Faculty of Engineering

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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
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
A Study on Curbside Overtaking in Sri Lankan Streets
(SLIIT, 2022-02-11) Amarasingha, N; Eranga, A. L. C
Overtaking slower moving vehicles on the curbside under mix traffic condition is very common in Sri Lanka. The overtaking should never be done from the curbside as a rule of thumb, also rules and regulations regarding the overtaking should be never broken by drivers. Traffic accidents statistics reveal that main cause for serious accidents in Sri Lanka are excessive speed and incorrect overtaking. However, to the best of authors’ knowledge any research about curbside overtaking behavior has not been done so far. Objectives of this study are to investigate self-reported drivers’ overtaking behavior, and to find out drivers’ perspective about current rules and regulations on overtaking. A questionnaire form was developed, and a survey was conducted to collect data among 430 people in Colombo district. Chi–square tests and multinomial logistic regression analysis were done. Chi – square test results showed that among the selected variables, gender, age, occupation, driving license availability, charged a fine or accident due to curbside overtaking are the main factors that affect the curbside overtaking. The results of this study are facilitative to understand characteristics and some reasons behind curbside overtaking. Some methods such as educate public about dangerous overtaking and rules by organizing awareness programs, increasing fine for curbside overtaking, and imposing new laws are suggested to minimize the number of road accidents caused by overtaking slow moving vehicles on the curbside of the road.
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
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
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.
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
Travel Issues of Sri Lankan Females
(SLIIT, 2022-02-11) Karunarathne, T. S; Amarasingha, N
This research looks into the mobility problems that female travelers undergo, with an emphasis on Sri Lankan women. Males and females have different social and economic roles and obligations in most civilizations, and as a result, there are major gender variations in travel and transportation demands. The aim of this research is to investigate the mobility issues of females while traveling. This research analyzes mobility problems of female travelers with special reference to the Western province of Sri Lanka. This research targets to identify the mobility barriers which affect the females’ lifestyle, the problems, and threats females have faced, and the way they go through these problems. The socioeconomic, perspective of people, and travel behavior data were collected from 450 females by using a paper-based questionnaire in August 2021. Ordinal logistic regression analysis and Chi-square test were used to analyze the data. According to the results, sexual harassment while traveling was a significant problem. Among the respondents, 17% of respondents stated that sexual harassment was the most concerning security risk when traveling and 46.8% of female respondents faced sexual harassment when traveling by buses. Based on the types of harassment 26% of females experienced physical harassment as the most frequent harassment type and 25% experienced verbal harassment in public places or public transportation. Majority 42% of the females were strongly stated that they faced sexual harassment problems after dark. Poor maintenance of open public spaces, overcrowded buses/trains, lack of effective/visible police or civil guards, and lack of regulation on transport safety such as men dealing with or taking alcohol/drugs were factors that contribute to sexual harassment by females in public places and transport. The results of this analysis provide valuable insights into the mobility problems of female travelers in day-to-day life due to various reasons.
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.
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.

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