Master of Engineering in Highway & Traffic Engineering

Permanent URI for this collectionhttp://192.248.9.226/handle/123/37

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item: Thesis-Abstract
Framework to incorporate safety performance in highway asset management system-case study on provincial roads
(2023) Tharmarajah, S; Pasindu, HR
According to the functional and management obligations, the road network in Sri Lanka is classified into national, provincial, and local authority roadways. Provincial roads in Sri Lanka are considered class C and D, which serve as connections between urban and rural areas to ensure social and economic necessities. Even though it is a developing country, the majority of these roads are in poor condition, and safety concerns are minimal. The lack of accurate accident data and a road condition monitoring program are frequently mentioned factors. This study proposes a methodology to determine a safety index to evaluate safety performance on provincial roads in Sri Lanka with the maintenance scheme using an optimization approach. A cumulative safety index (CSI) is computed with fundamental elements such as exposure, probability, and consequences. The Computed Cumulative Safety Index (CSI) is validated using available crash data. All severity levels in the crash data, such as fetal, grievous, and non-grievous, are translated to a single scale termed Equivalent Property Damage Only (EPDO) to validate the results. Once the actual EPDO is calculated, a multiple regression analysis tools is used to determine the relationship between the actual EPDO and a computed CSI composed of identified safety issues in the road segments. Actual EPDO and estimated EPDO were compared using Root Mean Square Error (RMSE). Safety treatments are implemented for the identified safety issues at the given location. All of the safety treatments are unable to be implemented in the area due to a lack of funds. A framework is proposed to include safety performance in the Highway Asset Management System, particularly in the optimization analysis, which comprises the objective of minimum average network CSI. The results from the study show that roads with safety concerns are prioritized in budget allocation with a feasible combination of safety treatments. This methodology provides a crucial analytical tool to the Highway Management System, which simplifies the process of including road safety performance in provincial road network management. Key words: Provincial roads, Safety Index, Cumulative Safety Index, EPDO, Optimization
item: Thesis-Abstract
Evalaute vehicle operating cost by vehicle categories
(2024) Ellegama, EGHDB; De Silva, GLDI
The transportation demand has been increasing and the planners and engineers have been trying to find the best solutions to overcome this problem. The cost of travel plays a major role in one’s decision to select the transport mode in their day-to-day transportation decisions. Although travel time is considered the main attribute in their decision-making, the cost of using a vehicle is also considered as an important attribute. Therefore, the vehicle operating cost (VOC) is considered a vital piece of information that is frequently used in transport planning, mainly in demand model estimations and economic feasibility studies. VOC can be separated as a fixed cost and variable cost based on what the cost being accounted for. Fixed cost is the component paid periodically, yearly, irrespective of the vehicle is used or not. The licensee fees, insurance fees, and gas emission fees are examples of fixed variable costs. On the other hand, variable costs, are the cost components that add up with the distance of travel. The fuel cost, tire cost, maintenance cost, and labor cost are examples of variable costs that are commonly considered. Vehicle type and its conditions can influence operating cost variables, where the vehicle condition can be identified according to the model year and the registered year of the vehicle. Road condition, travel speed, and road geometry are among other factors that can contribute to vehicle operating costs. The VOC is unique to each country and understanding the vehicle operating cost and estimating it based on statistical methods for Sri Lanka was the objective of this research. The study looked at collecting data through data loggers of several vehicle categories over 1-year period. The data included fuel consumption cost, tire cost, maintenance cost, service cost, insurance & permit cost. The data was collected mainly for motorcycles, double cabs, and private cars, The study was able to establish the VOC for the main vehicle categories expressed as a cost per km traveled and the study also established the variation of the operating cost as a function of the total distance traveled over one calendar year. According to the data analysis data in 2019, Y= aX-b + c type interpolation gives the best-fitted line for the relationship between VOC per km (X) and travel distance in kilometer(Y). Keywords: Vehicle Operating Cost, Fixed Cost, Variable Cost
item: Thesis-Abstract
Review of decade of action in road safety : trends in vulnerable road user crashes in Sri Lanka
(2023) Fernando, MSU; Pasindu, HR
Vulnerable road users (VRUs), including pedestrians, cyclists, motor cyclists, and three-wheeler users, account for a significant proportion of global traffic fatalities, particularly in low-middle-income countries. In Sri Lanka, VRU-related fatalities constitute more than fifty percent of all road crash deaths. This study aims to examine the trends and factors influencing VRU crashes and fatalities during the decade of action (2011-2020), considering changes in motorization, demographics, and economic factors while accounting for the impacts of the Easter attack and the COVID-19 pandemic. Data from 2010 to 2020 were analysed, with the exclusion of 2020 data due to the influence of COVID-19 on travel behavior. The relationship between economic and social factors was examined using Pearson Correlation and Granger Causality Tests, while the significance of the trends was assessed using the ANOVA Test. To ensure the accuracy of the trend, two statistical methods, Mann-Kendall, and Innovative Trend Analysis, were utilized for further trend analysis and comparison. The findings reveal that VRU-related fatalities comprised 87% of total road crash fatalities in Sri Lanka from 2010 to 2020. On average, there were 6.57 VRU fatalities per day, resulting in an average death rate of 11.38 per 100,000 population per year between 2010 and 2019. The analysis also indicates a strong correlation between new motor cycle registration levels and VRU involvement in road crashes. VRU involvement, VRU fatalities, VRU motor cycle crashes, motor cycle fatalities, three-wheeler crashes, three-wheeler fatalities, pedestrian crashes, and pedestrian fatalities exhibited a statistically significant increasing trend from 2010 to 2019. Conversely, bicycle crashes displayed a statistically significant decreasing trend. Pedestrian crashes, while statistically significant, did not demonstrate a trend. These findings underscore the urgent need for targeted road safety measures to address the identified issues. Efforts should prioritize improving safety for all VRUs and reducing the number of crashes and fatalities on Sri Lankan roads.
item: Thesis-Abstract
Review of the road sector investments in the last decade : its economic impact and sustainability
(2023) De Silva, MJ; Pasindu, HR; Bandara, YMMS
The Sri Lankan government allocates a significant amount of its yearly capital expenditure toward road infrastructure projects. Since the end of the war terror in 2009, the Road Development Authority (RDA) has invested around 6% of the government's total construction budget for road projects. A significant proportion of financial resources voted for Provincial Councils, and nearly one-third of what RDA obtains has been committed to road infrastructure expansion. When assessing the economic feasibility of a particular road section, a threshold Project Impact Rate of Return, EIRR (Economic Internal Rate of Return), of 9%-12% is typically used. Given the country's GDP (Gross Domestic Rate), this would be a substantial amount of money for a developing country like Sri Lanka. So, determining how effectively capital funds are provided in contrast with the benefit utilization is critical for a sustainable economy. Moreover, the per capita expenditure under transport administrative overheads is drastically high in the country, creating an unsustainable expenditure for the government of Sri Lanka with a fragmented setup in road construction. This study shows whether these road investments have effectively materialized in the last decade toward the country’s sustainable economic growth. The data collection for the study was done through primary and secondary data collections mainly focusing on RDA, PRDA, and rural road projects. In the methodological approach, the performance of road sector investments over the previous decade was analyzed with an emphasis on how money was transferred for road network construction. Identification of how total investments were aggregated across multiple state agencies in Sri Lanka was carried out along with a multi-year benefit calculation in comparison with VOT (Value of Time), VOC (Saving on Vehicle Operating Cost), and Accident Cost Saving. Funding patterns and scenarios were established while investment distribution by province, road class, and geographic locations was considered to compare the GDP growth rate of each province and subsequently to identify growth potentials in respective areas. The calculation was done considering the total expenditures where all these projects would have been feasible under a Minimum EIRR of 9-12%. The study determined whether these projects could provide the expected benefits for the country and if it is reflected in the natural GDP Growth rate. The Macro-Economic approach of the Harrod–Domar (HD) Model of Economic Growth and Development Theory was applied to this concern. Iv Descriptive statistics were carried out in the context of project EIRRs, financial investments, NPV, road length, and road class wise, and subsequently, several relationships were developed. The findings revealed that predicted benefits in the road sector over the previous decade have been overstated since the underlying assumption of estimated economic benefits, that would convert into economically productive activities and economic growth has not been properly materialized. The research findings are beneficial in prioritizing which road investments with adequate growth potentials are yielding the highest return. Correspondingly, for understanding how budget allocations could be done for the next 5-10 years so that there would be a better return on investment, and diversifying road sector investments to yield the maximum benefits for Sri Lanka. Additionally, the findings are advantageous to ensure whether there is a better balance between infrastructures and sectors that will contribute to the overall economic development of a particular area.
item: Thesis-Full-text
Implementing cycle lane facilities in eastern province in a sustainable manner
(2016-03) Theebendram, V; Bandara, JMSJ
Commuting by bicycle is a sustainable transport strategy and has advantages over other modes of transport, both for the commuter and for society. The social cohesion that can bring through recreational opportunities also promotes wellbeing. A diverse range of people choose to cycle, including school-aged children, regular commuters, weekend recreational cyclists and sporting cyclists. Cycling does not emit greenhouse gas, cause air or water pollution or rely on fossil fuels. Road Development Authority (RDA) has taken a policy decision to incorporate a separate lane as cycle lane to encourage the non-motorized transport of this country. But it is observed that these bicycle lanes are not used for its intended purpose. Especially in Colombo area, there are very few bicyclists on the roads and bicycle lanes are always empty. So, it is seen that the bicycle lanes are used to overtake vehicles in wrong side, for illegal roadside parking etc. While the situation is such. Road Development Authority is planning to extend its new policy to the areas where there are higher numbers of cycle users. Trincomalee is one of the districts in Eastern province having higher numbers of cycle users and the terrain condition also well suited for cycling. More than 50% of the road users are identified as cycle users and almost 60% of car, three wheel & motorcycle trips are less than 4 kms, a distance that is easily cycled in less than 20 minutes. These data were collected during field observation. Although cycling is an option for many commuters, a considerable number of them choose to use other forms of transport. Especially school children & office staffs, they use three wheel or motorbike as transport mode. In order to underpin policies that promote commuting by bicycle, this research investigates the determinants for commuting to work, school or their other purposes and studies about the public opinion in existing road conditions to use bicycles and their concern in cycling facilities to be provided in the future road developments. A questionnaire survey was conducted among 200 road users in different part of Trincomalee district. Accordingly, it was understood that existing road conditions such as non-availability of continue route network dedicated for Cyclists, mixed traffic without proper safety measures and parking facilities discouraged the commuters to use bicycle as their transport mode and commuters in Trincomalee district are really willing to use as a sustainable transport mode for the short trips up to 4kms, if the cycle lane facilities are provided with safety and comfort.
item: Thesis-Abstract
Evidence based fund allocation system for provincial road networks in Sri Lanka
(2022) Panagoda A; Bandara JMSJ
Sri Lanka has faced an unprecedented economic crisis during the year 2022 and the entire infrastructure development sector is now experiencing severe adverse effects. Under prevailing conditions, a cost-effective fund allocation system for all infrastructure development activities has become a mandatory requirement. Road infrastructure plays a pivotal role in sustainable development by providing required facilities for all other sectors. It can be shown that more benefits could be derived from the provincial and rural road improvement projects and road maintenance works if the funds are allocated in a scientific and logical manner. Provincial road development planning needs more research and the main objective of this research paper is to fill at least part of the widening gap between economic aspects and the technical matters related to the development of the provincial roads. Unlike trunk roads and other high-mobility roads, provincial and local roads mainly serve a predefined population group living in the command area. However, those people living in the command area do not enjoy the benefits of a proper transport system mainly due to the substandard condition that prevailed on the roads. This can be directly attributed to the ineffective fund distribution among the provincial roads. The proposed fund allocation system is based on benefits-assets criteria. Finally, it can be shown that net annual financial benefits derived from a single person living in the command area per km, is more than 500 LKR. In addition to trips generated by the people living in the command area, tourist destinations and industrial and agricultural areas are also served by the provincial roads. Part of provincial roads is used as shortcuts by minimizing the traffic congestion on the main roads. Implementing Evidence-based fund allocation for provincial roads makes a strong foundation for sustainable economic development. This research deals with the development of a cost-effective fund allocation system for the provincial road system in Sri Lanka.
item: Thesis-Abstract
Investigation of relationship between the CBR swell and other soil parameters used in road construction in identification of expansive soil
(2022) Kannangara KDIU; Pasindu HR
With the rapid growth in the construction industry in Sri Lanka, presently there is a shortage of natural resources, especially soils. Therefore, finding good quality soil that conforms to the construction specification is challenging. Expansive soils are one of the major problematic materials in the road construction industry. Clay minerals within expansive soils are subjected to significant volume changes when their environmental conditions are altered from dry to wet. Therefore, prolonged periods of drying and wetting cycles in the expansive soil can result in surface movements and distress in the road pavement which may lead to safety issues for road users and high maintenance costs to the road authorities. There are various measures used to predict the swell behaviour of soils in the road construction industry. Some of the measures which regularly used are CBR swell, shrink-swell Index, soil suction, plasticity index, weighted plasticity index, swelling pressure, linear shrinkage, clay content and cation exchange capacity. Even though some of the measures used are complex, CBR swell test is one of the simplest ways of predicting the swell behaviour of soil. As Sri Lanka is a tropical country, four days of soaked CBR is carried out as a part of the requirement of pavement design guidelines. CBR swell test is also conducted as a part of the CBR test. Therefore CBR swell data are readily available. But there is no published information on relationships between CBR swell with soil parameters for Sri Lankan conditions. Therefore, it is expected that the relevance of current specifications on quantitative estimation of soil swell using CBR swell parameter to be in this research. With that concern, the objectives of the study are to understand the nature of expansive soils and their properties, to identify the parameters of expansive soil behaviour used by engineers in road construction and then identify and quantify relationships that may exist in CBR swell with relevant soil parameters. Particle size distribution, LL, PI, PL, Soil classification, Modified compaction, CBR and CBR swell data were collected on 61 numbers soil samples and a database was prepared. Then linear regression analysis and multiple regression analysis were carried out considering PI, LL, MDD, CBR and percentage passing in the 75μm test sieve as variables in order to obtain correlations to CBR swell. Depending on the analysis, the variation of CBR swell is higher for soil types CH, CL, MH and SM and also, these soil types have shown higher CBR swell values over the other soil types. The lower CBR swell range for each soil type is less than 0.5 which is independent of whether the soil is fine-grained soil or coarse-grained soil. As per the analysis, the results from linear regression analysis, logarithmic regression analysis and multiple regression analysis, a relationship between CBR Swell and other soil parameters cannot be established. The soils which could be identified as expansive soil based on the WPI value, were not given evidence to be identified as expansive soils based on their CBR swell. The reliability of the relationships between CBR swell with soil parameters is greatly influenced by the accuracy of the CBR swell test, especially the use of correct filter paper between soil and perforated base plate of CBR mould. Hence, use of inappropriate filter paper may lead to the migration of fine particles into the soaking tank which will result in low CBR swell measurements. Therefore, it is suggested to consider CBR swell along with other swell parameters and/ or verify the results with a direct swell parameter for future studies related to expansive soil and obtaining correlations for soil swell.
item: Thesis-Abstract
Sub base improvements by stabilization techniques using waste materials
(2021) Sathiyaparathan T; Pasindu HR
Improvements of rural roads are active socio-economic passageways to a high quality of life for most of the Srilankan people living in rural areas. The fund allocated for low volume road project is limited, thus it is important to use existing resources for economic advantages. Also, adverse environmental impact can be reduced. Roads are designed for low-volume traffic and are constructed of local soils containing high percentages of fines and high indices of plasticity. These type of soils may not have certain properties pertinent for the sub base in the construction of flexible pavement in rural roads. Thus, it is necessary to modify or stabilize this kind of soil to make it suitable for construction. The soil modification process can be effectively used to meet the challenges of sustainability of the environment, to minimize the adverse effect of industrial wastes such as plastic, glass, paddy husks, etc. Wastes are multiplying day by day leading to diverse environmental concerns. On the account, the disposal of those wastes without causing any environment hazards is a real challenge. Therefore, using plastic waste, glass waste & paddy husk ash stabilizing agents is an economical utilization since there are demand and shortage of well graded soil for sub-base. This research involves a comprehensive study on the feasible use of the waste products for soil stabilization for the sub-base material in the North Central Province I-Road Project in Sri Lanka. A series of field and laboratory tests were carried out for collected sub-base materials to identify the deficiency of sub base material properties. CIDA specification for the roads was referred and confirmed to the specification for the road projects in Sri Lanka. The specification says that Liquid Limit should be less than 40 (LL<40) and Plasticity Index should be lesser than 15 (PI<15). Three different borrow pits Sub-base materials from Polonnaruwa area were stabilized with different percentage of paddy husk ash, plastic waste and glass waste with weight-based mix proportions. But the experimental study of two sub base borrow pits samples such as Mahadamana source and Sooriyaweva source demonstrated that with a 8% and 10% of optimum paddy husk ash. At the same time, the two composite samples from Mahadamana source and Sooriyaweva source were reduced the Liquid Limit by 20%, 26% and reduced the Plastic Index by 26%, 36 % accordingly. Similarly, California Bearing Ratio of the Mahadamana and Sooriyaweva composite samples were improved by 10% and 14.7% respectively. Finally, it was concluded that the stabilized composite soil can be used for the construction of flexible pavement in rural areas with low volume traffic.
item: Thesis-Abstract
Simplified approach to estimate overlay thickness for preliminary pavement design using AASHTO (1993) method
(2021) Samarasinghe SASB; Pasindu HR
In the past, Benkelman beam test is used as a nondestructive test (NDT) to investigate pavements and to do overlay designs. The main advantage of the Benkelman beam method is that using this method, an overlay design can be done without carrying out detailed investigation of the existing pavement. This is possible because, design deflections obtained from Benkelman beam test are empirically related to the overlay thickness in the Benkelman beam overlay design guideline. However, this design method has become obsolete and the field work of this test is very time consuming and labour-intensive. Thus the Benkelman beam test is not widely used at present. At present, Falling Weight Deflectometer (FWD) test is considered as the modern nondestructive testing (NDT) method for road pavements. To do a pavement overlay design with FWD data, it is required to follow AASHTO (1993) method. To do an overlay design according to AASHTO (1993) method, resilient modulus (MR) of subgrade and effective structural number of the pavement (SNeff) is required. Information of subgrade conditions is required to determine the resilient modulus of subgrade (MR). Also thickness of the pavement layers is required to determine the effective structural number of the pavement (SNeff). This means, to do an overlay design with FWD data, using AASHTO (1993) method, a detailed pavement investigation is required. During the pavement investigations, existing pavement will be damaged to some extent. Since pavement overlay designs can be done without a detailed pavement investigation using the Benkelman beam test, there is a motivation to do pavement overlay designs also using FWD test without a detailed pavement investigation. Hence, this research is conducted to formulate a simplified approach to estimate overlay thickness for preliminary overlay designs using AASHTO (1993) method using FWD data only. The developed method is called “Simplified Method” to distinguish it from AASHTO (1993) method. FWD data from four road sections are used to develop the Simplified method. In this method, MR of subgrade is determined from Surface Modulus and SNeff of existing pavement is determined from Hoffman’s method. The overlay thickness calculated from the Simplified method and the AASHTO (1993) method is compared with the overlay thicknesses given in the design reports. The outcome of the research enables the Engineer to do a preliminary pavement design during the feasibility stage of a project by using only FWD data, without carrying out a detailed pavement investigation. Thus this method will help to avoid damaging the existing pavements and save time and money for pavement investigations
item: Thesis-Abstract
Use of the digital image analysis in determination of deterioration of thermoplastic road marking
(2021) Ranawaka RADMP; Bandara, JMSJ
ABSTRACT Road safety is a major component of the highway sector and it should be well considered in highway planning, designing, construction and maintenance. The visibility of road marking is essential for efficient traffic flow and road safety. There are complaints that road markings of many roads in Sri Lanka have poor visibility and no effective remarking process in action. The major reason for the poor visibility is the low reflection levels of road markings. The visible area of road marking is the main factor for visibility. It is necessary to determine the deterioration patterns of road marking to maintain adequate remaining area of road marking on the road surface. However, there is no guideline or methodology available for road agencies in Sri Lanka to follow when deciding road marking repainting period. It is difficult to allocate funds, resource management along with stock material, manpower and machinery utilization in the most effective manner without a well-established guideline. The main objectives of this research are to obtain a comprehensive study of digital image analysis in determination of deterioration of lane marking, identify the optimum frequency of time for repainting in urban roads and introduce a guideline for repainting of road marking while integrating the guideline that can be used as a program to a road database thereby a road management tool as a future implementation. The measurements are taken in the selected section on Colombo - Horana (B084) road, Etulkotte - Mirihana - Kohuwela 120) road, Galagedera - Horana (B123) and Colombo - Galle -Hambanthota - Wellawaya (A002) road. Digital images are captured over a considerable period of time for analyzing purposes. A relationship between the time period and the remaining area of paint is developed based on digital photo-based measurements. The software of “ImageJ” is used to analyze digital photos. The relationships in between percentages of remaining areas of road marking on all types of lanes with respect to time period are found by using digital image analysis. The behavior of road marking wearing pattern is also be found relevant to the type of lane marking with respect to time period.
item: Thesis-Abstract
Analysis on suitability of built - operate - transfer systems for Sri Lankan expressways : a case study on Colombo - Katunayake expressway (CKE)
(2021) Perera MAP; De Silva D
Sri Lankan transport network achieved a significant development during the last decade by utilizing foreign concessions and local government funds for expressway development. Road Development Authority holds the authority to operate and maintain the road system periodically and mainly travel time-saving, developed infrastructure and living standards in association with social benefit are the user benefits generated with these expressways. As a developing country, a lack of financial stability for infrastructure development by 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 and Transfer (BOT) concession model is becoming a trend in the privatization of infrastructure projects. For these BOT Contracts, the concession period, interest rates are becoming the critical parameters and main considerations. In this study, a model was developed to demonstrate the potentiality of applying the BOT model for an operating expressway of Colombo-Katunayake-Expressway. The demand estimation, operational and maintenance cost, and toll revenue were used as inputs to this model and financial viability was observed with different scenarios. The concession period, interest rates, and optimality of selection of BOT were decided with different criteria based on financial viability. As the Colombo-Katunayake Expressway (CKE) meets a considerable high demand for traffic in the Sri-Lankan highway network, input variables from CKE were used to demonstrate the potentiality of applying the BOT model, and optimum subsidy level was determined with the application of variable concessionary periods to minimization of the ridership guarantee, the gap in-between the accumulated revenue and accumulated costs. Also, this BOT model is modified to validate any expressway network on an urban or suburban basis by considering the traffic demand by considering the unit length costs and unit length revenues in operations with the proposed analysis for functioning expressways in Sri Lanka. By considering main operational expressways of the country, as Southern Expressway, Outer Circular Highway (OCH), and forecasted traffic on Central Expressway and proposed Ruwanpura Expressway urban and sub-urban links were defined for the developed BOT model and operational and maintenance costs and revenue for unit length basis were obtained for iv each link. Finally, this developed BOT model was described to define and evaluate any expressway link by considering different concessionaire types obtained.
item: Thesis-Abstract
International roughness index prediction model for flexible pavements in Sri Lanka
(2021) Karunarathna E. P. N.; Pasindu H.R.
Due to the significance as an indicator of the pavement condition, International Roughness Index (IRI) is using globally as a pavement performance parameter. It also provides an idea about the riding comfort of a particular road segment and the level of riding quality. Therefore, it is using as a quality assurance criteria of roads just after construction or rehabilitation. But in Sri Lanka, there is no proper pavement performance models has been developed yet to suite our own conditions. Hence any simple planning level analysis cannot be perform due to lack of a proper performance model(s). In Road Development Authority, HDM 4 software is using for performance modelling and predictions. But, HDM 4 has developed basically taking into account of road conditions in countries all over the world. The aim of this paper is to develop an accurate IRI prediction model for Road pavements in Sri Lanka using linear regression analysis and compare it with the default HDM 4 Model. The key parameters that the IRI value directly related on a particular pavement was decided based on the literature and the availability of data. The proposed regression model from this paper predict IRI as a function of Pavement Age from construction or last Rehabilitation (years), Average Daily Traffic (ADT), Percentage of Area of All cracks identified on pavement surface (%), Percentage of Raveling Area (%) and Number of potholes. After completing three trials by changing different variables the final IRI prediction model developed is, IRI = 1.594 + 0.207 Age + 0.1202 e – ln (ADT / 10^4) + 0.1343 Ravel % + 0.0295 No. of potholes A set of available data was used to calibrate the regression model and using other set of data, relationship between the measured and predicted IRI values for the proposed model was observed using the coefficient of correlation (R- value) as a statistical measure to determine how close the data are to the fitted regression line, as the validation process. The proposed model yielded an R- value of 0.75. Finally the developed model was compared with the default HDM 4 Model which is currently using in Sri Lanka
item: Thesis-Full-text
Use of glass fibers in stone mastic asphalt for thin asphalt surfacing
(2020) Udayakantha PMAK; Mampearachchi WK
Sri Lankan road construction sector is dealing with ever depleting construction material problems, especially finding good quality aggregate has become more difficult for projects over the past few years. The accelerated development demands a lot of natural resources and the extraction of resources like aggregate on a mass scale pose a significant threat to the environment. Using the available resources sparingly and optimally is the way forward to brace the scarcity of construction material we are about to face. There are many projects in progress to upgrade low volume roads. But the designs are done using a 50mm asphalt wearing course, which is a very conservative approach given the traffic movements of the roads are very much limited. For the traffic levels in such roads, by using a thin asphalt layer which is between 25mm-35mm the same function could be achieved while cutting down construction costs for the pavement significantly. The aim is to adopt a mix that can be laid in thin layers, which performs well in Sri Lankan conditions. Therefore a Stone Mastic Asphalt(SMA) mix design was adopted, and using 60-70 bitumen and added glass fiber laboratory trials were carried out to find the optimum bitumen contents, optimum fiber contents and fiber lengths . Glass fiber was selected as the fiber due to good bitumen coating ability and availability locally. Then indirect tensile strength test was carried out for Marshalls casted in order to observe the structural properties behavior when fibers are incorporated By analyzing the results, it is concluded that a successful mix which complies with the standard can be achieved with a mix with 6.5% bitumen to weight and by adding 1.6% to 2% of glass fiber to the mix.
item: Thesis-Full-text
Evaluation rheological properties of NANO clay modified bitumen
(2020) Shantha YGPB; Mampearachchi WK; Adikary SU
Bitumen is a complex hydrocarbon, and its rheological behavior is also very complex. The rheological behavior of bitumen changes from purely viscous to elastic as per the duration of load applied and its temperature. When considering the road pavement, bitumen is the main material, and it plays a major role in many aspects of road performance. Many investigations have been done related to the modified bitumen to enhance the fulfillment of the bituminous mixture. Most of the Roads are not performed well during their whole design period and experienced rutting and cracking in the bituminous layer due to t poor performance of bituminous binders. So, bitumen modification has been the significant approach today, and modified bitumen is effectively used in many countries during the last three decades to construct pavements. This research considers a laboratory-scale assessment of the conventional and the essential rheological characteristics of modified binders using Nano clay. Montmorillonite (MMT) nano clay is widely using in many engineering applications. In Sri Lanka, few types of research were done about the usability and characterization of MMT clay, which is available at the Mannar area near the Giant tank. The clay powder prepared from the original bulk clay sample was taken from the above area. It was added to the original bitumen of 60/70 penetration grade binder to prepare the modified binder. Modified bitumen samples were prepared by adding nano clay and mixed at 1600C with a mixing time of 25minutes. The prepared modified binder with nano clay was then checked with the penetration, softening temperature, ductility, and dynamic viscosity tests to compare the properties with the original binder. Finally, modified bitumen of each sample was evaluated for the rutting and fatigue resistance for fresh and aged samples with the Dynamic Shear Rheometer (DSR) test, Rolling Thin Film Oven (RTFO) test, and Pressure Aging Vessel (PAV) test. As per the results obtained from the tests, the viscosity and softening point increase with clay percentage. Penetration and ductility have decreased with increasing clay percentage. Rutting resistance has improved compared to conventional bitumen, and it was shown that modified bitumen with 8% clay improved to PG 76 grade from PG 70 grade of the original sample. All other samples except for 8% clay showed PG 70 grade with 2%, 4%, 6%, and original bitumen sample. There was no much effect on the fatigue resistance when the samples were subjected to the DSR test after the PAV test. At the end, Fourier Transform Infrared (FTIR), Differential Scanning Calorimetry and Thermo Gravimetric Analyzer (DSC and TGA) tests have been done v for original bitumen samples as well as modified bitumen samples with 4% MMT based nano clay to verify any chemical bonds between the bitumen and nano clay. The result of FTIR and DSC/TGA has shown, no chemical interaction between the bitumen and nano clay. The conclusion from these results is that the montmorillonite clay modification supported improving the softening point from 510C of original bitumen to 530C with 4% MMT modified clay. The penetration has been reduced to 45 (0.1mm) from 60 which was in original bitumen sample with 4% MMT modified clay. The ductility value has been reduced from 151cm of original bitumen sample to 90cm with 8% of MMT modified clay. The viscosity increased from 0.38PaS of original bitumen to 0.41PaS with 2% MMT modified clay. Again, it has reduced to 0.40PaS with 4% of clay sample, and then viscosity value remains unchanged up to 8% of MMT modified clay sample. Furthermore, the rutting resistance has been increased compared to the original bitumen sample. The rutting parameter (G*/sin δ) has increased up to 2.18 with6% of MMT modified clay sample and it was 1.42 in the original bitumen sample.
item: Thesis-Full-text
Measurement of road pavement surface undulations using a low-cost accelerometer sensor
(2020) Chamikara AWC; Pasindu HR
Pavement roughness measurement is one of the four parameters of measuring the pavement condition evaluation, i.e., Pavement roughness measurement, distress condition evaluation, skid resistance, and structural capacity evaluation. This research aims to improve IRI measurement accuracy by smartphone method using a low cost, off the shelf accelerometer without compromising the cost aspect. This method collects data from an accelerometer fixed to a vehicle axel. Since the vehicle's shock absorbers do not damp the measurement, the readings are much more realistic. Data is then forwards to a machine-learning algorithm to analyze the collected data and predict the road condition. This algorithm should be trained using a training data set before using, which involves collecting and labelling data according to prior knowledge and previously collected data. The training was done by collecting data using a smartphone application and manually marking the data points. Then this data was separated as training and testing data as appropriate, and training data was fed into the algorithm with the manually labelled data as a reference. After training the algorithm, the testing dataset was provided to the model to measure the accuracy. The second part of the research was carried out to train the algorithm on detecting potholes without human involvement. For this, the data collection application was slightly modified to label the pothole data points. Then the previous training and the testing method were carried out. Accurate results were observed during both instances regarding the labelled data. It was found that more training data makes the prediction model more accurate. Since this is a low-cost method to determine the road surface condition, local road authorities can implement this as a network to collect real-time data and carry out future road maintenance works effectively.
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Effect of mat thickness for the degree of compaction of asphalt pavements
(2020) Gunasekara KKSM; Mampearachch WK
Compaction of the hot mix asphalt (HMA) is very important process in the road construction. The ability of the load bearing is greatly dependent on the degree of compaction of the hot mix asphalt pavements (Finn, & Epps, 1980). The degree of compaction depends on the various factors. The thickness of the hot mix asphalt mat is a major factor that affects to the degree of compaction. Temperature of the hot mix asphalt is very much important for the proper compaction. It is mainly governed by the layer thickness. According to previous researches, it has been shown that low thicknesses layers are rapidly drop down its temperature rather than the high thicknesses layers. This research aims at finding out, what is the optimum mat thickness of the asphalt pavements, which is suitable for the Sri Lankan conditions. In the compaction process of the hot mix asphalt layers, maximum aggregate size affects the layer thickness. 2.5 times of the maximum aggregate size has been considered as the optimal thickness for the asphalt layer. According to the guidelines of the Road Development Authorities (Sri Lanka), most of the asphalt pavements are constructed with a 50mm or lesser (40-50mm) thick layers. For this study, four road projects were selected to find out the optimum mat thickness. Thicknesses of the asphalt cores and their degree of compactions were obtained from the above projects. The cores collected in a certain range of breakdown temperatures were selected to maintain the uniformity of the samples. Maximum day time temperature and average monthly velocity details were obtained from the Department of Meteorology. The graph of core thicknesses versus degree of compaction is plotted and optimum compaction range was estimated using the graph. As per the study, it shows that, mat thicknesses within the range 55-60mm provide highest degree of compaction. It is recommended to have about 55-60mm thick mat thickness instead of having 50mm or lesser mat thicknesses to obtain highest degree of compaction of HMA layers for the selected environmental and laydown conditions.
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Evaluation of traffic forecasting accuracy in road projects in Sri Lanka
(2020) Rajakaruna D; Pasindu HR
Traffic forecasting is a significant process carried out in early stage of many transport development projects. To implement such project, it is inevitable to have benefits whilst been a feasible option. As this traffic forecast directly dealt with benefit calculations, the accuracy of forecast needs to be in high standard. There are various method and tools to forecast traffic according to past studies. Growth factors, Trend line and Time series analysis, Traffic demand Models and Simulation models are some of them. Even though models and other methods are calibrated in the design stage, very few studies carried out to evaluate the accuracy of forecast in post construction stages. In this research traffic forecast accuracy of some national highways and Three Expressways in Sri Lanka are evaluated. Southern Expressway, Outer Circular Expressway and Colombo-Katunayake Expressway are the three expressways and those are analyzed separately. Difference between forecast traffic and actual traffic is calculated w.r.t actual traffic and inaccuracy for each road sections was obtained. Forecasted traffic data was obtained by feasibility reports of highways and expressways which are gathered from Road Development Authority and University of Moratuwa. Actual traffic data was found from traffic counts done by University of Moratuwa and available data in RDA. Furthermore, factors that influence mostly on forecast accuracy are discussed. In Sri Lanka the utmost reason for Over/Under estimation is difference between estimated and actual road network considered in forecast method. Change of forecast accuracy with respect to forecast method and forecast years were plotted.
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Development of a framework for identifying highway projects for private - public - partnership financing
(2020) Tharmakulasingham K; Pasindu HR
In many cases, Public Private Partnership (PPP) projects are looked as skeptical phenomenon due to the involvement of risk factors. However, in order to reduce the financial burden on the government, it is essential to undertake PPP projects. Lack of project prioritization due to the absence of a supporting framework for selecting the infrastructure projects in Sri Lanka was identified as one of the key issues by World Bank for accelerating PPP projects. Therefore, a review was conducted to identify the criteria considered in the selection of road projects in other countries, and to develop criteria that can assist the public and private entities to identify the potential road projects in Sri Lanka. The aim of this research is to develop criteria to prioritize highway project from pipelines for the developments under PPP. As the first step, criteria which are used by USA (US Department of Transportation, Virginia Transportation, Commonwealth of Pennsylvania), Pakistan, Philippines, and World Bank for selection of PPP projects were collected. Further, Critical Successful Factors (CSF) and reasons for failure of PPP highway projects were reviewed. The importance of these factors in the selection criteria was analyzed. A Multi Attribute Analysis was used in the research. The criteria identified from other countries are subpackaged under Demand, Financial, Risk and Scale categories. A questionnaire survey was carried out with PPP and highway experts. The ranking of subpackage criteria, top six preferred criteria, and their score by nine respondents were collected. Using Garrett ranking technique, a single criterion was selected from each subpackages and used for development of preliminary screening criteria. Based on the other countries’ guidelines, the percentage responses, and scores for the top six preferred criteria, nine criteria were recommended for secondary screening. Financial viability of a project was identified as the topmost criterion to be considered in project screening. The completed and ongoing 10 expressway projects were considered, and PPP candidate nature of these projects were analyzed based on the secondary screening criteria. Preliminary screening was not carried out for the projects, because no qualifiers were developed in this study to screen out projects. Due to less information availability: financial viability, economic development, traffic congestion reduced from the projects, roles of the road in network and project cost were used for the comparison of projects. Port Access Elevated Highway was received the highest total score from the secondary screening. Major limitation in this study is that there are not any successfully completed PPP road projects in Sri Lanka, to compare our study and the real-world project scenario. In addition, another limitation was the lack of availability of detailed documentation in the projects.
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Establishment of cover depth requirement for utility pipes in arterial roads
Chathurangani, OS; Mampearachchi, WK
Pipelines are a safe and economical mean of transporting gas, water, sewage and other fluids. They are usually buried in the ground with substantial protection. Among those utilities, water convey lines would play a vital role in supplying water to the public. At present, roads have reached their maximum capacity with the increasing of the rapid growth of traffic. Thus, the rehabilitation and widening of roads shall take place to increase the structural integrity of the road pavement and road capacity. At that moment the utility agencies have to decide whether to shift the existing lines (mainly the water lines) or keep them as they are. Therefore, a criterion is needed to decide the minimum distance above the existing lines to cater the new traffic. Furthermore, the cost of removing and replacing utility lines are generally high. Considering these facts, this research intended to identify the safe depths to locate water lines in roads subjected to different traffic loadings. Existing traffic details of some arterial roads were collected from the Road Development Authority. Heights from the existing road surface to the top of underground pipelines in some of the major roads were collected. The loading calculations were done using the „CIRCLY‟ software for a selected pavement structure. Then the bending stresses were calculated using equations. Finally, the safe depth of locating pipes for satisfying the design traffic loading was determined. Furthermore, studies can be carried out on different pavement types with different thicknesses and characteristics of pavement layers
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Study the effect of vehicle composition on saturation flow at signalized intersections
Perera, PDR; Bandara, JMSJ
Signalized intersections are an essential component of a road network in urban areas where the traffic congestion has been a severe problem. Capacity is the most important factor which used for designing the signalized intersections and saturation flow rate plays an important role in determining the capacity. Therefore, saturation flow can be considered as an important parameter which is used for the planning, designing and controlling a signalized intersection. It is required to obtain the accurate saturation flow rate values to control and designing the signal timing efficiently and effectively. Many countries had executed researches regarding the saturation flow rates to suit their traffic conditions and identified the major factors which affects to the saturation flow which might be not suited for our local traffic conditions. Sri Lanka is a developing country and it is experiencing a rapid urbanization in all cities. As a result, road traffic is subjected to growing rapidly and the traffic movement has become quite complex due to all type of vehicles are sharing the same carriageway. In addition to that, those mixed traffic consist of slow moving and fast moving vehicles and vary with the size and vary with static and dynamic characteristics and maneuverability as well. With this study, it can be identified that this heterogeneous traffic condition is one of the major factor which affects the variation of the saturation flow. Large number of motorcycles and three-wheelers can be seen in the traffic stream of the signalized intersections. The objective of this study was to collect a large sample of field measurements and identify the way of pattern of varying the saturation flow with the mixed traffic condition. In that point of view, correlation was calculated with each vehicle types with the saturation flow. From the analysis, it was found that high percentage of motorcycles and three-wheelers increase the saturation flow and high percentage of heavy vehicle and cars decrease the saturation flow. Generally passenger car units (PCU) were assigned to various type of vehicles in this heterogeneous traffic condition in order to regularize the capacity calculation in a common base. However with this study it was clear that those values cannot be used as fixed values and that values also vary with the static and dynamic characteristic of those vehicles. By considering all those facts it is clear that PCU values and saturation flow rates which uses for the signal timing calculation should be reviewed and corrected to suit with the local traffic condition.