Research Papers - Department of Civil Engineering

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An analysis of signalized intersections: Case of traffic light failure
(IEEE, 2017-01-27) Mohamed Mafas, A. M; Amarasingha, N
Traffic congestion due to failure of traffic lights is one of the problems in Colombo. To study traffic congestions due to failure of traffic lights, the traffic characteristics at intersections should be investigated. Capacity of the intersection is the main factor influenced for congestions. Data were collected at three intersections Malabe, Battaramulla and Rajagiriya and capacity of each identified. The capacity of each intersection was studied according to the Peak Hour Malabe and Rajagiriya had PHF of 0.95 and Battaramulla had the value of 0.91. Accordingly, the effective simple suggestions to manage these intersections may be introduction of telephone booth and police cabin to use the case of emergency.
Open Access
Characteristics of Motorcycle Crashes
(KDU IRC 2015, 2015-11) Amarasingha, N
Motorcycles are popular in Asian countries including Sri Lanka and it is becoming an important part of transportation in the country. Despite its popularity, little research has been conducted to study the impact of motorcycles on road safety in Sri Lanka. The objective of this study was to investigate the risk factors of crashes involving motorcycles. Data was obtained from Police crash records which contain details of police-reported crashes, at all severity levels that occurred in Sri Lanka. Various characteristics such as environment, roadway, driver, and vehicle are analysed investigating the Oddsratios so that potential countermeasures can be developed to improve roadside safety. Motorcycle crashes are rapidly increased in Sri Lanka last five years. More frequent crash conditions for motorcycle crashes occurred while driving on rural roadways, driving during week days in heavy traffic, and driving newer motorcycles. Dry road surfaces, clear weather conditions predominantly characterized motorcycle-crashes. This study adds detailed information about characteristics of motorcycle crashes and measures to improve motorcycle safety in Sri Lanka to the transportation safety literature.
Open Access
Characteristics of Railway-Roadway Level Crossings at Coastal Railway Line in Sri Lanka
(KDU IRC 2017, 2017) Amarasingha, N; Gunathilaka, O. H. D. C; Ragulan, K; Aravinda, M. P. N; Fernando, W. S. H. R
Rail transportation is a safe, efficient, continuously operating sustainable transportation mode, in all-weather conditions, and light conditions. Along with these advantages, the role of rail transport has become increasingly important. Therefore, it is important to investigate the characteristics of the railway-roadway level crossings in Sri Lanka. Railway-roadway level crossings at coastal railway line from Aluthgama to Ambalangoda were visited to collect the roadway, railway, traffic, environmental, and crash data. Out of 51 crossings that observed in this study, about 94.1% of railway-roadway level crossings were facilitated with active safety measures. About 7.0% of railway-roadway level crossings were without gates and among them 33.3% of crossings were facilitated with passive safety measures and other crossings were under unsafe conditions. Several problems related to railway-roadway level crossing were identified. The collected data could be utilized to develop various statistical models for identifying relationships between the number of crashes and level crossing characteristics. It could be used to identify potential highcrash prone railway-roadway crossings and key factors which increase the number of crashes.
Open Access
CHARACTERISTICS OF THREE-WHEELER CRASHES
(the 5th International Research Symposium on Engineering Advancements, SAITM, Colombo, Sri Lanka, 2015) Amarasingha, N
Despite its popularity in Sri Lanka, little research has been conducted to study the impact of three wheeler on road safety. The objective of this study was to investigate the characteristics of crashes involving three wheelers in Sri Lanka. The different driver, environmental, vehicle, and road related factors that affected three wheeler crashes were identified. More frequent crash conditions for three wheeler crashes occurred while driving on rural roadways, driving during week days in heavy traffic, and driving newer vehicles. It also showed that intersection crashes, and two vehicle crashes are more frequent in Sri Lanka. This study adds detailed information about characteristics of three wheeler crashes to the transportation safety literature.
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The effect of roadside elements on drivers' speed selection and lateral position on road
(IEEE, 2017-01-27) Lankathilake, T. N; Amarasingha, N
Highway related crashes are considered as one of most concerned types of problems in the modern world. Run-Off-Road (ROR) crashes could be identified as the most critical among highway related crashes. Previous research studies on Traffic Engineering has found that the road side elements will have a positive influence toward ROR crashes. Hence, the study explores the relationship of roadside elements with drivers' speed selection and lateral position. In this research study, the effect of road side vegetation and utility poles on drivers' speed selection and lateral positioning was evaluated. A straight roadway section and horizontal curve roadway section with varying road side vegetation were selected to get the required data for the study. Fifty vehicle were observed at each location to get the speeds and lateral positions. Collected data was analyzed using Multiple Regression Analysis technique to generate models to find drivers' speed selection and lateral positioning of vehicle on road. Study found that in lightly vegetated roadways, subjects drove speedier and drove much near the edge of the road. At the point when the scene changes into more vegetated, subjects drove much slower and drove near to the center of the road. The models demonstrate that the impact of road side vegetation way much higher in curved roads areas than straight segments. Therefore, it is recommended to post a speed limit sign and proper monitoring system at each critical curved roadway section in the country.
Embargo
Estimating the fuel loss during idling ofvehicles at signalized intersections in colombo
(2017-01-27) Nimesh, L; Alwis, V; Amarasingha, N
The fuel consumption of the vehicles is increasing day by day as a result of enhanced trip lengths, personal mode of transport, and congested intersections. The drivers normally keep their vehicle engine on while waiting for their turn to cross the intersection at signals, and a result of this extra fuel is consumed. This small amount of fuel wastage becomes a huge quantity when aggregated over number of cycles per day and number of signalized intersections. This study was carried out in Colombo, commercial capitals of Sri Lanka. For estimating the excess fuel consumed by vehicles during idling at signalized intersections, two signalized intersections with medium traffic volumes were considered. The selected signalized intersections were Borella and Narahenpita. The primary data for this research study, traffic volume and idling delay were obtained through field surveys. Required vehicle idling fuel consumption data were obtained from previous research. It was observed that the presence of heavy traffic congestion at the signalized intersections was the main reason for huge amount of fuel wastage from the vehicles. After the implementation of remedial measures, which are suggesting in this study, fuel loss during idling of vehicles at the signalized intersections can be reduced.
Open Access
Estimation of Person-Kilometers of Travel in Sri Lanka
(SLIIT, 2022-02-11) Gunathilaka, S; Amarasingha, N; Lakmali, M; Perera, C
Person Kilometers of Travel (PKT) provides all trip information of an individual including trips by motorized, non-motorized, public or informal public transport modes. Estimating PKT in developing countries seems much important as PKT is one of key parameters in transport planning and policy making. Since PKT focuses on an individual, it is influenced by socio demography of the person. However, timely PKT is not estimated by relevant agencies of Sri Lanka. The study focused on estimating PKT in Sri Lanka with travel mode distributions. A paper-based travel survey was conducted over all administrative districts in Sri Lanka for collecting trip information and socio demographic factors of people. 9,012 people participated in surveys resulting a 77.62% response rate. Respondents were asked to provide information of their trips in a typical week, in special holidays and seasons, information on travel modes and their socio demographic information. Data obtained from surveys were aggregated to annual level and weighted in order to obtain PKT/person/year under each socio demographic category. Weightages were estimated using census data in each administrative district. The study came up with important findings; weighted PKT estimations and travel mode distributions in each administrative district. Further, statistical comparisons of PKT estimates among different socio demographic groups and districts were conducted using One-Way Analysis of Variance (ANOVA) test. These findings were key contributions to the existing literature in the country.
Embargo
Estimation of vehicle kilometers travelled in southern province, Sri Lanka
(IEEE, 2017-01-27) Weerasekera, T. D; Amarasingha, N
Estimation of vehicle kilometers travelled (VKT) is used in traffic and transport planning for various purposes such estimating the emissions, estimating energy consumption, analyzing crashes, assessing traffic impact, and making road safety policy. Therefore, it is crucial to have an accurate timely estimation of VKT. Both traffic and non-traffic measurement methods are popular among the transport planners and researchers. Very few studies have conducted in Sri Lanka for estimating the VKT. This study proposes to estimate the VKT based on the number of household daily trips, which are collected through the interviews. The interviewer records the mode of travel, total number of kilometer travelled, and number of passengers. The socio-demographic information is also collected and this includes age, gender, employment status, income and residential area. The estimation of total VKT are derived from survey respondents' total number of kilometers each travelled during the previous 12 months in Southern Province, Sri Lanka. The collected data are also used to estimate the personal kilometer travelled and characteristics of travelers in Southern Province.
Embargo
Gender differences of young drivers on injury severity outcome of highway crashes
(Pergamon, 2014-06-01) Amarasingha, N; Dissanayake, S
Problem: Gender differences of young drivers involved in crashes and the associated differences in risk factors have not been fully explored in the United States (U.S.). Accordingly, this study investigated the topic, where the odds ratios (ORs) were used to identify differences in crash involvements between male and female young drivers. Method: Logistic regression models for injury severity of young male drivers and young female drivers were developed. Different driver, environmental, vehicle, and road related factors that have affected young fe- male drivers' and young male drivers' crash involvements were identified using the models. Results: Results in- dicated that some variables are significantly related to female drivers' injury risk but not male drivers' injury risk and vice versa. Variables such as driving with valid licenses, driving on weekends, avoidance or slow maneu- vers at time of crash, non-collision and overturn crashes, and collision with a pedestrian were significant vari- ables in female driver injury severity model but not in young male driver severity model. Travel on graded roadways, concrete surfaces, and wet road surfaces, collision with another vehicle, and rear-end collisions were variables that were significant in male-driver severity model but not in female-driver severity model. Summary: Factors which increase young female drivers' injury severity and young male drivers' injury severity were identified. This study adds detailed information about gender differences and similarities in injury severity risk of young drivers. Practical applications: It is important to note that the findings of this study show that gender differences do exists among young drivers. This sends a message to the industry that the transportation profes- sionals and researchers, who are developing countermeasures to increase the traffic safety, may need to pay attention to the differences. This might be particularly true when developing education materials for driver train- ing for young/inexperienced drivers
Open Access
Household travel survey method for vehicle kilometers travel estimations: A case study in a developing country.
(2021-05-01) Gunathilaka, S; Amarasingha, N; Dissanayake, S; Lakmali, M
Vehicle Kilometers Travelled (VKT) represents number of kilometers travelled by vehicles during a specific period of time in a specific area of concern. Transportation planners, policy makers, urban planners, and estimators of vehicle emission, energy consumption and fuelprice encourage the calculation of VKT for various analytical purposes. However, in most of the developing countries VKT is not estimated due to data challenges. This study aimed at proposing a household travel survey method for estimating VKT in developing countries where timely VKT data are not available. Also, estimating Personal Kilometers Travelled (PKT) seems important in developing countries, since the majority is using public and non-motorized transport modes rather than personal vehicles in those countries. This proposed method allows to collect data that are needed for estimating both VKT and PKT together with socio demographic information. A case study was conducted in three different regions; Northern, Eastern and Southern areas of Sri Lanka, which is a developing country. Questions were asked regarding to trips in a typical week, trips in holidays, special seasons or vacations, number of passengers travelled, travel modes and, socio demography of the respondent. Pilot surveys were conducted prior to the actual surveys to verify the efficiency of developed questionnaire. Samples were taken satisfying all the selected socio demographic categories within the community. Collected data through surveys were aggregated to annual level and, weighted using relevant census and population data. Weighted VKT and PKT estimates were obtained under each selected socio demographic category. Also, VKT estimates were statistically compared for studying the travel behavior of people across different regions. ANOVA and Post Hoc tests were employed for statistical comparisons. These findings can efficiently be used for transport planning, policy making activities, emission calculations, energy consumption estimations etc. by transport and environmental agencies of the country. The case study revealed the experience of utilizing the household travel survey method in Sri Lanka, making it possible to be replicated in other developing countries as well.
Open Access
Introduction of a Simple Estimation Method for Lane-Based Queue Lengths with Lane-changing Movements
(Springer, 2023-03) Jayatilleke, S; Wickramasinghe, V; Amarasingha, N
Traffic congestions are increased globally due to rapid urbanization and expedited economic developments in many countries. Vehicle queue is a governing aspect of traffic congestion, studied over the past decades. Most of the existing queue estimation approaches are limited to homogeneous traffic conditions. However, the traffic conditions in many developing countries are heterogeneous and are heavily influenced by mixed vehicle composition, lane changing, and gap-filling behaviours. This study aims to estimate the queue length at signalized intersections having heterogeneous traffic conditions. The heterogeneity was assimilated with the consideration of Passenger Car Units (PCU) in the measurements of the traffic flow and the lane-changing movement within the considered road section. The influential factors of the queue length were contemplated with the arrival flow, discharge flow, outbound lane change, inbound lane change, and signal configuration. A Vector Auto Regression (VAR) model was developed to estimate queue length, with a lag time of 15 s for each variable. The results have indicated a higher accuracy in the queue estimation as well as the practical application for prediction, constituting the traffic characteristics of the formed vehicle queue. The R squared of the VAR model was 0.97, along with a Mean Absolute Percentage Error (MAPE) of 21.55%. The model estimation results of right turning lanes were well accurate with MAPE ranging from 15 to 17%, whilst for through movement lanes, accuracy was slightly low with MAPE in the range of 23–26%. The study manifests the functionality of the developed methodology for accurate queue estimations, asserting the practical applicability of VAR models in other locations constituting mixed traffic. © 2022, The Institution of Engineers (India).
Open Access
Investigating a method for rating Sri Lankan roads through identifying the factors affecting road safety
(SLIIT, 2022-02-11) Amarasingha, N; Ramanayake, D. M. S
Road safety assessment is imminent to reduce road accidents in Sri Lanka. The existing road safety assessments in other countries are inapplicable to Sri Lankan Road conditions as there are significant differences between the road conditions of Sri Lanka and other countries. This study aims to identify the governing roadside elements which are influential to the cause of accidents and can be used for road star rating. The study was conducted in three districts of Sri Lanka: Anuradhapura, Polonnaruwa and Kurunegala. The data for road characteristics were obtained through the Google Earth Web engine whereas accident data were collected from Sri Lanka Police. The variables such as road condition, road length, road width, delineation, shoulder condition, footpath, vehicle parking length, road divide status, roadside objects length, number of lanes, number of intersections, number of pedestrian crossings, and number of bus bays were analyzed to develop a Negative Binomial regression model considering the number of accidents as the dependent variable. The results reveal that six variables: number of lanes, road condition, number of intersections, road divide status, road section length and width of lane are significant towards the occurrence of accidents. Moreover, the results demonstrate the relationship between the road characteristics and the accident number which is crucial in road designing in order to reduce road accidents. The findings affirm the possibility in developing a road safety rating mechanism for Sri Lankan streets to standardize the road network with the international standards while enhancing the road conditions with reflecting to the required safety levels.
Open Access
Linear Regression Models to Evaluate Characteristics of Railway-Roadway Level Crossings in a Developing Country
(International Journal of Traffic and Transportation Engineering, 2018) Fernando, W. S. H. R; Amarasingha, N
Railway-roadway level crossings are dangerous crash prone locations and the safety at these locations is of utmost importance. The objective of this research was to analyze the contributing factors of railway-roadway level crossing crashes. Crash data at railway- roadway level crossings, level crossing characteristics and both railway and roadway characteristics were collected along the coastal line from Pettah to Aluthgama in Sri Lanka. Seventy-seven level crossings were identified along this railway route. The data were collected using field surveys and site visits. The Multiple linear regression analysis was used to compare how a considered set of independent variables affects the dependent variable which was the crash data. According to the multiple linear regression analysis, the distance to nearest curvature from Colombo direction and Galle direction and the available traffic control system at the level crossings were not significant predictors of the occurrence of crashes at level crossings. The sight distances from the seaside and the land-side were significant predictors of crash data according to the regression model results. The sight distance from the seaside had a higher impact than the sight distance from the land side according to the standardized coefficients obtained from the model. The dangerous and hazardous level crossings along the selected route were identified through the detailed analysis of the crash data. Enhancements that could improve the standards of Galvanized Iron (GI) gates were identified and increasing the GI gate operator’s salary was also proposed.
Open Access
Modelling the Risk of Pedestrians in Walkways
(SLIIT, 2022-02-11) Amarasingha, N; Deshani, S
Pedestrians engaged crashes were increased day by day in the world. There is a high risk of accidents for pedestrians when crossing the road than walking on the road. To minimize the crash rate on pedestrians it is important to know about the risks faced by pedestrians on the road. This study aimed to report pedestrians’ perceptions of risks while walking and crossing the road. A questionnaire survey was carried out to get the data about pedestrians’ perceptions of risks while walking and crossing the road in Matara district. Data were collected with questions with a five-point scale during August and September 2021 from 225 females and 175 males. The collected data were validated by estimating the Cronbach Alpha values. And analyzed using chi-square tests and multinomial logistic regression analysis. The results of the study were shown the usage of that technical device while walking on the road is the most reported (66.2%) pedestrian risk in the walkways. Whereas crossing the road without using pedestrian crossings is the most reported risk (73%) during the time of crossing the road. The chisquare test results of the survey were indicated that some of the self-reported risks have a significant association with age and gender. Male pedestrians involved with risky behaviours than female pedestrians because male pedestrians have high observed values than the expected values in the reported risks. Age groups, less than 18 years and 18-30 pedestrians were mostly engaged with risky behaviours on the road. Their observed values in the pedestrian risks especially in using technical devices on the road are higher than the observed values compared to other age groups. When the average walking distance of pedestrians per day is increased, accidents happening on pedestrians is also increased. The results of this study would help infrastructure designers to make safer roads.
Open Access
Optimization of VISSIM Driver Behavior Parameter Values Using Genetic Algorithm
(Creative Commons Attribution, 2023-02-13) Gunarathne, D; Amarasingha, N; Kulathunga, A; Wicramasighe, V
Modeling effective vehicular traffic is a highly contested topic, especially in developing countries like Sri Lanka, which has a wide range of driving conditions. VISSIM microsimulation software is currently used by Road Development Authority (RDA) and relevant authorities to perform traffic management solutions in Sri Lanka. However, it is required to do modifications to the existing driver behavior parameter values to effectively reflect the realistic traffic conditions observed in the real-world in the simulated model. The main purpose of this study is to calibrate the VISSIM driver behavior parameter values using a genetic algorithm (GA). The methodology and results of the VISSIM model’s sensitivity analysis and calibration, which was developed for the Malabe three-legged signalized intersection, are presented in this study. A sensitivity analysis was used to find the most sensitive driver behavior parameters. Using the multi-objective GA optimization tool in the MATLAB software's optimization toolbox, the optimum driver behavior parameter values for these identified most sensitive driver behavior parameters were determined. The findings revealed that GA optimization is effective in reducing the difference between observed and simulated results.
Open Access
Pedestrian Crossing Behavior at Three Urban Signalized Intersections in Colombo
(2019) JAYASINGHE, J. A. D. M. N; Amarasingha, N
The pedestrians crossing behavior at signalized intersections has become one of the main factors contributing intersections related crashes. Understanding the pedestrian crossing behavior is important as the behavior of these vulnerable group are random and inconsistent, which in turn led to make the objective of this study. Waiting endurance times of pedestrians in three urban intersections were studied during both peak and off-peak hours. Data on pedestrian characteristics were extracted from recorded videos and coded the eight different characteristics of pedestrians. The behavioral differences among gender and age groups were examined including the identification of the different crossing patterns. The results showed that most of the male pedestrians and old pedestrians tend to produce violent crossing characteristics. It was also noted that many pedestrians neglect to adhere to a straight path during crossing.
Open Access
Performance Prediction Models for Flexible Pavements in Sri Lanka
(SLIIT, 2022-02-11) Amarasingha, N; Opanayake, P
The pavement prediction model forecasts the future PCI ratings based on pavement category, thickness, traffic, pavement life period and existing PCI rating. Nevertheless, with time and inclusion of newer pavement types, there was a need to adjust the prevailing pavement performance models. In addition to, pavements management systems need to develop new models for newer pavement types as well. Some developed pavement performance models in the earlier for the Road Development Authority (RDA) Sri Lanka is used by the roadway segments to predict the future condition and rehabilitations of its network. The available data collections in the roadway agencies in Sri Lanka was used for the research study and the methodology and the analysis section depended on that data collection. Probably we were given the IRI data collections which were done in southern expressway section in Sri Lanka. Based on that data, the analysis part was done for determine the pavement roughness deterioration curves. With a comparison of the developed models, the most suitable model was taken at 95% confidence level with 0.8009 R2 value. This study displays outcomes about of standardizing the present performance models, and creating unused models for the different asphalt forms within the roadway network in Sri Lanka. A comparison of IRI progression with pavement age and traffic volume is also conducted to see if there are major differences between such models developed in other countries. The anticipated expectations condition of the asphalts is utilized in assessing its outstanding benefit life to disappointment, which is of prompt utilize in prescribing future upkeep and recovery necessities for the arrange.
Open Access
Recursive Image Segmentation for Vehicular Traffic Analysis
(KDU IRC 2020, 2020) Eeshwara, M; Thilakumara, R; Amarasingha, N
Many methods have been proposed for image segmentation in vehicular traffic analysis using traffic camera video footage. However, isolation of moving objects with perfect object boundaries has been a challenging problem in vehicular traffic analysis. Usually these vehicle objects are extracted inside rectangular boundaries with extra irrelevant background image pixels from other objects included in the analyzed image. Thus using such segmentation methods in vehicle identification using video is not favorable for feature extraction for classification of vehicle category. This work proposes a method to deal with irregular shaped image segmentation for vehicle identification using a recursive algorithm. A binary thresholded image composed of white and black pixels is filtered with a 2D low pass filter to isolate irregular shaped image boundaries of objects. Then recursive image segmentation is applied on the filtered binary image. White pixels in the 2D filtered image are used to identify the presence of the object. If the neighboring pixels of the pixel of interest are also white, then those neighboring pixels are recursively processed the same way to account for the extent of the object. This recursive collection of pixels bounded by an irregular shaped boundary is continued until neighboring pixels are significantly different in color from the pixel of interest. From this recursive image segmentation algorithm, extraction of all pixels of odd shaped objects done in an efficient manner. Accordingly, pixels count, height and the width of the object are recorded. This image segmentation method has been successfully applied to identify vehicle categories in traffic video sequences.
Open Access
Red Light Running Violations of Four Intersections in Colombo Suburban
(2019) Amarasingha, N; ILHAAM, M. M
Four signalized intersections were selected which located in Colombo suburban, Battaramulla, Pelawatte, Thalawthugoda and Denzil kobbekaduwa. The observational survey was conducted for both peak and off-peak hours. Totally, 118,837 vehicles were observed and categorized them into three types; motor vehicles, motorcycles, and three wheelers. The Red Light Running (RLR) violation rate was 0.94% for motor vehicles, 2.44% for motorcycles, and 1.33% for three wheelers. The rate for motorcyclists was high in off-peak hours than peak hours. The RLR violation rate of motor vehicle drivers is lower than those for motorcyclists. The observed drivers were classified into two age groups: young and adult and more RLR violation rate was observed by young drivers than adults. Young drivers were found to be more likely to have risk-taking and adult drivers were found to be more likely to have opportunistic behaviors.
Open Access
Restraint usage characteristics and other factors associated with safety of children involved in motor vehicle crashes
(David Publishing, 2016) Dissanayake, S; Amarasingha, N
Involvement in road traffic crashes as vehicle occupants is a leading cause of death and serious injury among children. The objective of this study was to investigate crash severity factors and child safety restraint use characteristics in order to identify effective countermeasures to increase children’s highway safety. Characteristics and percentages of restraint use among child passengers aged 4~13 years were examined using highway crash data from Kansas. The association between restraint use, injury severity and characteristics of children involved in crashes were investigated using OR (odds ratios) and a logistic regression model, which was used to identify risk factors. Results showed that children, who were unrestrained, were seated in the front seat, traveling with drunk drivers and on rural roads, and traveling during nighttime was more vulnerable to severe injury in the case of motor vehicle crashes. The most frequent contributing causes related to crashes involving children included driver’s inattention while driving, failure to yield right-of-way, driving too fast, wet roads and animals in the road. Based on identified critical factors, general countermeasure ideas to improve children’s traffic safety were suggested, including age-appropriate and size-appropriate seat belt restraints and having children seated in the rear seat. Parents and children must gain better education regarding these safety measures in order to increase child safety on the road.