light vehicles only. A sample driving cycle was developed based on the data collected on the Galle Road, section from Katubedda to Fort using on board method. Cycle was developed using micro trip based cycle construction and computer application was developed to aid this purpose. In this study we observed average speed 21.37km/h, average running speed 25.78km/h, average acceleration 2.03km/h/s and average deceleration 2.02km/h/s with acceleration, deceleration, cruising and idling proportions of 27.37%, 23.70%, 31.43% and 17.49% respectively for selected urban condition. This study would facilitate the further studies on development of driving cycles for other conditions and could be of use for traffic engineering studies as well as sustainable development
Introduction of a roundabout is a proven method of minimizing delays and risks at an intersection... more Introduction of a roundabout is a proven method of minimizing delays and risks at an intersection simply due to the reduction in number of conflict points, implementation of give way rule, single directional circulation and reduced speed due to the lateral displacement. However, there arestill opportunities and desires for improvements in reducing the delay and increasing the safety at roundabouts. The safety risk and delay is significant when vehicular volume is high. Roundabout performance can degrade if precautions are not taken eitherduring the design or the operation phases. Therefore this study is focused on seeking traffic engineering solutions to minimize the delay and risk of accidents at roundabouts to be implemented at design and construction stages. During the study, it was realized that a solution should be obtained through both literature reviews and data analysis. Therefore a comprehensive literature review was carried out on related sub topics. Crash and geometric data were collected for two normal roundabouts and analysed. Increasing the diameter of the central island up to the required level specified by the guidelines, decreasing the approach curve radius, elevating the circulating carriageway with respect to the approach carriage by introducing a ramp for the entering vehicles are proposed for the roundabouts as traffic engineering solution
Proceedings of the 9th Asia Pacific Conference on Transportation & the Environment, 2017
Investment on transport infrastructure is a significant component in a country’s budget as it is ... more Investment on transport infrastructure is a significant component in a country’s budget as it is identified as a key factor to facilitate the country’s development. At the same time demand for transportation is positively correlated with the development. With this increasing demand for transport infrastructure and limited funding available, it is necessary to prioritise appropriate projects. Current appraisal practices at the early stages of projects fail to identify some important criterions and therefore, may ultimately end up not selecting the most appropriate project(s) which addresses contemporary concerns. Therefore the objective of this study is to identify a cost effective method and factors that should be considered in evaluating alternatives at the early stages of transport infrastructure projects. Both academic and grey literature was reviewed to identify current practises; methodologies and factors concerned in the recent past. Most of the time feasibility reports used descriptive format and often gave vague conclusions. Therefore the final selection of alternative(s) is implicit.  A performance matrix was developed in this study based on multi criteria analysis linear additive model. This method was primarily selected as it is easy to use in practise. In addition to the traditional criterions, this matrix contains new criterions that should be looked into with the current interests. A case study for Kandy expressway alternative selection based on this developed performance matrix is presented in this paper. In addition to the new matrix, a modified scoring system was used in the analysis to minimise the variations, as scores are given by different experts. Further, analysis was compared with the view of different experts and results of sensitivity analysis to address the possible arguments on weight given to each criterion.
Artificial islands are considered as a lucrative option for countries facing land shortage and co... more Artificial islands are considered as a lucrative option for countries facing land shortage and congestion. However, many countries such as, Australia, China, Canada, Hong Kong, Japan, UAE and Maldives have constructed such artificial islands for various reason. The Colombo Port City is an offshore artificial island which will be constructed next to the extended Colombo harbour in Sri Lanka which has a gross land area of 269 hectares (2.66 km). The main purpose of this city development is to offer an eminent potential for business, leisure and tourism, high quality of living not only for Sri Lankans but also for internationals. The land use of the new city will consist of residential developments, shopping areas, hotels, apartments, offices, educational institutes, recreation areas, a variety of sport facilities, marinas as well as a supporting transportation network. Colombo City is full with congestion most of the times and recent studies have found that the average vehicle speed h...
Road pricing has been a very common practice in the world for many decades. Tolls are charged fro... more Road pricing has been a very common practice in the world for many decades. Tolls are charged from road users as a tool to control traffic (congestion) or to raise finance (to recover capital and maintenance cost) or to control emissions. Public-Private Partnerships (PPP) or Build-Operate-Transfer (BOT) schemes have become common vii Kasun Shanaka for being with me all good and bad times and also his wife, Jinani. Hope we all had a good time in Melbourne during the last few years. Last but not least, I would like to thank my family for the endless support given throughout my candidature. I would like to take this opportunity to thank my parents, especially my mother for guiding me all the way from grade one to a doctorate. And also I extend my greatest appreciation to my lovely wife Anusha Attanayaka for understanding and having the patience to tolerate my extended work hours, sharing my problems and letting me focus on my research. Your support and courage from words to the action have made me complete this tough journey. In simple words, thank you so much for standing by me, especially during difficult times and helping me to manage everything in the best possible way. And also thank you so much for gifting me a lovely little princess, my little daughter Gesandi Aavya during my candidature. And thank you Aavya for not giving me much trouble while we were in Melbourne.
<jats:title>Abstract</jats:title> <jats:p>Trucks generate more externalities (e... more <jats:title>Abstract</jats:title> <jats:p>Trucks generate more externalities (environmental and social) than passenger vehicles, especially when trucks divert off freeways. When toll charges increase, such as the significant recent rise in Mel-bourne, Australia, more trucks tend to avoid toll roads (quality roads), generating more externalities. This diversion adds sub-stantial negative impacts on residents, the environment, and so-ciety. In fact, determining an optimum toll charge for freight ve-hicles is a crucial decision to be made by policymakers consid-ering socioeconomic aspects. The objective of this study is to develop an approach to design an optimal toll pricing scheme for multiclass vehicles, including specific truck types, consider-ing both direct costs and externalities. Additionally, the study developed an approach to identify the tradeoffs between vari-ous objectives of the designed scheme considering given con-straints. Nonlinear programming and user equilibrium techniques are used to model the problem, and the costs (direct costs and externalities) are quantified for Victoria, Australia. This nonde-terministic polynomial-time hard (NP-hard), nonconvex problem with nonlinear constraints was solved using the nondominated sorting genetic algorithm (NSGA) II. The model was applied to both a small-sized hypothetical network and a real network, with static demand conditions to illustrate differences between common toll schemes. Results are presented for Pareto-optimal solutions.</jats:p>
High toll charges force trucks to avoid quality roads, leading to increased emissions. We propose... more High toll charges force trucks to avoid quality roads, leading to increased emissions. We propose a model in this study to find an effective toll charging scheme to minimize total network vehicular emissions while maintaining reasonable revenue for investors. A bi-level modeling approach is used, where toll prices for multi-class vehicles are decided in the upper level and user response to toll charges are predicted using user equilibrium conditions with multi-class traffic assignment in the lower level. The model takes into consideration both toll revenue and total vehicle operating costs to produce an acceptable solution for both investors and road users. All major components of hazardous emissions were considered and estimated using secondary data, quantifying their impact on human health and the environment. The application of the model was illustrated using two networks considering different toll charging scenarios and near-optimal solutions were found for each toll-charging scenario. The results revealed that commonly used toll schemes are inefficient with respect to multi-stakeholder objectives. The optimized toll charging scheme was able to reduce the total emission costs of the network by 12 % compared to the toll scheme currently used by a toll facility in a real network in Melbourne, Australia.
Research in Transportation Business & Management, 2021
Abstract Stakeholder acceptance of any transport policy is crucial for its successful implementat... more Abstract Stakeholder acceptance of any transport policy is crucial for its successful implementation and sustainability. Many initiatives have failed in the past mostly due to stakeholder non-acceptability. As a result, the multi-stakeholder approach towards solving transportation problems is essential for sustainable transportation in the future. This study is focused on how different toll charging policies are perceived by various stakeholders and their level of acceptability. Various toll charging policies are considered where each toll scheme is optimizing at least one of the multi-stakeholder objectives such as user cost, social cost, environmental cost or the rate of return for investment. In addition, for comparison purposes, the currently established toll scheme is also added to the list. Even though each toll scheme is favoured by one or a few stakeholders (objectives) the overall acceptance from all the stakeholders is questionable. Therefore, the Multi-Actor Multi-Criteria Analysis (MAMCA) methodology has been used to evaluate all toll schemes and to identify the most suitable toll scheme considering multiple stakeholders. Different stakeholder opinions are explicitly considered in MAMCA and have been tested and used to successfully evaluate many solutions in the past. From this study, it was found that out of 10 alternatives 3 toll schemes are better at serving all stakeholders interests. It is important to note that in all three solutions heavy vehicles are charged less compared to light vehicles, which is against the present practice of charging heavy vehicles higher tolls.
Road user charging (RUC) has a long history as a mechanism to recover infrastructure maintenance ... more Road user charging (RUC) has a long history as a mechanism to recover infrastructure maintenance and capital costs. The present RUC systems are facing issues such as transparency, cross-subsidization, environmental concerns and reducing revenue due to the likes of lessening fuel tax as vehicles become more efficient. Therefore, this paper reviews the strengths and weaknesses of the present RUC mechanisms implemented in the world with respect to stakeholder problems and demands of the freight industry and to describe the need for a more appropriate, practical and sustainable approach that can be used in the future. Finally, a model is proposed that is transparent and considers usage-based charging addressing most of the weaknesses highlighted in the models reviewed. Further, it considers externalities produced by heavy vehicles into account. The model has the potential to provide answers to key stakeholder issues and will lead to a sustainable freight transport system in the future. Encouraging fuel-efficient modes, optimization of loading, routing and logistics systems, and long term land use planning are a few of them.
Journal of Transportation Safety & Security, 2016
Road traffic injury is a leading cause of mortality and morbidity in Sri Lanka. In 2014, 35,967 c... more Road traffic injury is a leading cause of mortality and morbidity in Sri Lanka. In 2014, 35,967 crashes were reported of which 6% were fatal, causing 2,440 deaths. Motorcycles account for more than 50% of the vehicles registered in the country and have been involved in over 50% of the total fatalities in 2014. Three-wheelers, being the second highest registered vehicle category in the country, have been involved in 16% of the fatalities in the same year. An analysis of motorcycle and three-wheeler crashes was done using the 'Sri Lanka Police Accident Database', vehicle registration details and population data. On average, 4 people died per day from motorcycle and three wheeler crashes in 2013. Not having a valid driving license upon a crash, rear end crashes, age group 21-25, single vehicle crashes were some of the significant risk factors associated with motorcycle crashes. Aggressive or negligent driving, crash being a rolled over crash, driver age group 26-30 were some of the significant factors associated with three wheeler crashes. Promotion of public transport, strict law enforcement on helmet usage, design change of three-wheelers to restrict narrow turns and more road safety education are suggested to mitigate this issue.
This paper critically evaluates traffic related performance of the Southern Expressway (SEW) in S... more This paper critically evaluates traffic related performance of the Southern Expressway (SEW) in Sri Lanka using basic traffic engineering parameters such as average speeds, acceleration-deceleration changes, root mean square acceleration, and positive kinetic energy. An on-road speed/time data sample was collected, and a driving cycle was developed to compare to well-established driving cycles worldwide. Ten traffic-related parameters were identified in order to evaluate the SEW using the collected data. Data was collected in proportion to the number of actual trips made by users on an average day using the on-board method; the segment-based method was adopted for cycle construction. Previously identified traffic-related parameters were used to evaluate and select representative cycle for the SEW from candidate cycles. The selected driving cycle was 1213 s in length. Average speed, average acceleration, and average deceleration were 80.6 km/h, 0.45, and 0.25 m/s 2 , respectively. Results showed that both average and running speeds of the SEW were significantly below compared to its posted speed limit, thereby increasing the travel time. Comparatively smooth driving behavior will improve the SEW's fuel and emission performances. This study created a platform with which future studies can evaluate performances of all operational and future expressways.
Financial constraints and lack of availability of traffic-related information significantly hinde... more Financial constraints and lack of availability of traffic-related information significantly hinder the development of driving cycles in developing countries. This paper proposes an economical, practical, accurate methodology for the development of driving cycles, including the development of a driving cycle for Colombo, Sri Lanka. The proposed methodology captures regional traffic and road conditions and selects a model that represents the collected data sample with minimum available traffic-related information. Existing methods were modified for route selection by dividing routes into links using nodes or physical junctions to minimize the number of trips required for data collection. Speed-time data for respective links were used to reconstruct speed-time profiles of identified origin-destination pairs. The on-board method was used for data collection, and the Markov chain theory was used to develop a transition probability matrix of state changes. An additional matrix was introduced to the existing method to improve model representativeness to the collected data sample.
The older population (>65 years) numbered 36.8 million in the United States in 2005. By 2030, the... more The older population (>65 years) numbered 36.8 million in the United States in 2005. By 2030, the number is estimated to be 71.5 million, almost twice as many. An increase in the older population means an increase in older drivers as well. As a result of the natural aging process, the possibility of older drivers being involved in crashes and sustaining severe injuries increases, according to past findings. The objective of this study was to identify characteristics of older drivers involved in crashes in Kansas as well as associated safety issues, which can be used to suggest potential countermeasures for improving safety. A detailed characteristic analysis was carried out for older, middle-aged, and younger drivers involved in crashes, using crash data obtained from the Kansas Department of Transportation, and comparisons were made among the groups. However, the characteristic analysis had no basis with regard to injury severity and hence, univariate statistical analysis was carried out to highlight these severities. In addition, a survey was conducted focusing on identifying older-driver behaviors, potential problems, and level of exposure to various conditions. From the severity analysis, it was found that injury severity of older drivers in crashes occurring on rural roads was significantly higher compared to those on urban roads. Therefore, a detailed analysis was carried out using the decomposition method and ordered probit modeling to identify contributing factors leading to the situation. According to the findings, the number of older male drivers involved in crashes was higher compared to older female drivers, even though older driver licensees' data indicate the opposite. Most of the older-driver-involved crashes occurred under good environmental conditions and at intersections. A majority of older drivers had difficulties associated with leftturn maneuvering and preferred to avoid high-traffic roads and other demanding conditions. Exposure to inclement weather conditions and difficulties associated with merging, diverging, and identifying speeds and distance of oncoming traffic have lead to higher crash propensity. In rural areas, driving in the wrong direction, failing to comply with traffic signs and signals, and speeding were identified as frequent contributing factors in high severe crashes.
Many models have been developed in the world to estimate emission inventories and fuel consumptio... more Many models have been developed in the world to estimate emission inventories and fuel consumption in the past and those models can be broadly categorized as either a travel based model or a fuel based model. Driving cycles can be considered as one of the major travel based models to estimate emission inventories. It can be used for various purposes such as setting up the emission standards, for traffic management purposes and also to determine the travel time. In the past, researchers have tried to use readily available, well established driving cycles in their environment which is different from the origin of the driving cycle in many aspects. Thus, the attempts have failed to give good quality results. This study attempts to critically evaluate the different methods used for driving cycle construction in different parts of the world under various conditions to propose a general suitable approach to develop a representative and economical driving cycle(s) for a given geographic location for set objectives.
A driving cycle is a speed time profile which represents the driving characteristics of a selecte... more A driving cycle is a speed time profile which represents the driving characteristics of a selected area. This can be of use to both legislative and non legislative purposes such as development of emission inventory, determination of fuel consumption etc. As driving cycles are dependent on the traffic constituents, driver behaviour and road conditions established driving cycles cannot be used in Sri Lanka. Hence the objective of this research is to develop a methodology and to constructa driving cycle(s) which represent given set of conditions in Sri Lanka such that it can be use to establish emission inventory in future. To achieve these objectives, it is necessary to collect and analyse the on road speed-time data on selected routes which will represent the driving patterns of urban or rural conditions. Due to the restriction of time and resources, study was limited to one transport corridor, anurban condition and for light vehicles only. A sample driving cycle was developed based on the data collected on the Galle Road, section from Katubedda to Fort using on board method. Cycle was developed using micro trip based cycle construction and computer application was developed to aid this purpose. In this study we observed average speed 21.37km/h, average running speed 25.78km/h, average acceleration 2.03km/h/s and average deceleration 2.02km/h/s with acceleration, deceleration, cruising and idling proportions of 27.37%, 23.70%, 31.43% and 17.49% respectively for selected urban condition. This study would facilitate the further studies on development of driving cycles for other conditions and could be of use for traffic engineering studies as well as sustainable development
Introduction of a roundabout is a proven method of minimizing delays and risks at an intersection... more Introduction of a roundabout is a proven method of minimizing delays and risks at an intersection simply due to the reduction in number of conflict points, implementation of give way rule, single directional circulation and reduced speed due to the lateral displacement. However, there arestill opportunities and desires for improvements in reducing the delay and increasing the safety at roundabouts. The safety risk and delay is significant when vehicular volume is high. Roundabout performance can degrade if precautions are not taken eitherduring the design or the operation phases. Therefore this study is focused on seeking traffic engineering solutions to minimize the delay and risk of accidents at roundabouts to be implemented at design and construction stages. During the study, it was realized that a solution should be obtained through both literature reviews and data analysis. Therefore a comprehensive literature review was carried out on related sub topics. Crash and geometric data were collected for two normal roundabouts and analysed. Increasing the diameter of the central island up to the required level specified by the guidelines, decreasing the approach curve radius, elevating the circulating carriageway with respect to the approach carriage by introducing a ramp for the entering vehicles are proposed for the roundabouts as traffic engineering solution
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Papers by Loshaka Perera