TRF - 2020

Permanent URI for this collectionhttp://192.248.9.226/handle/123/17957

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item: Conference-Abstract
Analysis on transport mode choices of school children in Colombo District, Sri Lanka
(Department of Civil Engineering, University of Moratuwa, 2020-12) Damsara, P; De Silva, D; Sirisoma, N; Perera, HLK
The increase in the usage of private transport modes for school trips has become a major reason for traffic congestion in Colombo District during peak hours. Colombo District consists of 402 functioning government schools, with a total student population of 374,995. Those schools have been categorized into four categories based on the availability of classrooms. According to the Ministry of Education, there is a limitation which is imposed on the distance from home to school, in the student enrollment process. However, it has been identified that the distances are exceeding the limitation, with respect to the school type and location. As a result, students choose different transport modes based on many factors such as accessibility, connectivity, safety, reliability and comfort. This study focuses on identifying the distances from home to school and the respective transport mode choice of the students in Colombo District. In addition, the factors which affect those school children to avoid public transport modes were analyzed. The quantitative research approach has been used in developing the research methodology in several phases such as factor identification, mode choices and demand distribution. Data collection has been conducted through a questionnaire survey which covers 28 selected schools under four categories, with a total sample size of 2875 in all Divisional Secretariat Divisions (DSDs) of Colombo District. Stratified sampling technique was used to collect data from the above school types. Schools which have classes in all streams up to advanced level (1AB schools) show the highest percentage of students (44%) who travel a distance of 2-10 km from home to school, while other school types show the highest percentage of students (49%) who travel a distance range of less than 2 km. Further, it has been identified that 1AB schools have some students who travel more than 25 km daily for their school trips. School van/bus services are the main mode of transport which is used by the students of schools located in Colombo Municipal Council (CMC) area, while public transport modes such as bus, train and “Sisu-Sariya school bus service” are the main modes of transport which are used by the students outside the CMC area. Active transport modes are the least popular mode of travel in both CMC and Non-CMC area (13% each), while private transport modes, which consists of car/van/jeep, motorbikes and three-wheelers contribute 25% in CMC area and 33% in Non-CMC area. Furthermore, it has been identified that longer travel times, longer waiting times, poor accessibility, less security and less comfort are the main reasons for the students in Colombo District, to not use public transport services. Even though there is a dedicated public transport service (“Sisu-Sariya”), which have been provided for school children, it has been found that there is a considerable usage of private transport modes for school trips in the district. Therefore, this study recommends a procedure to develop an improved public transport system for school trips including a model for trip distribution patterns, network connectivity and system planning to attract more students into public transport services.
item: Conference-Abstract
Application of intelligent transport system (ITS) in passenger boarding and alighting surveys
(Department of Civil Engineering, University of Moratuwa, 2020-12) Vidanapathirana, C; Thilakshan, T; Sharic, S; Bandara, S; Perera, HLK
Bus passenger transportation essentially requires continuous planning, evaluation and upgrading to maintain its level of service. Necessary traffic data including passenger counts, bus stop locations and corresponding demand, speed, relevant functional and infrastructure information have to collect regularly by the authorities to conduct such studies. Though there exist various conventional approaches for data collection, most of them are regarded as less effective in the present context. Global Positioning System (GPS) based applications in intelligent transport systems have proven to be efficient and cost-effective in identifying and tracking the geolocation of connected elements. Hence, with the intention of narrowing the technological gap, a holistic system that embodies both hardware components and software applications were developed for real-time data acquisition with remote access. This multidisciplinary engineering solution collects data mainly from two sources. Firstly, a mobile application was developed to facilitate the collection of trip-specific data. For every journey, at the departure, the surveyor can create a new trip in the app and input the origin, destination, date, surveyor’s position (front door, back door or middle door) and characteristics of the vehicle. Then a recurring sequence of features appears on the screen to record the GPS locations of bus stops, boarding and alighting counts at every bus stop, passenger demographics and the characteristics of each bus stop. All the data are transmitted to a server in real-time for storage and remote retrieval purposes. The surveyors are provided with unique login identities to improve the credibility of the survey. Every journey is labelled with a system-generated identifier which can be changed if necessary, to facilitate conducting surveys by placing two surveyors at the front and back doors of the same bus. On such occasions, retrieval of data can be carried out corresponding to the journey ID. Secondly, a handheld portable electronic device which is capable of locating its position at regular intervals was developed with single-board computers (e.g.: Raspberry Pi), GPS receivers, data communication module and rechargeable power sources. An interactive display similar to a mobile phone is available in this device. The surveyor can input the details about each journey before the departure. When the journey begins, the automatically recognized realtime GPS coordinates and travelling speed are displayed to the user. A single-click feature to log waypoints with an accuracy of 2.5m was also provided. This serves as a facility to locate bus stops, bottlenecks, intersections, or any other parameter as expected in the survey. These data are also sent to the same server and can be visualized through the front-end user interface. This approach can be directly utilized in assisting annual fare reviews incorporating both the cost component and income component eliminating past barriers. The data helps in developing driving cycles and thus fuel consumption and other cost parameters can be identified involved in bus services. The boarding and alighting surveys reflect the income components via the collected data. Thus, the calculation for fare review revisions become relevant and reliable with a good rationale and justifiable outcome helping three stakeholders (related authorities, passengers and bus owners/employees). This can be a fair play fare platform to all involved entities. The quality and level of service of public transit can be improved using this technological introduction including route requirements, increasing or decreasing supply as per the demand, improving and altering timetables (scheduling services) and restructuring bus stop locations and level of service of bus stops/terminals with available data based on demand and usage. The results that can be tabulated in terms of data via the ITS incorporated approach can be utilized for analysis with effective outcomes. It is very important to attain the quality of data along with a considerable quantity. This approach helps in establishing healthy quality data over the conventional methodology in Passenger Boarding and Alighting Surveys. The outcomes from analysis of the available data can be utilized with a higher acceptance in inclusion for required transportation applications. The data security and storage phases provide high effectiveness in comparison to conventional technology redundant approaches. A digital platform can facilitate easy quick data retrieval without having to waste considerable time and effort. In a sustainable perspective, the inclusion of technology into the surveys and its process helps in the reduction of waste and usage of resources increasing environmentally prominent actions in terms of the survey process and outcomes. This technique is deemed the way forward of surveys in transportation engineering since it has a low margin for error unless it is a technical malfunction. With the use of highly reliable and state of the art technology, better levels of precision and accuracy can increase the validity of decision making in the industry. This approach which is initially implied to be applied in public bus transport services can be extended to other public transit forms such as railways with minor parametric changes and can be developed further into a passenger transport analytics platform.
item: Conference-Abstract
Applying Built – Operate - Transfer (BOT) systems for Sri Lankan expressways: a case study
(Department of Civil Engineering, University of Moratuwa, 2020-12) Perera, AP; De Silva, D; Perera, HLK
Sri Lankan transport network had a massive development during the last decade experiencing highway infrastructure, with the utilization of foreign concessions and local government funds of the country. Road Development authority holds the pioneering authority to operate and maintain the highway and expressway network in periodically. The user benefits generated with the road network are travel time saving, developed infrastructure and living standards also with the social benefits which are not counter measured in quantitatively. As a developing country, a lack of financial stability for the infrastructure of the government may lead to foreign loans and concessions. The concessions lead to rapid involvement in the fund involvement for mega infrastructure projects as the necessity and demand of the country. The Build-Operate-Transfer (BOT) concession model is becoming a major trend in the privatization of infrastructure projects and the concession period and interest rate are critical parameters for BOT contracts. In this study, a model is developed to demonstrate the potentiality of applying BOT system for the expressway network of the country. The demand estimation, operation and maintenance cost and toll revenue used as the inputs for this model and financial viability is observed with different scenarios. The concession period, interest rates and optimality of selection of BOT are decided with different criteria based on financial viability. As the Colombo-Katunayaka Expressway (CKE) meets the highest demand for traffic in the expressway network, inputs of CKE used to demonstrate the potentiality of applying BOT model and optimum subsidy level was determined with the application of variable concession periods. This BOT model is further developed to validate any expressway network in urban or suburban basis by considering traffic demand with the considerations of unit length costs and revenues in operations with the performed analysis for existing and proposed expressways in Sri Lanka The urban and sub-urban links were defined for expressways, by considering the actual traffic demands between each intersection of Outer Circular Highway (OCH), Southern Expressway and forecasted traffic on ongoing Central Expressway and proposed Ruwanpura Expressway and costs and revenue per unit length were determined for each link in respectively by applying actual data.
item: Conference-Abstract
Assessing the walk-score of walking paths in Kandy City area for better walking experience for the tourists
(Department of Civil Engineering, University of Moratuwa, 2020-12) Wijeweera, KP; Dias, TWKIM; Perera, HLK
Walking has been always considered as a sustainable method of transportation which is more suitable for short-distance trips. The concept of “short distance trip” changes with the convenient maximum walking distance of a human being. However, it is observed that tourists would prefer to walk more than residents in cities with many tourist attractions located within close proximity. The City of Kandy, in Sri Lanka, can be recognized as one good example for such cities. Even though the tourists are willing to walk longer distances, this study has assessed the walking experience of a pedestrian in the city limits of Kandy, based on a walk score. Several walkability characteristics are taken into account to generate the walk score for segments of roads in the city and Pedestrian Level of Service (PLOS) was also considered. PLOS does not have considerations for tourists, it was used only to assess the basic requirements for pedestrians. A study done by Hall and Ram in 2018 comparing TripAdvisor ratings and Walk Score found that more specific assessments of walkability are required to evaluate the tourist requirements. Considering several works of literature as such, this study used an evaluation criterion developed by Dias in 2012 to obtain the walk-score and tourism specific features such as availability of shops and ATMs were taken into account. The objective of this study was to recognize the best walking paths between the tourist attractions using these qualities. The study area was based on the tourist attractions in Kandy and the importance of walking for the tourists within the city. Data were collected through field surveys in 2018 to identify walking facilities provided and to estimate PLOS in the selected street segments. Recommendations are proposed to improve the walking experience for the tourists. Twenty-six road segments were selected for the study and the Walk-score ranged from 24% to 60% with an average of 45% which cannot be considered as a satisfactory situation. As a walk score criteria were used, there was no requirement to do an opinion survey among tourists who walk these paths. Availability of amenities for pedestrians is one factor in estimating the walk-score in which the availability of bank facilities, restaurants, shopping malls, transportation terminals (bus stops and train stations), roadside benches etc. However, the results showed the lack of such amenities in many street segments which can be discouraging tourists to choose the street segment for their route. According to the results, it is important to remove obstructions which are located in the sides of the walkway which reduce the effective walkway width creating unnecessary queues. When selecting a walking path to reach a tourist destination it is expected that they will tend to select the best walking path. Using the results of this study, a tourist can take an informed decision on choosing the best route and also the relevant authorities can prioritize the budget allocations on improving roadside facilities.
item:
Axle load distribution characterization for mechanistic pavement design
(Department of Civil Engineering, University of Moratuwa, 2020-12) Sumanasekara, S; Mampearachchi, W; Perera, HLK
As per the World Bank records of the year 2018, Sri Lanka had the highest road density among the South Asian countries with 173.9 km of roads per 100 square kilometres of land. Sri Lankan government reserves a considerable amount of finance in every year for developing and maintaining the existing road infrastructure, which is a well-recognized national priority. Currently, in local road designs, the Overseas Road Note 31 and AASHTO method are the most frequently used design references. However, in these methods, the consideration given for utilization of readily available in-situ materials and incorporating characteristics of substandard materials into the designs is not significant. Therefore, in most of the occasions, the economics of the construction processes are adversely affected due to overdesigns. The AASHTO Mechanistic-Empirical (M-E) method of pavement design combines the physical causes such as stresses, strains, and deflections within a pavement structure and the empirical mathematical models. It also allows the designer to utilize in-situ materials and allows to optimize the pavement design to suit the conditions at the site. Although attempts had been made to adopt M-E design method in Sri Lanka, since the M-E design process requires a lot of data input, the preference of local practitioners in using the M-E method is not satisfactory. Out of the input parameters required for M-E design, traffic volume and axle load distribution data are crucial parameters. This study aimed at identifying trends in axle load group type distributions in different regions and to establish a classification for the pavement loading in regions throughout the island. It has been found that there are similar patterns in the distribution of axle group types throughout the island. Accordingly, on average the total axle counts in different regions constitutes of 57% single axles with single tires, 38% single axles with dual tires, 5% tandem axles with dual tires, and 0.1% tri axles with dual tires. Further, in this study, hierarchical clustering techniques have been utilized to identify geographical regions with similarities in pavement loading conditions. An attempt for zoning traffic load distributions for selected geographic areas has been presented in this study. Comparative for the resource utilization in obtaining axle load distributions, obtaining manual classified counts for a road is convenient. With the aid of the identified traffic load zones, this study will be useful for determining the traffic data input for M-E design, with a degree of accuracy level 2 as defined in the M-E design method.
item: Conference-Abstract
A data acquisition methodology for the development of local driving cycles
(Department of Civil Engineering, University of Moratuwa, 2020-12) Gajanayake, S; Bandara, S; Sugathapala, T; Perera, HLK
Driving Cycles (DCs), the time speed profiles of a certain vehicle type for a given road segment can be considered as one of the main tools to quantify and to assess the performance in terms of fuel economy and emissions of a given vehicle category. There have been numerous approaches that have been adopted to develop DCs locally, representing various geographical regions of the world. Despite various approaches adopted, the researchers have defined a four-stepped common methodology for DC development viz. Route Selection, Data Acquisition, Cycle Construction and Cycle Assessment. During the study, approaches have opted under each step pertaining to the purpose of the DC development, i.e. for the characterization of fuel economy. Acquisition of data for DC development is one of the most important steps of the procedure since the representativeness of the DC of local driving behaviour depends on the quality of the data collected. Regardless of the approach adopted, the acquired data should be reliable, representative, consistent and homogeneous. The three main approaches that are in practice throughout the world can be listed viz. chase-car method, instrumented-car method and hybrid method. During this study, more focus is concentrated on suggesting a methodology of data collection for DC development. Since local driving behaviour incorporates irregular kinematic patterns integrated with aggressive driving behaviour, the instrumented-car method has opted over the chase-car method. Moreover, the operational complexity and the cost associated with the latter approach is higher than that of the opted method. Furthermore, on par with the introduction of On-Board Diagnostics (OBD) protocol as a worldwide standard for automobiles in the later 1990s, the invention of many OBD data logging devices happened. Consequently, the data logging on an automobile has been made convenient than ever. When it’s funnelled down to the instrumented-car method, the techniques in practice can be listed under two main categories viz. device-based methods and device and app-based methods. In device-based methods, the data are saved in internal storage and then it’ll be transferred for analysis. On the other hand, the device and app-based method facilitate the real-time data to be transferred to the connected app-hosting device viz. a mobile device, tablet or a laptop. In the latter method, the data logging device is connected with the app-hosting device primarily via Bluetooth or WIFI. Car manufacturers have introduced their own OBD data logging devices with internal storage viz. Chrysler DRBIII, Ford New Generation Star Tester, General Motors Tech II, Toyota Diagnostic Tester, Nissan Consult, VAG 551, etc. The said devices have mostly been introduced with the manufacturers’ proprietary technology which has made them costlier. Due to the cost factor in the device-based method, most of the researchers have adopted device and app-based methods which have come up with low-cost alternatives. A dedicated data logging device, ELM-327 adapter has opted for the research study. Due to its lower cost and hence multiple devices can be used for parallel data collection in vehicles. Out of several third-party software applications for OBD data logging, Torque ProTM has been opted for the study mainly due to its feature-rich interface, operational convenience and compatibility with a wider range of vehicle variants. The data is sampled at a frequency of 1 Hz. The logged data onto the app-hosting device is saved in two main types i.e. ‘.csv’ file type and ‘.kml’ file type. The mechanical parameters viz. engine speed and fuel flow rate, the spatial parameters viz. latitude, longitude and altitude have been logged using the said device-app arrangement. During the study, data is planned to collect from two-wheelers (2W), three-wheelers (3W) and four-wheelers (4W). The initial phase of the study would be to analyze the data streams pertaining to 2W, 3W and 4W, then evaluate whether there are significant discrepancies among the driving behaviours and patterns. Then the second phase of data collection would be conducted to develop the local driving cycle. Unlikely in 4W, in 2W and 3W, an OBD port cannot be found in common. Thus, an app-based data acquisition method is recommended for 2W and 3W. With respect to this case, several readily available applications are tested. The major limitations of the applications are that they log data at lower frequencies such as less than 1 Hz and the operational difficulty of obtaining the logged data from the users’ devices since the real-time data logging feature is unavailable in most. Therefore, a locally developed application at the University of Moratuwa which suits the data collection requirements has opted. The sample size has been selected as thirty vehicles from each category, accounting for ninety vehicles altogether in all three types. The geography of data collection has been selected as the urban areas of Colombo City.
item: Conference-Abstract
Development of a 3D model of open-graded friction course to evaluate the inter-connected air void with aggregate gradation
(Department of Civil Engineering, University of Moratuwa, 2020-12) Dedigamuwa, KV; Mampearachchi, WK; Perera, HLK
Open-Graded Friction Course (OGFC) is an asphalt material which has many advantages such as resistance to hydroplaning, low level of splash and spray, less headlight glare, improved visibility, a lesser number of accidents, reduced noise, and higher surface friction. OGFC is an advanced asphalt material which cannot thoroughly be understood by the results of traditional tests available. Though, OGFC consists of mastic, aggregate and air voids similar to hot mix asphalt, the porous structure of OGFC consists of a highly complicated interconnected void network. The number of voids and the void area of OGFC directly affects the durability and the permeability of the mixture. Therefore, it is necessary to increase the ratio of the area of interconnected voids to the area of total voids, in order to enhance the permeability of the OGFC mixture. A digital image analysis method has been introduced in this research in order to obtain different interconnected void structures for different gradations. This method consists of the identification of different properties such as number of void nodes, number of interconnected voids, areas of interconnected voids, reduction of interconnectivity with the depth, etc. An algorithm in “MATLAB” was developed to identify the properties of the crosssectional images obtained by the captured surfaces of the cut specimens of OGFC. The obtained cross-sectional data of aggregates, voids and mastic was used to create the plotting data of the 3D model using the algorithm developed in excel. Finally, the python tool “plotly” was used on the “Anaconda” platform to create the 3D model based on the data model created in Excel. The data of three different gradations were analyzed by the use of this method and the results were obtained. According to the pre-evaluated test data of three gradations on durability and permeability, the validity of the 3D models was analyzed. The developed 3D model from this study can be used to determine the optimum gradations of OGFC considering the durability and permeability, based on the analysis of the internal structure arrangement.
item: Conference-Abstract
Development of fine aggregate using coal fly ash with internal curing characteristics
(Department of Civil Engineering, University of Moratuwa, 2020-12) Tharshigan, T; Pradeep, I; Mampearachchi, WK; Perera, HLK
Fly ash is produced as a byproduct from Lakvijaya coal power plant, Norochcholai, Sri Lanka. The daily production of fly ash at Lakvijaya power plant is 950 – 1000 tons. Some part (around 40%) of fly ash is consumed by cement manufacturers, the balance of fly ash is stored without any means of disposal inside the plant. This research study discusses the development of fine aggregate replacement material using sintered coal fly ash with internal curing characteristics. A series of samples were prepared with different composition of fly ash and reservoir sediment material and sintered from 8000C to 13000C temperatures in the interval of 1000C for 30 minutes of sintering time then crushed to prepare fine aggregates. Here reservoir sediment material was used as a binder material and it improved green strength of solidified fly ash. TGA – DSC and XRF analysis was used to investigate the thermal and chemical properties of raw materials, respectively. The microstructure of produced fly ash aggregate was observed using SEM photographs. Water absorption, water desorption and relative density of fine aggregate were measured. Water absorption and relative density aggregates were the range of 21 – 40%, 1.2 – 1.55, respectively. The aggregate with 80% of fly ash and 20% of reservoir sediment material which heated at 11000C had 21.4% water absorption and 74.12% water desorption was selected as suitable replacement material instead of natural river sand. concrete was prepared using wetted fly ash aggregate by replacing 23.5% of natural river sand and external curing has not been done for that concrete. Concrete with wetted fly ash aggregate achieved lower strength at an early stage then after 28 days, it achieved more strength than conventional concrete. Fly ash aggregate supplied internally stored water for hydration reaction of cement after finish the free water present inside the concrete and gave internal curing behavior to the concrete therefore concrete with fly ash aggregate gained more strength than conventional concrete without external curing.
item: Conference-Abstract
Development of performance indicators to evaluate performance-based road maintenance contracts
(Department of Civil Engineering, University of Moratuwa, 2020-12) Mullevithana, GL; Bandara, JMSJ; Perera, HLK
Effective maintenance is essential to achieving sustainable development in Road sector. There are categories of maintenance activities as per the time of attendance, the period of attendance and frequency of attendance. Period for relevant activities is not specific. It is varying with the site condition and various parameters. Build- up the relationship between parameters helps to deliver the tangible results to programming, scheduling and budgeting for good governance, accountability and transparency in performance base maintenance. Road maintenance activities can be classified as per nature of attending; Routine, Recurrent, Periodic and urgent. Indicators of Road Surfacing and Road Marking on the paved road under periodic maintenance were selected to monitor and evaluation in this study. These activities are required to attend at periods of several years, the frequency depending on the damage caused by traffic and other factors. International Roughness Index (IRI) of road surface data was collected by the existing RDA database and Roadroid Mobile App with comparing last improvement details on selected road segments. Data for thickness, skid resistance and reflectivity of road marking were collected by the field test with following the tools of monitoring and evaluation (M & E) which can be used to improve the way achieving better result. Collected data were analyzed using panel regression, multiple regression and logistic regression tools. Initially stationary of data that represent variance and autocorrelation structure do not change over time was tested according to the Hadri Z statistic and results are significant providing selected stationary data. Out of random and fixed effect models, the most appropriate model is recommended by the Hausman test and that is the random effect model. According to this model, IRI gradually goes up due to Annual Average Daily Traffic (AADT) and within the periods, IRI will come to the critical level where the roads must be paid attention for the development. The range needs to be provided for periodically with achieving a critical range of IRI using selected stationary data models. Relationship between thickness, skid resistance & reflectivity of road marking with ageing is to be built up for future implementation and continue appropriate maintenance strategies.
item: Conference-Abstract
Effect of blending temperature and blending duration on the degree of blending of reclaimed asphalt binders
(Department of Civil Engineering, University of Moratuwa, 2020-12) Hettiarachchi, C; Hou, X; Xiang, Q; Yong, D; Xiao, F; Perera, HLK
Recycled asphalt mixtures are getting more popular due to many economic and environmental benefits such as a higher degree of recyclability, low material cost, less effect on the environment etc. Typically, reclaimed asphalt pavement (RAP) materials are combined with virgin aggregates and virgin asphalt binder to produce recycled asphalt mixtures. The amount of RAP binder mobilizes into the mixture is called the degree of blending. The degree of blending of reclaimed asphalt pavement (RAP) binder is strongly influencing the performance of recycled asphalt mixtures. If the degree of blending is known, the asphalt mix designers can make better decisions during the mix design process to produce more durable recycled asphalt mixtures. If the degree of blending is overestimated, the mixture could have less amount of binder. On the other hand, underestimating the degree of blending could produce mixtures with higher binder content. Hence, it is very important to properly determine the degree of blending of RAP binder. However, understanding the factors affecting the degree of blending and quantifying the degree of blending is still an open problem for researchers. This study investigates the effect of several factors such as blending method, blending temperature, blending duration, and RAP content on the degree of blending using Fourier Transform Infrared Spectroscopy (FTIR) analysis of the extracted binder from mixtures. It is revealed that the blending method, blending temperature, and blending duration have a significant influence on the degree of blending. The study revealed that prolonged blending durations and elevated mixing temperatures could improve the degree of blending. The amount of RAP in the mixture has little or no influence on the degree of blending. Further, based on the results, a blending chart is developed to determine the degree of blending with regard to blending duration and blending temperature.
item: Conference-Abstract
Effect of crash barriers on driver behaviour
(Department of Civil Engineering, University of Moratuwa, Sri Lanka., 2020-12) Rajapaksha, S; Wickramasinghe, V; Perera, HLK
Crash barriers are widely used in mountainous roads with having open road sections. Crash barriers are often defined as safety barriers due to the positive safety impacts achieved. The current study is having the aim of checking whether there exists any relationship between the behaviour of the drivers with the presence of crash barriers. Here, the speed and lateral displacement of the vehicle are considered as driver behaviour. Class “A” road having consecutive similar radii bends with and without the presence of crash barriers was selected. The selected crash barrier was a Steel-type W-Guardrail crash barrier with having a height of 1.5m and a length of 50m in total. Data collection was done on a weekday from 4.00 pm to 6.00 pm using a drone and three cameras. Video footage data was extracted using tracking software. Speed and lateral position of each vehicle were collected at 5m apart along the curve. For the analysis, the average speed and lateral displacement values of each vehicle were used. The same data extraction procedure was adopted for both curves. Totally 180 number of vehicles were collected. As the primary objective, a hypothesis test was done to determine the effect of crash barriers towards the vehicle speed and the vehicle lateral position. According to the 2-tailed t-test results, obtained p-value <0.05 and hence, the null hypothesis is rejected. This implies that the existence of a crash barrier significantly effects for the vehicular speed and lateral displacement.
item: Conference-Abstract
Effect of crowding cost on optimized headway of an urban bus route
(Department of Civil Engineering, University of Moratuwa, 2020-12) Devasurendra, KW; Wirasinghe, SC; Kattan, L; Perera, HLK
Discomfort due to crowding in transit is a significant factor driving public transport mode choice. However, few studies account for passenger cost due to crowding in transit as an integral part of planning transit operations. This study explores the optimized headway operations of an urban bus line with attention to crowding costs. An analytical expression for the cost of crowding discomfort of passengers is developed. The cost of crowding discomfort is accounted for by penalizing the average value of riding time (VoRT) of passengers. Accordingly, VoRT is multiplied by a crowding penalty factor (CPF). CPF is formulated as a function of the load factor (L) that represents the crowding level inside the bus. This expression is integrated into an objective function that is the summation of operator and user costs, building on the square root dispatching policy developed by Newell (1971) and extended to ‘many to many’ demands by Wirasinghe (1990). The objective function is then optimized in terms of headway to obtain the value that minimizes the sum of passenger and operator costs. It is found that, in the presence of crowding costs, the optimum headway is smaller, and depends on bus size, the mean value of riding time, average trip time in the bus route, and the functional form of CPF. The scope of crowding cost on optimized headway is shown using an example.
item: Conference-Abstract
Effectiveness of demolished concrete waste for resurfacing of low volume roads in Sri Lanka using roller compacted concrete (RCC) technology
(Department of Civil Engineering, University of Moratuwa, 2020-12) Jayantha, WRAN; Mampearachchi, WK; Perera, HLK
Roller Compacted Concrete Pavement (RCCP) is a type of zero slump concrete product, which has renewed the interests of sustainable pavement designers with its potential to reduce the total cementitious material content of the concrete mix. RCC is produced with the same ingredients as in conventional concrete paving, but with different proportions determined by a suitable mix design approach. RCCP construction procedure is similar to that of asphalt paving, where laying is performed using a modified asphalt paver and steel drum rollers follow the paver to ensure laid RCC mix to be compacted to its desired density. However, in low volume road construction, motor graders can be used in place of modified asphalt pavers for the laying process since the degree of precision required is low. Even though concrete pavements are durable in the norm, owing to poor construction practices and improper maintenance, the concrete surfacing of low volume roads is at a stage in need of rehabilitation. The current rehabilitation practice of the damaged concrete roads in Sri Lanka is replacing the damaged pavement with a new surfacing, where the deteriorated concrete layer is removed as a landfill material or sometimes reused as a base for the new surfacing. However, full disposal of the damaged pavement and subsequent replacement with a new pavement is not an economically viable construction practice. The objective of this research is to evaluate the applicability of deteriorated concrete pavement for the reconstruction of new pavement in an economical and sustainable approach. In this study, manually crushed concrete slabs were washed, sieved, and tested for aggregate strength to be used as a substitution of coarse aggregates (CA) in RCC. Control samples were cast with the use of virgin crushed aggregates (VCA) and test specimens were prepared with recycled concrete coarse aggregates (RCCA) in full replacement of CA. The mix proportions of the concrete mix were calculated using the soil compaction method, which focuses on the optimization of the dry density of the RCC mix. Vibratory hammer test – ASTM D7382 (VHT) was used in place of the modified proctor test – ASTM D1557 (MPT) in determining the optimum moisture content (OMC) of RCC concrete since an impact compaction test does not exactly simulate the actual site condition at the mix design stage. The dry density of RCC test specimens was found to be very sensitive to moisture content when the compaction was coupled with vibration. VHT resulted in higher density and lower OMC while MPT produced almost the same density at a higher OMC. However, the actual site compaction practice involves a combined effect of vibration and impacts. A compressive strength over 20MPa can be easily achieved for RCC, even with full replacement of CA with RCCA. Therefore, the importance of incorporation of the VHT in the mix design process and the possibility of full replacement of CA of RCC by RCCA, are elaborated in this research.
item: Conference-Abstract
Enabling ITS applications with affordable communication technologies
(Department of Civil Engineering, University of Moratuwa, 2020-12) Wickramarachchi, T; Dharmaraj, N; Malinda, D; Nettasinghe, G; Senevirathne, I; Weerasuriya, S; Dias, D; Samarasinghe, T; Hemachandra, K; Perera, HLK
Intelligent Transport System (ITS) aims to make travel and transportation safer, faster and more efficient. ITS includes but is not limited to emergency services, road safety, transportation infrastructure, traffic management as well as commercial and infotainment applications. This paper experimentally investigates the feasibility of using low-cost wireless technologies as an enabler for introducing ITS to Sri Lanka. We interpret our results with relevance to two ITS applications. With the growing vehicular traffic in the country, the need for ITS applications has become imperative. For instance, while the current manual highway toll collection is ineffective during traffic peaks, the electronic version causes delays and congestion due to its stop-and-go process. Poor control of level crossings has become a major cause of fatal accidents. Road signs are often unnoticed or are deliberately ignored by drivers and dynamic road situations such as pedestrians, constructions, landslides, etc., will make the driver indecisive until alerted. Dedicated Short-Range Communication (DSRC) is a standardized wireless technology for ITS, with its reliable operation in dense, high-speed vehicular environments. However, the high cost of the technology has restrained its penetration in the automobile industry and adoption by governments. DSRC is based on the IEEE802.11p standard. The IEEE802.11 family of standards also defines versions b, g, and n, better known as WiFi. The common root makes it possible to use WiFi which facilitates a subset of ITS applications with a significantly lower cost. Several types of wireless links are fundamental to ITSs; between vehicles (mobile to mobile), between vehicles and roadside infrastructure (mobile to fixed), infrastructure to vehicles (fixed to mobile) and between infrastructure nodes (fixed to fixed). ITS applications rely on regular exchange of information (location, speed, bearing etc. or event-driven information such as the presence of a pedestrian) among vehicles in the neighbourhood via broadcast messages (data packets). Factors that influence the performance of the applications include packet loss, packet delay and communication range. This paper presents the experimental evaluation of fixed-tofixed and fixed-to-mobile communications links established via WiFi. We study the packet loss, delay and the communication range in each case. We then discuss the applicability of the results in relation to the following ITS applications: ● An Active Road Sign system which allows for messages to be relayed to drivers in the vicinity. Our results show that such messages can be received reliably over a range of 150m. ● A railway intersection warning system which allows warnings of approaching trains to be delivered to vehicles approaching the intersection. We demonstrate that vehicles within 200m distance of the intersection can be warned when the approaching train is 700m away. Further, our design achieves an end-to-end delay less than 100ms, satisfying the criteria stipulated for safety-related ITS applications. Furthermore, our system allows the warning messages to be conveyed via audio-visual means, with the intensity proportional to the level of attention required by the driver.
item: Conference-Abstract
Estimating the follower vehicle platoon delay due to “U” turn vehicles at centre median openings
(Department of Civil Engineering, University of Moratuwa, 2020-12) Abeygunawardana, C; Wickramasinghe, V; Perera, HLK
U-turn vehicles at centre median openings create queues while waiting for acceptable gaps. This phenomenon creates delays for the follower vehicle platoon. The current study aims to estimate the delay for the follower vehicle platoon due to U-turn vehicles at centre median openings. This study considered the movement of the U-turn vehicles at the centre median opening at Dehiwala, Sri Lanka. The road stretch considers here is operated as a two-lane divided dual carriageway. Data were extracted from video footage done on a weekday for six hours in a heterogeneous traffic condition. Here more attention was paid to select the U-turn vehicles when the near lane is having continuous vehicle flow. This makes the follower vehicles to wait in a platoon until the U-turn vehicle takes the gap. When other vehicles passed awaiting U-turn vehicle, that U-turn vehicle was not considered for the calculations. The average waiting times (critical gaps) of different U-turn vehicle types were calculated. Those critical gap values are 14.5, 10.5, 9.2, and 8.2 seconds for heavy vehicles, cars/vans/jeep, bikes, and three-wheelers respectively. Data were analyzed using ‘Queue Theory’. The M/M/1 queuing system that refers to ‘arrival rate (𝜆 )’ and ‘discharge rate (𝜇 )’ with a single lane queuing system was selected. Delay was calculated for the complete follower vehicle platoon due to U-turn vehicle. Using arrival rate (𝜆 ) and discharge rate (𝜇 ) to the equation of queue theory 𝜆 / 𝜇 ( 𝜇 − 𝜆 ), ‘delay for the follower vehicle platoon’ was found. For a stable system, discharge rate (μ) should exceed arrival rate (λ) and here that requirement was fulfilled. U-turn three-wheelers created the highest platoon delay and the average time of delay created by three-wheelers is 70.6 seconds. Here λ and μ also depended on the traffic condition of both ‘opposite’ and ‘same direction’ of U-turn vehicle. Because of that reason, not only the ‘type’ of U-turn vehicle but also the traffic condition of both direction affects the delay caused by each U-turn vehicle. The vehicle type that more likely to make U-turn is ‘three-wheeler’. Further, ‘delay cost’ for the follower vehicle platoon due to each type of U-turn vehicle was found by using the average value of time of a person. Calculating the delay cost for each follower vehicle platoon depended on the different vehicle types in that platoon during the waiting time of that U-turn vehicle. When the U-turn vehicle was a van, the delay cost for the follower vehicle platoon was rupees 10.93. It is the maximum delay cost. The delay cost created by other different U-turn vehicles were rupees 9.05, 7.85, 7.75 and 7.55 from a car, light goods vehicle, three-wheeler and bike, respectively. The results from this study can be further extended to optimize the number of centre median opening for U-turns mainly in arterial roads.
item: Conference-Abstract
Evaluation of aircraft excursion risk at Bandaranaike International Airport
(Department of Civil Engineering, University of Moratuwa, 2020-12) Galagedera, S; Pasindu, HR; Adikarivattage, V; Perera, HLK
Though Safety is one of the top priorities in the aviation industry, according to the IATA statistics (2020), all accident rate in 2019 was 1.13 per million flights. Among the aircraft accidents, the majority of aircraft accidents take place at airports and airport near vicinity areas. Considering the airport-related accidents, a high proportion of aircraft accidents have occurred during the landing and takeoff phases which are altogether only 1% of the whole flight time of 1.5-hours flight duration. Aircraft excursions and incursions are the two key types of accidents at runways. With regard to runway excursions, landing, and takeoff overruns, veer-offs and landing undershoots are common aircraft accident types. As IATA figures, there were 17 runway excursions (32% out of total aircraft accidents) in 2019 and it was identified as an area where further improvements need. These excursion accidents can take place at any runway facility depends on the aircraft and airport operational and design factors. Thus, risk analysis which assesses potential event probabilities is a vital component in aviation risk management. Quantitative approaches such as risk models and qualitative approaches such as risk matrix, expert opinions, etc. are commonly used in risk assessments. Accordingly, under the Airport Cooperative Research Program (ACRP), Transport Research Board (TRB) developed models for overrun, veer-off, and undershoot probability estimation at landing and takeoff operations. Thus, excursion risk at distinct operational and weather conditions can be estimated along with these event probabilities and the corresponding severities. Referring to Runway Protection Zones (RPZs) Risk Assessment Tool developed in ACRP 168 by Shirazi et al. (2016), this paper estimated landing overrun risk for 4E category B747-400 aircraft (critical aircraft for BIA) at various operational conditions at Bandaranaike International airport (BIA). The model developed by Ayres et al. (2014) was used to analyze landing veer-off risk. Those estimated landing overrun and veer-off risks were compared with regard to the risk at 30o C ambient temperature. Accordingly, the corresponding overrun risk increase by 27 times at tailwinds 12 knots or above. Similarly, when it rains, the above estimated overrun risk will increase about 5 times. Further, the corresponding veer-off risk increase approximately 10 times when crosswinds above 12 knots. Considering the sensitivity of various weather factors, the impact of fog, visibility, rain, and tailwinds gradually increase on landing overrun risk. In the BIA context, a condition at which tailwinds 12 knots with rain and reduced visibility will be the worst weather conditions on landing overrun risk. Thus, excursion risks vary at different operational and weather conditions. Additionally, this research emphasizes the importance of runway design elements such as runway length, runway shoulders, airfield safety areas such as Runway End Safety Area, Object Free Area, and arresting systems such as Engineered Material Arresting System, etc. These elements can minimize potential excursion risk by minimizing corresponding event probabilities or respective severities. Accordingly, airfield design elements play a vital role in minimizing and maintaining aircraft excursion risks at a universally accepted target level of safety indeed 10-8 for a landing mission.
item: Conference-Abstract
Evaluation of criteria for setting speed limits to Sri Lankan highways (built-up areas)
(Department of Civil Engineering, University of Moratuwa, 2020-12) Silva, N; Kumarage, H; Guruge, M; Wickramasinghe, V; Perera, HLK
The speeds of vehicles are the most pivotal factor in most road traffic accidents. Enforcing a suitable speed limit is a tool for enhancing road safety. However, the currently available posted speed limits are placed without much scientific investigation. Those limits are merely decided by selecting a vehicle category. According to the Gazette of the Demographic Socialist Republic of Sri Lanka, No.1763/26, June 22, 2012, it was divided all vehicles into two vehicle categories and proposed only two-speed limits for the built-up areas. Such as 40 km/h for motor tricycles, special purpose vehicles, and 50km/h for all other vehicles. However, it is understood that road geometry, roadside environment, vehicle density, accident rates, average daily traffic values, etc, should be considered. The current study is having the aim of investigating the influence of such factors on speed limits. For that, ten site locations with different geometric characteristics, vehicle composition, and accident rates were selected in built-up areas. Using speed guns, the speeds of randomly selected vehicles were recorded. Totally, 3000 vehicle speeds were collected. Initially, vehicles were divided into four categories as motor-bikes, three-wheelers, light vehicles, and heavy vehicles and performed ANOVA to find out whether there exists any difference in 85th percentile speed value between each vehicle category. The intention was to group the vehicles into similar speed clusters. It was identified that motor-bikes and light vehicles like Car/ Van/ Jeep are be selected as one cluster while three-wheeler and heavy vehicles like Buses/ Light good vehicles/ Heavy good vehicles as the other clusters. Next, in order to identify the influential factors towards the speed limit of each cluster, a correlation with each factor for the speed was observed. From the results, the speed limit of motor-bikes, three-wheelers, and light vehicles are heavily correlated with factors such as lane width, bicycle lane width, shoulder width, parking width, and the road markings, whereas the speed limit of heavy vehicle category is greatly correlated with the one-way or two-way operation and the roadside activity apart from the above factors. Finally, a multiple linear regression model for each vehicle cluster was fitted and validated. The most influential factor in deciding the speed limit is the availability of bicycle lane irrespective of the vehicle cluster. Besides, not only for heavy vehicles but also three-wheelers and light vehicles, the roadside activities are also negatively contributed to deciding the speed limit. These developed models are useful to review the existing posted speed limits in built-up areas.
item: Conference-Abstract
Evaluation of criteria for setting speed limits to sri lankan highways (non-built-up areas)
(Department of Civil Engineering, University of Moratuwa, Sri Lanka., 2020-12) Kumarage, H; Silva, N; Guruge, ML; Wickramasinghe, V; Perera, HLK
Speed limits are posted on roads to enhance the safety of road users. However, no comprehensive norm is adhered in deciding the speed limits in many countries, and Sri Lanka is not an exception. In Sri Lanka, the speed limit is solely decided by the vehicle category and location (i.e., whether the road is located in a built-up area or non-built-up area). No geometric features of the roadway, roadside environment or safety concerns are been considered. Thus, this research is having the aim of investigating the factors to be considered in deciding the speed limits for roads in non-built-up areas. In that context, data were collected in ten locations located in non-built-up areas. At least 300 data samples were obtained from each selected location. Those ten locations were selected based on different geometrical characteristics, roadway environment, vehicle density, accident rates, and road classes. Initially, the ANOVA test was performed to find out whether there exists any difference in 85th percentile speed value between vehicle categories. The intention was to divide the vehicles into similar speed clusters. From that, it was identified that motor-bikes and light vehicles are selected as one cluster while three-wheelers and heavy vehicles as another cluster. Next, to identify the influential factors towards the speed limit of each cluster, correlation matrices were observed. From the results, the speed limit of motor-bikes is highly correlated with the roadside activities, roadway operation (one-way or two-way) and roadway marking. The speed limit for three-wheelers and light vehicles are mainly influenced by lane width, roadway operation (one-way or two-way), roadside activities and road markings. Roadside activities, lane width, roadway operation (oneway or two-way) and bicycle lane width are the factors affecting the speed limit of heavy vehicles. Multiple linear regression models were fitted for each vehicle cluster and validated. Mainly roadside activities, lane width, roadway operation, and road markings are collectively affected in deciding the speed limits. These developed models are useful in review the existing posted speed limits in non-built up areas.
item: Conference-Abstract
Experience in calibrating the VISSIM microscopic simulation model for a signalized intersection
(Department of Civil Engineering, University of Moratuwa, 2020-12) Gunathne, D; Amarasingha, N; Wickramasighe, V; Kulathunga, A.; Perera, HLK
Traffic microsimulation software is a traffic management tool which is currently being used in various countries to provide traffic management solutions. For developing countries like Sri Lanka, it is possible to observe a mixed heterogeneous traffic condition which includes lack of lane discipline, lack of lane marking, etc. The calibration process should be done before using the microsimulation software for local conditions in those countries to make the model results reliable and accurate and after the validation process, it is possible in simulating traffic management solutions. The main objective of this research study is to calibrate the VISSIM software for heterogeneous local traffic condition as the software is originally developed for homogeneous traffic conditions. VISSIM models which were calibrated previously for Sri Lankan traffic conditions are available and initially, the validity of some those models was tested. However, the simulated results of those models did not give the actual traffic characteristics in the study area. Also, in the VISSIM models calibrated previously in Sri Lanka, the driver behaviour parameter values were randomly selected and tested them on the VISSIM, but in this study, the calibration of driver behaviour parameters was done minimizing the simulation error percentage using a Genetic Algorithm (GA). The GA was used rather than randomly selecting the parameter values as it will provide with higher accuracy of the optimum values of the driver behaviour parameters and also it is fast compared to selecting the parameters randomly. The calibration was done in a signalized intersection focusing the driver behaviour parameters. Ten most sensitive driver behaviour parameters were identified through literature survey which is looking ahead distance, look back distance, average standstill distance, additive part of safety distance, multiplicative part of safety distance, distance driving, distance standing, minimum headway, waiting time before diffusion and safety distance reduction factor. The model was done for the Malabe three-legged signalized intersection and the average queue length was considered as the Measure of Effectiveness (MOE). Queue lengths were measured by using 5m marking tapes which were placed at 5m intervals in all the legs of the intersection. The data were input to the VISSIM software including the road geometry, and the signal timings related variables which measured at the intersection. The traffic volume and vehicle composition at each leg was recorded using video cameras and the videos were analyzed manually to gather the required data. The intersection was modelled in VISSIM software and the mean absolute percentage error (MAPE) for the intersection was calculated by using the observed average queue length and the simulated queue length. For that GA optimization was done using the MATLAB GA Toolbox for the fitness function developed based on the percentage error, between the observed and simulated average queue length, under different driver behaviour parameters. The maximum value for MAPE was considered as 15% as recommended by literature. In future, the calibrated parameter set will be validated with similar intersections and it will be used for simulations of traffic in the area.
item: Conference-Abstract
Feasibility study of using calicut tile waste as an internal curing fine aggregate in construction industry
(Department of Civil Engineering, University of Moratuwa, 2020-12) Pradeep, KI; Tharshigan, T; Mampearachchi, WK; Perera, HLK
Over recent decades, internal curing concept has become emerging technology and research in this area has increased tremendously. American Concrete Institute described internal curing as “a process by which the hydration of cement continues because of the availability of internal water that is not part of the mixing water”. Internal curing facilitates to minimize autogenous shrinkage as water in the pore structure will work to fill pores which lead to shrinkage. And also, effective cement hydration process will perform inside concrete by maintaining internal relative humidity which leads in to avoid self-desiccation. Over the years, various methods and materials have tested to use as an internal curing aggregate. Calicut tile waste is generated as a wastage (damage tiles) in manufacturing factories and as construction and demolition waste in the construction industry. Waste Calicut tiles cannot be re-used to cast tiles as it is no longer shows clay properties with the phase changed of the material. The development of an internal curing fine aggregates using Calicut tile waste is described in the study. The internal curing fine aggregates are prepared by crushing Calicut tile waste to the size less than 4.75mm. Then crushed calicut tile chips are soaked in water for 48hours to absorb and retain water inside the microstructure. Water absorption, Water desorption, the relative density of pre-wetted Calicut tile chips and microstructure were studied. According to ASTM C1761M, internal curing aggregate shall have a 72-h absorption not less than 5%., the release of at least 85% of its absorbed water at 94% relative humidity. Water absorption of 23%, water desorption of 91% and a relative density of 1.8 showed in the investigations. Scanning electron micrographs images of the aggregate show that tiny pores (> 100nm) are presented in the microstructure which can store water and release for hydration. Initial investigations revealed that Calicut tile waste can be used as an internal curing fine aggregate since it has the required water absorption and desorption capacity.

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