Transport Research Forum

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item: Conference-Abstract
Analysis of defects liability period for different type of defects identified in road construction projects
(Department of Civil Engineering, University of Moratuwa, 2018-08) Chathuranga, WAH; Pasindu, HR; Pasindu, HR
In any type of construction work there is a possibility for defects. Defects in road construction can be of many categories: road surface defects, base or sub base defects, drainage issues, design failures or construction failures. Failures can be identified using many methods. Visual observation, accident analysis, public complaints, re-testing etc are among the most common ways of identifying these defects. To minimize these construction defects, in the construction field, contractors have to use high quality materials, better construction techniques and proper machinery. Competitiveness in the construction field leads contractors to try and win the bids by bidding at a low cost. After the lowest bidder is awarded the contract, he tries to generate profits within their budget. Because of this, the contractor might tend to use low quality materials, poor construction techniques and improper machinery to make profit. To mitigate such situations and defend the client against poor construction works, the construction industry has the Defects Liability Period. Defects liability period is a set period of time after a construction project has been completed, during which a contractor has the right to return to the site to remedy defects. A typical defects liability period lasts for 12 months. However different types of defects appear after different time periods from the completion of the road construction. In common practice, Sri Lanka has one year defects liability period for all the defects in road construction projects. However, some defects may occur after one year, so contractors tend to use of low quality materials and poor supervision in road construction. Therefore employers should give carefully consider the wording and requirements of the defects rectification provisions. Where the client considers hiring another contractor to fix the original contractor's mistakes it will lead to the cost a considerable amount for the rectification of these defects. Therefore the analysing of the defects liability period for different type of defects is very much needed in road construction projects. In the recent past many roads have been re-constructed all over the country. These works were carried out by different types of contractors using different types of method statements and methodologies. Most of these contracts have had one year defects liability period. It creates many problems to relevant authorities, even though road surfaces were black top. Also few road construction projects entertain performance based contracts; such a type of contract contractor should maintain the rehabilitated road section for an agreed time period. These types of project rates of bidding items are too high compared to the normal contracts. This cost, sometimes cannot be bared. This may lead to the completion of the project far before their schedule scope due to the unavailability of funds. But most of the developing countries, including our neighbour India, focus on increasing this Defects Liability Period according to the type of defects. This study is an attempt to analyse the defects identification period in road construction, and thereby enabling the proposal of a systematic defects liability period for road construction projects. Absence of a proper defects liability period for road construction causes inconvenience to both contractors and clients. Therefore identification of the DLP would minimize imbalances and inefficiency in the construction industry. The first step is to identify the variants of defects identification. The second step is to analyse different defects with the time of identification. Road construction projects are a major variant and ten different defects components have been identified: such as road surface, base failures, sub base failures, subgrade failures, low quality materials, drainage issues, design failures, construction failures, road marking and signalling issues. To identify those defects a questionnaire survey was conducted within the Executive Engineers’ division in Kalutara District of Road Development Authority. This sample space includes three EE divisions, Kalutara, Agalawatta and Horana. Within these three EE divisions, a 450 km of national highways were maintained. In the last decade 90 percent of the road lengths were upgraded to black tops, in these divisions. Based on the results of the questionnaire, survey charts were developed for these defects, against their occurrence. This will help to identify the DLP for different type of defects in the road construction.
item: Conference-Abstract
Analysis of road accidents in “A9” roads in the Northern Province
(Department of Civil Engineering, University of Moratuwa., 2018-08) Munas, MMM; Bandara, JMSJ; Pasindu, HR
A9 (Kandy-Jaffna Highway) is the most popular road in Sri Lanka, and was opened for traffic after the renovation of the section from Vavuniya to Jaffna, in 2013. Even though several safety precautions have been provided, most number of accidents reported along the highway have occurred in the district of Jaffna, Kilinochchi and Vavuniya. Therefore, identifying locations that may lead to accidents, the cause for the accidents, and where majority of the accidents take place are essential, for immediate safety measures and improvements. The main research objectives are to identify accident prone locations, identify possible reasons for the accidents and calculate the accident rate based on vehicle travel kilometre. According to this research, fifteen most critical accident-prone locations were identified in the A9 road section from Vavuniya to Jaffna. Accident locations were grouped into the nearest 100m distance, and the fifteen most critical locations are 171+100km, 176+100km, 177+100km, 180+200km, 183+200km, 212+800km, 252+100km, 299+100km, 300+100km, 302+100km, 303+100km, 305+100km, 309+100km, 311+100km and 312+200km. Main causes of the accidents, as per the accident records, are the driving speed and the poor road environment(light condition). Driver fatigue also acted as a key factor for some accidents. Accidents that happened during day time were twice as higher than that of the night time in some locations while some were equal. However, this trend was the same in each section along the road. The highest accident rate that was around 1.31 x 10-6 veh km, was noted from Palai to Meesalai east section. Accident rates in each section have increased from year 2012 to 2014. When comparing A9 road section from Vavuniya to Jaffna with A9 road section from Kandy to Vavuniya with the same corridor geometry in 2014, A9 road section from Vavuniya to Jaffna shows a higher accident rate (0.68 x 10-6 per vehicle kilometre travelled) than other corridors (0.47 x 10-6 per vehicle kilometre travelled). In addition, fatality rate in A9 road section from Vavuniya to Jaffna has increased from 2012 to 2014, which is considerably a higher value than the fatality rates of road accidents in most of the other countries.
item: Conference-Abstract
Applicability & design requirements of an intelligent pedestrian crossing
(Department of Civil Engineering, University of Moratuwa, 2018-08) Godawita, H; Jayasooriya, N; Bandara, S; Pasindu, HR
Pedestrian crossing is one of the places where pedestrians and vehicles interact each other. This interaction often causes delays to both pedestrians and vehicles and increase possibility of accidents between vehicle-pedestrian and vehicle-vehicle. In order to manage these interactions, controlling mechanisms such as traffic signals are used. This research looks into the possibilities of making these interactions safe and less delay causing to both pedestrians and vehicles, by means of appropriate controlling mechanisms with the help of present technical capabilities. The objective of this research is to come up with a design guideline for an intelligent pedestrian crossing and to compare its effect on minimizing delays and reducing risk of accidents as compared to standard zebra or signalized pedestrian crossing. Only the isolated pedestrian crossings are considered for this study. End purpose of the research is to identify the applicability of intelligent pedestrian crossings and to identify design requirements for an intelligent pedestrian crossing at places where it is needed. Design requirements are characterized based on four main parameters; vehicle flow, vehicle speed, pedestrian flow and safe stopping distance for vehicles. The proposed design requirements allow intelligent pedestrian crossing to decide to whom to give the priority based on traffic & pedestrian flow condition and the location of pedestrian crossing. Main findings of the research include identification of different design requirements; signal operation strategies for different traffic conditions and analytical solutions to identify appropriate timing requirement of the traffic signal. Four different situations based on pedestrian flow and vehicle flow have been analysed. Intelligent pedestrian crossing will be suitable for all except the situation where both pedestrian and vehicle flows are high. It is proposed to vary amber time considering whether a vehicle can be safely stopped or whether it is allowed to pass through the pedestrian crossing. The decision is based on the approaching speed of the vehicle and its safe stopping distance. Red time and Green time could vary depending on the crossing ability (speed) of pedestrian and the crossing length.
item: Conference-Abstract
Application of level of service facilities for sidewalk assessment
(Department of Civil Engineering, University of Moratuwa., 2018-09) Hewawasam, C; Saparamadu, S; Pasindu, HR
The model share of pedestrians, in developing cities has the tendency of being very high, as opposed to developed cities. For example, between 25-50% of trips in major Indian cities, and about 50% of all trips in major African cities, are made entirely on foot. However, though such is the case, in majority of developing cities, pedestrian infrastructure, amenities, and services are often neglected in municipal planning and budgets (Fang, 2005). Improved walking facilities not only will generate new pedestrian flows, but will also increase the comfort of the current walking population. Consequently, it will result in an increase in the public transit usage and a decrease in private vehicle trips. Accordingly, a need has arisen to measure the performance of pedestrian facilities for improvements and priority setting. Traditionally, pedestrian facility operations were evaluated on the basis of the level of-service (LOS) concept. Therefore, the LOS methods used in the assessment of pedestrian facilities are to be examined in detail, to identify what is to be added or improved in the South Asian context. In response, this paper aims to study the current status of the sidewalks in Sri Lankan urban areas for the estimation of the sidewalk level of service. It reveals that the current level of services methodologies are lacking, as they address western conditions rather than the prevailing conditions in Sri Lanka. So, this study intended a review of existing methodologies by evaluating the existing sidewalks, and a combination of most appropriate factors for Sri Lankan conditions were selected. As for the review of existing methodologies, recent methodologies that developed at an international level have been selected. They are included in Table1. This study is at the initial stage and is to be developed as an “all-inclusive pedestrian facilities Level of Services methodology for South Asian Countries”.
item: Conference-Abstract
Bitumen emulsions as a stabilizer for substandard soil
(Department of Civil Engineering, University of Moratuwa., 2018-08) Udayakantha, PMAK; Mampearachchi, WK; Pasindu, HR
Sri Lankan road construction sector is dealing with an ever depleting construction material problem, specially finding good quality soil is becoming more and more difficult for projects over the past few years. The accelerated development demands a lot of natural resources and the extraction of resources like soil in mass scale also poses a great threat to the environment. Improving the substandard materials which are otherwise disregarded, can be a viable solution for the material shortage and may help environment conservation. Stabilizing the soil is a well-known practice used to improve the engineering properties of the soil. There are many ways from which the stabilization can be achieved. But a reluctance to implement it has been developed because of the time consumption, expenses, the need for expert knowledge and the need of special machinery has developed. The research is to find the possibility of using bitumen emulsions, a product which can be handled and applied rather easily as a stabilizing agent for soil. The bonding characteristics of bitumen are expected to facilitate the extra cohesion between particles, inhibit permeability and result in improved engineering properties. The idea is to find out the viability of bitumen emulsion as a soil stabilizer for Sri Lankan road projects and whether materials marked as unusable can be used for road shoulders, sub base or embankment construction after improving. To determine the characteristics of bitumen emulsion as a soil stabilizer, trial mixes, mixing bitumen contents varying from 2% to 6%, have being carried out, and the outcomes were observed. First the compaction was done soon after the mixing was finished and CBR was determined after 4 days of soaking. Since the results were not promising, the samples of the next approach were kept for five hours under normal conditions, and then compaction was done and 4 day soaked CBR was determined. The strength improvement characteristics may vary with the soil type and the construction steps followed .The curing time and the curing stage (after compaction or before compaction) has a significant effect on the strength gain. Also analysing the soil matrix at a micro level also should be done in order to get an idea about the strengthening mechanism. Emulsion is not new to road construction. It is being used extensively for other purposes such as priming and cold mixes and is a very familiar substance for the industry. Using it on the site has many advantages over other stabilizers. Therefore, finding the possibility of the applicability of bitumen emulsion as a soil stabilizer is important.
item: Conference-Abstract
Competitive assessment of container port development in Sri Lanka
(Department of Civil Engineering, University of Moratuwa, 2018-08) Kavirathna, CA; Hanaoka, S; Kawasaki, T; Pasindu, HR
Owing to the strategic location of Sri Lanka with the world maritime networks, Colombo port is developed as a main transshipment hub port, given that majority of containers throughput being represented by transshipment cargo. Within this context, the expansion of Colombo port and the development of Hambantota port were initiated by Sri Lankan Port Authority. This paper discusses the container port developments related to Colombo and Hambantota ports considering both domestic and transshipment container handling. Total domestic laden container throughput is disaggregated into 25 districts in Sri Lanka for domestic cargo flow analysis. For the transshipment cargo flow analysis, twelve selected feeder ports in the Indian sub-continent are considered, which are grouped into three feeder markets namely, Indian East-coast, South-coast and West-coast feeder markets. A discrete choice model together with the generalized cost approach, is used for modelling the gateway port choice behaviours of local shippers/consignees considering basic container haulage cost, detention fee, transport time cost, waiting time cost, and terminal handling charges. Transshipment hub port choice of shipping lines is quantified considering the range of hub port selection criteria discussed under monetary, time, port traffic, location, operation and liner related categories, according to the context of current study. The autoregressive integrated moving average model is used to forecast container volumes in 2040, which is considered as the target year. The liner programming simplex optimization method is used to calculate the additional generalized cost of shippers/consignees with the given slot capacity constraints at Colombo. Sensitivity analysis is carried out to analyse impacts from the split of liner services. High attractiveness of Colombo port for domestic container handling and Hambantota for transshipment container handling, was revealed. Scenario analysis indicates the significance of accessing the road development and incentive scheme at Hambantota port to reduce generalized cost of local shippers/consignees. The impacts from additional waiting time for liner services and slot capacity constraints at Colombo port are analysed, where a significant negative impact on local shippers/consignees was revealed. Recommendations are made considering the impacts on local shippers/consignees, shipping lines, the port authority and maritime competitiveness of the country.
item: Conference-Abstract
Criteria based funds allocation system for Sabaragamuwa Provincial Road Network
(Department of Civil Engineering, University of Moratuwa., 2018-09) Panagoda, A; Bandara, JMSJ; Pasindu, HR
Sabaragamuwa Provincial Road Network (PRN) consists of 2625 km length of class C and D roads. Majority of the roads are interconnected through Road Development Authority (RDA) road network. Sabaragamuwa Provincial Council (SPC) usually expends 750 million Sri Lankan rupees (SLR) for routine maintenance work and another 2250 million SLR in the form of capital investments. Provincial ministry of roads usually select roads for maintenance and improvement works are done on a random basis and as requested by politicians or the community. On the other hand, well-constructed PRN is very important for the sustainable economic development of the country. PRN provides transport infrastructure facilities for agricultural products and agriculture based industries. Several Provincial roads provide access to tourist attractive places like as Adams peak, water falls etc. Population of the Sabaragamuwa province is approximately 2 million and nearly 800,000 people use PRN roads for transportation purposes. Some of the PR can be effectively used to reduce the traffic congestion in the main arterial roads. As far as highways are concerned, at least there should be two lanes to accommodate the two way traffic. According to the National Highway Act, all C class roads are considered as highways. Recent survey carried out by SPRDA reveals that twenty five percent of the C class road segments have a traffic flow greater than 1000 PCU per day. However, all C class roads are still single lane roads with a carriage way width of 3.0 m to 5.0 m. SPC has already invested nearly 50,000 million SLR for road works under the capital investment projects IRDP, JICA World bank and ADB etc. Present value of recurrent expenditure is also in the range of 20,000-25,000 million SLR. This gives a clear indication that after investment of 75,000 million SLR for the improvement and maintenance of provincial roads, desired targets could not be achieved. Technical feasibility reports were prepared for individual capital investment projects and there was not any master plan to improve the entire road network cost effectively. According to the general definition, C class roads serve as collectors and connector roads and D class roads serve as collector roads and distributors. This research paper deals with the fund allocation for the PRN under different conditions. Annual allocation starting from 100 million to 20000 million SLR will be considered for the analysis. C class roads will be classified in to six groups depending on the vehicle flow rate, beneficiaries served by the road segment, interconnectivity, and present condition of the road. Similarly D class roads will be classified in to five groups. Cost benefit curves will be prepared for each group by considering capital investment as an independent variable. Dynamic programing method will be used to work out the optimum fund allocation at various stages.
item: Conference-Abstract
Design of precast concrete cover slab for pedestrian walkways
(Department of Civil Engineering, University of Moratuwa, 2018-08) Athapaththu, CJ; Perera, IMH; Mampearachchi, WK; Pasindu, HR
Pedestrians need to experience safety, comfort, accessibility, and efficient mobility. Walkways are often needed in rural and suburban areas to provide access to schools, parks, community centers, local businesses, employment centers, transit stops and stations, and Residential areas. In some areas, when no sidewalks, walkways, or shared use paths are available, pedestrians might be seen walking on roadside shoulders. Sidewalks and walkways separated from the roadway contribute greatly to pedestrian safety. Therefore whenever possible, it is necessary to furnish a sidewalk or walkway for the safety and convenience of the pedestrians. According to the Federal Highway Association, sidewalks require a minimum width of 5.0feet if set back from the curb, or 6.0feet if at the curb face to meet the minimum requirements for people with disabilities. For any two people to walk together, 5.0 feet of space is the bare minimum. According to RDA regulations minimum width of sidewalk is 1.5m. In most of the urban areas in Sri Lanka, drain area also has used as a part of the sidewalk. Sidewalks have been constructed with tactile and interlocking blocks along with precast concrete cover slabs as to cover the drain and for the mobility of pedestrians. This is mainly due to the lack of land in Sri Lankan Roadways. The existing precast concrete cover slab is designed with a hollow at the edge of the slab as to make a lengthy void when two slab panels are interconnected together. Surface water is drained out through this void strip. However the problem is these holes may be a disturbance for the pedestrians because some valuable things may fall through the voids. After having some reviews from Municipal councils and RDA, it was confirmed that more than 10 inquiries were reported weekly. Therefore people tend to cover these holes using gunny bags or some other material to avoid these disturbances. And there is a possibility of entering surrounding solid waste which would cause to block the drainage. Then the rain water will get collected on the roads and the sidewalks, and will lead to a flood. In this research, our aim is to modify the existing cover slab so as to give a safe and convenient mobility to the pedestrians. The research presented in this thesis is aimed at a novel design of a cover slab, which is being developed as a composite section of reinforced concrete and a porous concrete layer. Then the problem of draining out rain water and the inconvenient mobility of pedestrians will be solved. A cover slab model was designed using SAP2000 and the stress development was checked. Then samples were casted and tested for strength and permeability at the laboratory. Porous concrete exhibits reduction in permeability due to clogging by particulates, which severely limits service life. This research also includes the clogging mechanism and mitigating strategies of porous concrete. Samples of new cover slabs with different sized aggregates were casted using different types of compaction methods. Clogging potential of the cover slab was determined by the infiltration test (ASTM C1701). Infiltration was tested on a series cover slab samples which were clogged with topsoil, collected from the field, landscape fine compost and silt clay slurry, to simulate worse case clogging in the field. Comparison of surface texture was done according to the results of the sand patch test and clay patch test. Construction methods and practical issues related to application and mitigation techniques are discussed in this thesis.
item: Conference-Abstract
Develop material systems for next-generation infrastructure
(Department of Civil Engineering, University of Moratuwa, 2018-08) De Silva, A; Senadeera, S; Pasindu, HR
The demand for construction materials continues to rise as the infrastructure development spreads. There is a looming crisis for raw materials used in construction running low due to this high demand, and the material-intensive nature of the current construction practices adds to this. The use of novel materials and their potential applications are no longer limited to highly technical areas. The computer power developing exponentially adds another dimension to material engineering which makes it possible to develop and characterize novel materials for the next generation infrastructure. Novel materials can be in the form of novel fibers, memory materials, and bio-inspired materials. Research has been carried out to investigate the suitability of natural fibers, such as cotton, in composite construction, and how the strength properties of structural elements can be improved using carbon fibers. The potential and limitations of shape conscious materials (shape memory materials) have been studied recently. The application of such materials to enhance structural performance, and mitigate natural disasters is being investigated, and the construction industry will benefit significantly upon it being proved acceptable. Bio-inspired materials are synthetic materials whose structure, properties or function mimic those of natural systems. For example, physical properties of a material such as adhesion can embody attributes of a gecko, and self-cleaning surfaces may be inspired by the super-hydrophobic nature of a lotus leaf. They make use of the logical argument: if it works in nature, it could be scaled up to develop infrastructure. These novel materials often have improved performance aspects, and they make sustainable structural concepts feasible. For example, a novel adhesive material could offer a possibility for instruments to be attached and detached easily and self-cleaning surfaces will reduce the maintenance cost of infrastructure and also the use of chemical cleaning materials. However, developing and characterizing a novel material is a time-consuming task which represents a large commitment of resources. The operational implications such as maintainability and resilience of infrastructure built with such novel materials are to be fully understood and accepted before their implementation.
item: Conference-Abstract
Development of a choice model for school trips
(Department of Civil Engineering, University of Moratuwa, 2018-08) Sannasooriya, I; De Silva, D; Pasindu, HR
The school bus service has become more of a necessity due to two major reasons: it engages with the most sensitive crowd in the society, and operates at the most crucial time of the day. A high quality bus service is one of the most important parts of the transportation system as it will reduce the congestion by a large number. Currently it can be clearly seen that many school bus services are not up to the required standard in Sri Lanka with the lack of safety and efficient conditions. Moreover, the dissatisfaction of both parents and their children with the service, has made people switch to the alternative of using the private vehicle to commute to school. Therefore, the transportation industry is in dire need of a high quality school bus service. This study focuses on the attributes of a high quality bus service, compared to the existing transport modes for school trips. Analysis on desired attributes in a high quality school bus service and the model shift from the existing system to the new system, will be stressed. Stated Preference (SP) theory will be the main methodology utilized in the study to find out all the required data. Stated Preference survey or self-stated preference is an efficient method to analyse consumer’s evaluation of multi attributed services, specifically when there are hypothetical choice alternatives and new attributes. In the case of Colombo, Sri Lanka there are no revealed Preferences (RP) data for the high quality school bus service as it is only a Megapolis proposal. Therefore, a Stated Preference survey must be well designed and implemented. There are few objectives defined for this study such as the quantification of sensitivity to the level of service, by varying values of access time, waiting time, travel time and cost etc. to measure the willingness to pay, and to investigate effects of attitudes and perceptions. There are few most probable choice sets to commute to school around Colombo, such as using the private car, school vans and Sisuseriya or other public bus services which have numerous attributes to be considered. Furthermore, the new high quality bus service includes door to door arrivals and drop offs, information services such as Internet, telephone, and GPS navigation, a tracking system and air condition etc. The process of developing the SP survey is categorised in few major steps; I. Defining important attributes II. Designing the questionnaire of SP survey III. Experimental Design IV. Testing the Synthetic Data V. Pilot study and Analysis VI. Revising SP Survey VII. Implementing an Internet survey and supplemental presentable survey When defining important attributes, a focus group discussion will be conducted to collect data. And the questionnaire of the SP Survey will include social-economic information, current travel behaviour, attitudes and perceptions. Model Estimation will be conducted for the travel data. Different model specifications will be compared in this regard. In general, discrete choice models based on a maximum likelihood estimation technique will be used. Further, logit models will be used throughout the analysis. These models capture the influence of attributes and characteristics on the decision makers’ preferences.
item: Conference-Abstract
Development of a personal vehicle type choice model for Sri Lanka
(Department of Civil Engineering, University of Moratuwa, 2018-09) Perera, KR; De Silva, D; Pasindu, HR
Vehicle ownership is a key determination factor in any country’s economy. In the Sri Lankan context, it has been identified that vehicle ownership rate has expressively increased over the last decade. Apparently, the road congestion in urban and suburban areas also have increased significantly. As controlling measures of reducing new vehicle imports, and promoting environmental friendly vehicles, the government has introduced new taxes as well as some increments in the tax level on private passenger vehicles. The overarching object of the research was to examine how a new vehicle choice may vary in the context of household socio – economic characteristics ( eg. income level, number of households, age of the user, gender of the user etc), and the regime of new pricing reforms for annual and variable charging on the vehicle price itself (eg. fuel, insurance and other operational aspects and change of user requirements such as enhancing the vehicle seating capacity, shifting vehicle operating method etc). The respondents participating in the survey, ‘household choice of a new personal vehicle, must have purchased a new vehicle, as the survey is designed accordingly. This paper examines the development of a type of vehicle ownership model using a sample of people living in the Western Province of Sri Lanka. A sample survey is being conducted in the Western Region to collect household data in 2013. ALOGIT software is used to obtain the results of this research. This research considers several potential determinants of vehicle choice, including socio-demographic status. This study primarily attempts to identify how to recognize the family's monthly income, age, occupation, social status, and number of drivers in the family, and their influence on the ownership of the car. The main objective of this research is to help planners and traffic designers to solve the planning and traffic problems in the Western Region. In addition, the result of this research is to assist the Sri Lankan government in imposing the required taxes, and providing as much funding as possible to maximize a sustainable and environmentally friendly transportation system in Sri Lanka.
item: Conference-Abstract
Development of service quality index for sustainable bus transport
(Department of Civil Engineering, University of Moratuwa., 2018-09) Sharic, AHS; Bandra, JMSJ; Pasindu, HR
Sustainable transport is essential for achieving most, if not all, of the proposed Sustainable Development Goals (SDGs). Improvement of public transport service quality is one of the best alternatives to achieve sustainable transport goals in any part of the world. Transportation agencies can better integrate the concepts of sustainability into their planning, programming, and project development activities through performance measures. The purpose of this paper is to propose a service quality index for sustainable bus transport (SQISBT) which would enable to see how a country or region is progressing towards sustainability in transport. Reliability, convenience, comfort, safety, security and environmental standards have been identified as the main domains of service quality, in public transport. The relevant performance indicators found were waiting time, travel time, walking time, in-bus environment and station environment. Waiting time was used to reflect the domain of punctuality and reliability. Both waiting time and walking time were the indicators to reflect convenience. Comfort, safety, security and environmental standards were reflected by both in-bus environment and station environment. Waiting time refers to the time spent at a bus stop/terminal to get on a bus. Average excess waiting time (AEWT) is proposed as an indicator. AEWT is estimated as the difference between the average of actual waiting time, and scheduled waiting time. Schedules of all the bus routes in operation are to be collected, and a weighted average of a scheduled headway for bus trips are to be calculated. The schedule adherence can be monitored either using Geographical Positioning System (GPS) or bus dispatchers’ records. Average scheduled waiting time is taken as half of the average headway for frequent bus service routes which have one bus at least every twelve minutes. Decreasing score is always positive. Walking time refers to the time taken for the passengers to get access to a bus from their trip origins and the time taken to reach their trip destinations on foot, after taking the bus. This can be measured by the proportion of households within an acceptable (e.g. 500 meters) walking distance to bus stops/terminals from their trip origins. Buffer zones are to be drawn for all the bus stops/terminals and the proportion of population can be averaged for a certain district. Increasing score is always positive and the score would lie between 0 to 100 percent. The travel time means the time taken in bus travel. The average travel time per unit distance will be found out by the GPS or using published schedules, if no vehicle tracking is available for the certain locations. The weighted average travel time based on number of buses operated, is calculated, taking into consideration different routes and different times. Here, the decreasing score is always positive. In-bus environment refers to the level of comfort expected by the passengers inside bus. This can indirectly be measured by the age of the buses. Year of manufacture of buses and number of years in operation are to be collected from all the buses in an area. The weighted average value will be used as an indicator. The decreasing score is always positive. Station environment refers to the needs and expectations of the passengers at the station or halt. This can be measured by the perception on the levels of which these needs are met. Theory of Maslow’s Hierarchy of Needs was used to derive possible levels of passenger needs inside a bus while traveling. Availability of toilets, washroom, availability of seats and shelters, availability of television and entertainment, availability of categories of counters and availability of one room with all these facilities for a passenger to himself/herself are the identified indicators for measuring the perception on station environment that represent the elements of Maslow Hierarchy of Needs such as physiological, safety, love and belonging, esteem and self-actualization respectively. The score will be 1 to 5 for the respective needs. The perception should be collected from a sample of passengers representing various trip purpose, gender, level of income etc. It is proposed to normalize the above scores using weightages for these service quality parameters obtained in a previous study (Sharic,2016) and the following equation, where Z is the normalized indicator value, Xmin is the ‘worst’ value of the indicator in actual units, whereas Xmax is the ‘best’ value. Xi, c are the values to be received for the identified indicators for a certain city. Zi, c=Xi, c-(Xmin, i) Xmax, i-(Xmin, i)*100 Likewise the normalized values for the indicators will be found notated by Zwalking time, Zwaiting time, Ztravel time, Zin=bus environment and Zstation environment respectively. Then the sustainable bus transport service quality index (SBTSQI) for the certain city/village would be found by the following equation. SQISBT=5Zwalking time*Zwaiting time*Ztravel time*Zin bus environment*Zstation environment
item: Conference-Abstract
Effect of mat thickness for the degree of compaction of asphalt pavements
(Department of Civil Engineering, University of Moratuwa., 2018-08) Gunasekara, KKSM; Mampearachchi, WK; Pasindu, HR
Compaction of the hot mix asphalt (HMA) is a very important process in road construction. The ability of the load bearing greatly depends on the degree of compaction of the hot mix asphalt pavements (Finn, & Epps, 1980). The degree of compaction depends on various factors. The thickness of the hot mix asphalt mat is a major factor that affects the degree of compaction. Temperature of the hot mix asphalt is very much important for proper compaction. It is mainly governed by the layer thickness. According to the previous research, it is shown that temperature in layers with a low thickness rapidly drop down rather than in the layers with a high thickness.The research aims at finding out, the optimum mat thickness of the asphalt pavements, suitable for Sri Lankan conditions. In the process compaction of the hot mix asphalt layers, maximum aggregate affects the layer thickness. In general, it is about 2.5 times of the maximum aggregate size. According to the guidelines of the Road Development Authorities (Sri Lanka), most of the asphalt pavements are constructed with layers the thickness of 50mm or lesser (40-50mm). For the purpose of the investigation, two road projects (Jaffna-Pannai-Kayts road project and AP4-Integrated road package of Anuradhapura) were selected, to find out the optimum mat thickness. Thickness of the asphalt cores and their degree of compactions were obtained from the above projects. The cores within a certain range of breakdown temperatures, were selected to maintain the uniformity. 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 is measured using the graph. As per the investigation, it shows that, mat thicknesses within the range of 55-60mm have the highest degree of compaction. It is recommended to have a mat thickness about 55-60mm thick, instead of having 50mm or lesser mat thicknesses.
item: Conference-Abstract
The effect of water to cement (w/c) ratio on workability of internal curing concrete in the development of high strength concrete with required workability and cement content (ICBP)
(Department of Civil Engineering, University of Moratuwa, 2018-09) Bandra, MMHW; Anojan, T; Mampearachchi, WK; Pasindu, HR
The escalating demand for highways and other related structure development of any country may lead to the introduction of fast and sustainable construction techniques and materials. Internal curing is an emerging technology in the cement concrete industry, and will outperform in the road construction industry than conventional curing methods, due to it being convenient to use under harsh envirpoonmental conditions. Generally, after the placement of concrete pavements, concrete is subjected to evaporation and hydration, which causes a significant loss of moisture. That will reduce the relative humidity of concrete and increase the internal stresses. This may form micro cracks throughout the concrete, subsequently, cementitious particles may not hydrate properly. As a result of that, the durability and strength of concrete will reduce significantly. Normally, external curing methods such as immersion, ponding, fogging and wet covering are used to provide excess water, to avoid the aforementioned problems. However, those external curing methods will be effective only up to a certain thickness from the concrete surface while internal curing provides water throughout concrete using prewetted aggregates. The water will distribute uniformly throughout the concrete and reduce the humidity drop and hydrate the cement paste. The main problem in internal curing concrete is that the water added through the aggregates will affect the water cement ratio and reduce the compressive strength. This study was conducted to investigate the effect of the water cement ratio of internal curing concrete on compressive strength and workability. Concrete is cured internally by providing the required amount of water using pre wetted aggregates. These pre wetted aggregate will spread all over the concrete and help to cure the cementitious matters uniformly. Here, pre wetted burnt clay chips (internal curing concrete aggregates) are used as water reservoirs which will provide water for cement hydration. Thus, additional water added through the fine aggregates will increase the expected workability. Results are obtained by adjusting the water content and then workability, and compressive strength values are compared. Results showed that water/cement ratio reduces, and compressive strength increases with ICCA for all grades of concrete, tested in the study.
item: Conference-Abstract
Evaluation and improvement of toll collection system in Sri Lankan expressways - case study for Colombo-Katunayake Expressway
(Department of Civil Engineering, University of Moratuwa, 2018-08) Kumara, HBNS; De Silva, GLDI; Pasindu, HR
With the latest development, three expressways were opened to the public in Sri Lanka and the number of users of the expressway network is expected to rise. The pay toll system in the road is based on the traditional method, which is the collecting of the toll by road barriers installed at the entrance & exit points of expressways. Although in this system the toll is collected directly from the drivers, the existence of barriers causes increased travel time, increased fuel consumption and consequently increased pollution in the road environment. For a more continuous flow of traffic, an Electronic Toll Collection (ETC) system was introduced in Colombo – Katunayake Expressway (CKE) since June 2015 to help alleviate traffic congestions, reduce environmental pollution, reduce cash circulation, integrate the financial system, elevate passenger comfort, and specifically reduce the service time at Toll Plazas. This research focuses on the economic and technical analysis of the existing toll collection systems in the Colombo-Katunayake Expressway. The study is aim to evaluate the newly established ETC Toll collection System CKE. In detail, the objective is to assess the amount of delay of the individual lanes dedicated for MTC and ETC, their service time, lane capacities and the forming of the queue in each lane and compare with the different modes of toll systems used in other countries. The study also aims to find out the specific factors that affect the delays experienced at Toll plazas & decrease the system performance, and recommend ways to improve the service. Not only that, the study is focused on the evaluation of the economic loss caused by the delays in toll lanes and level of lane utilization by each mode of vehicles. The analysis of the current toll systems in CKE under the system, financial, traffic, environmental, infrastructure and socio-economic aspects would be conducted using SWOT method. Then, the different toll collection methods & technologies are to be studied under this research and characteristics and performances of each individual technology is to be compared. Analysis would be done to identify the appropriate ETC toll collection method for Sri Lankan Expressways. Consequently, short-term and long-term recommendations, for the Sri Lankan road tolling system, will be proposed, in terms of transportation.
item: Conference-Abstract
Evaluation of rheological properties and performance of asphalt binder modified with nano clay
(Department of Civil Engineering, University of Moratuwa., 2018) Shantha, YGPB; Mampearachchi, WK; Adikary, SU; Pasindu, HR
The rheological behaviour of bitumen is very complex and it can vary from purely viscous to elastic, depending on the loading time and the temperature. Bitumen plays a major role in many aspects of road performance. Various investigations have been carried out related to the modified bitumen, to improve the performance of bituminous mixtures. Most of the Roads have failed due to the rutting and cracking of the bituminous layer, which is mostly due to the poor performance of bituminous binders. So, the modification of the bitumen is a major approach, and modified bitumen has been effectively used in many countries to construct pavements during the last three decades. This research presents a laboratory scale evaluation of the conventional and the fundamental rheological characteristics of modified binders with micro clay and Nano clay contain 2%, 4%, 6% & 8% by its weights. Engineering fields widely use montmorillonite (MMT) Nano clay for a wide range of applications. In Sri Lanka also, there had been research about the usability and characterization of MMT clay available at Mannar area near the Giant tank. The clay powder prepared from the original samples taken from the above area were added to the original bitumen of 60/70 penetration grade binder to prepare the modified binder. Modified bitumen samples were prepared at a mixing time of 25 minutes by adding Nano clay mixed at 1600C. The properties of the modified binders with Nano clay were evaluated in terms of penetration, softening temperature, ductility and dynamic viscosity tests. Finally each sample of modified bitumen was evaluated for rutting and fatigue resistance for fresh and aged samples with the Dynamic Shear Rheometer (DSR) test. It was observed by the results obtained from the tests that the softening point and viscosity increased up to 4% clay, penetration and ductility had decreased with the increasing of clay percentage. Rutting resistance had not improved compared to conventional bitumen and it showed that modified bitumen and the original sample showed PG 70 grade with 2%, 4%, 6% and original bitumen sample. It can be concluded that the montmorillonite clay modification helped to improve some characteristics of the bitumen binders. But at this level they are not at a stage enabling the verification of their application at a large scale.
item: Conference-Abstract
Evaluation of roadway-railway level crossings in main line from Colombo to Polgahawela
(Department of Civil Engineering, University of Moratuwa., 2018-08) Ragulan, K; Amarasingha, N; Pasindu, HR
When a railway line crosses a road or a path at the same level, it is called a Level Crossing (LC). The total length of the railway lines in Sri Lanka is approximately 1930 km (SLR, 2011). 1047 crossings have been reported. Out of these, 128 crossings are protected by electrical barriers and 139 are protected by mechanized barriers. A great amount (758) is manned by barriers while an amount as low as 17 are manned by farm type gates. About 151 gates have a bell and flash light system. There are about 457 unprotected gates in the country, accounting for 37%. The main objective of this study is to evaluate the railway-roadway LC safety, because a significant number of rail crashes are being reported in Sri Lanka at LC. Four years of railway crash data, LC characteristics, rail line characteristics, and highway characteristics, were collected at the main rail line from Colombo to Polgahawela. Special attention was paid to different types of LCs, focusing on their methods and their functional capacity. Furthermore, the shortcomings found in the system were analysed using data pertaining to the 62 LCs found between Colombo to Polgahawela. The details regarding these LCs, their nature, construction, location, and intermittent distances were obtained directly from the Railway department. Then linear regression models were used to identify whether these predictor variables, which successfully predict an outcome, crashes. The locations which had appalling shortcomings such as the unavailability of barriers found in the LC, the prolonging of the bell sound for a considerable time, the elderly being employed in unprotected LCs without their basic facilities or wages being ensured, LCs and roadways running parallel and road traffic getting entangled in the LC, and the view of approaching trains getting blocked by towering buildings and trees, were successfully identified. Based on the data collected, the locations that needed immediate attention were pointed out. Statistical analysis further showed that the distance to the nearest curvature from the direction of Colombo and Polgahawela, the sight distance from the upside and the bottom, availability of a passive protection system, have a significant influence on the occurrence of crashes. The main intention of this research is to minimize the number of accidents that occur at the crossing of main line. The sample taken for the study is convenient, due to the fact that the population can be accessed appropriately. The results can be considered as general, though there might be slight variations that could arise, as some of the LCs, especially in the rural areas of the country, have less trains and vehicles on roads. Furthermore, some solutions and recommendations have been put forward, taking into consideration the modern methods utilized in this field.
item: Conference-Abstract
Improvement of aggregate packing model of interlocking concrete block pavement (ICBP) mixture using fly ash
(Department of Civil Engineering, University of Moratuwa., 2018-08) Batuwita, IP; Mampearachchi, WK; Pasindu, HR
Use of concrete paver blocks is becoming increasingly popular. They are used for paving approaches, paths and parking areas, including their application in pre-engineered buildings and pavements. Interlocking Concrete Block Pavement (ICBP) has been extensively used in a number of countries for quite some time as a specialized problem-solving technique, to provide pavements in areas where conventional types of construction are less durable due to many operational and environmental constraints. This research is conducted in order to improve aggregate packing model of ICBP by using Fly ash. In Sri Lanka, Lak Vijaya Coal Power Station at Norocholai, Puttalam generates large amount of fly ash per day as a by-product. It was considered a waste & an environmental hazard, thus its use was limited. Within this research, this waste & hazardous fly ash is used as a filler material in paving block mixture to optimize the packing of aggregate. These fly ash samples & control samples were tested for compressive strength, water absorption and Scanning Electron Microscope Analysis. Experimental results showed that 23 and 21 percent of cement can be replaced by Fly Ash in Grade 15 & 20 mixtures respectively. Fly ash has reduced the cement needed for ICBP mixtures. Optimization of packing of aggregate is the process of determining the most suitable aggregate particle size and distribution, to minimize the voids content of an aggregate mix. An optimized aggregate mix will have a lesser amount of voids which need to be filled with cement paste. Further, fly ash has improved the workability of the mixture due to the special nature of the particle. The use of fly ash in concrete paver blocks has reduced the cement content, and heat of hydration, leading to better economy and durability. It will also help safeguard the environment from the adverse effects of CO2 emissions from the cement industry, and provide a solution for the disposal issue of fly ash produced by thermal power plants.
item: Conference-Abstract
iRoads: smartphone-based road condition monitoring
(Department of Civil Engineering, University of Moratuwa., 2018-08) Abeywardana, HMA; Abeywickrama, UMJ; Amarasingha, PT; Kumarasinghe, RPD; Bandara, HMND; Pasindu, HR; Pasindu, HR
Measuring and monitoring road conditions are essential to ensure public and vehicle safety, prompt maintenance, as well as fuel and time savings. While developed countries use sophisticated devices installed on specialized vehicles to measure and monitor the road conditions, it is cost prohibitive for countries like Sri Lanka. Moreover, the diversity of road types and non-standard physical properties, make it impractical for specialized vehicles to travel on roads in Sri Lanka and many other countries. Therefore, a system that is low cost and practically usable on roads with non-standard physical properties will be a useful solution for road condition monitoring. Sensors such as 3-axis accelerometer, gyroscope, GPS, and magnetometer in most smartphones could be used to detect potholes and bumps, as well as to estimate International Roughness Index (IRI) at a much lower cost. Related work has shown that acceleration data from smartphones have a linear relationship with road roughness. Hence, it opens the way to the development of a system to measure the road roughness using smartphone sensors. While the accuracy of such a solution is relatively low, with the increasing number of motorists with smartphones, crowdsourcing could be used to collect data at a high spatial and temporal resolution that has been hitherto impossible. Such a massive volume of data collected through crowdsourcing could be processed using machine-learning and signal processing algorithms, such that the limitations and low accuracy of a single smartphone could be overcome by data analytics of the same road condition again and again. A crowd sourced mobile app is proposed, to measure the road conditions such as potholes, bumps, speed breakers, and estimate IRI at a high spatial and temporal granularity. The proposed solution collects data over a broadband connection to a cloud-computing-based backend where machine-learning and signal processing algorithms are used to determine different road conditions and estimate IRI. Moreover, the solution provides visualization of this information using a map-based dashboard. 3-axis accelerometer is used as the main source for road profile monitoring. However, in a crowd sourced model, many practical problems need to be solved in addition to technical problems, as motorists may use vastly different types of smartphones with varying features and accuracy. For example, they may mount the smartphone in various orientations or orientation may change as the trip progresses. Therefore, a reorientation mechanism is essential to convert accelerometer data from any arbitrary smartphone position to the vehicle’s axis. The solution implements two reorientation mechanisms. The first mechanism is using Euler angle-based algorithm. The second mechanism uses magnetometer and GPS bearing readings to reorient the acceleration vectors of the mobile device. Signal processing techniques are used to filter out the sensor noise for more accurate data gathering. Moreover, the magnitude of sensor reading tends to correlate with acceleration and deceleration of the vehicle. Thus, vehicle speed data are also needed to capture road conditions accurately. Therefore, the proposed app connects to an OBD2 (On-Board Diagnostic) ELM327 adapter to collect vehicular data such as fuel consumption and speed of the vehicle. OBD2-based vehicle speed estimation is more effective than GPS-based estimation due to the low resolutions and slow sampling in GPS. Random-forest algorithm is used in the backend to detect road anomalies (e.g., pothole or bump), while pulse calculating algorithm is designed for estimating IRI values. Road segments are classified based on IRI and a map is annotated based on the IRI values. Due to varying accelerometer accuracy levels, as well as low resolution and slow sampling in GPS, it is difficult to estimate the exact location of the road anomaly. Therefore, a clustering algorithm is used to identify the location of an anomaly by clustering GPS locations estimated from different trip data provided by users. Moreover, vehicular data will be used in the future to estimate the relationship between fuel consumption and IRI of Sri Lankan roads. Furthermore, the visualization of bad road segments could provide insights to drivers to bypass bad road segments while the authorities could use the dashboard to prioritize maintenance and policy marking. An Android-based mobile app, namely iRoads, is developed and already used with a few data collection trails. The research currently focuses on calibrating the mobile app and related algorithms to accurately estimate IRI and detect road anomalies. For example, efforts are currently underway to calibrate estimated IRI values with the IRI readings from a ROMDAS Bump Integrator. The goal is to improve the accuracy to such a level that iRoads could measure roughness like a class-3 road profiling instrument. Another app is also developed to label road anomalies on the go, such that a large, labelled training dataset could be gathered for training and evaluation of machine-learning and signal processing algorithms. Based on this, dataset model parameters are to be tuned to more accurately estimate road anomalies.
item: Conference-Abstract
Modified 3 parameter model incorporating particle shape, texture and vibration to predict packing density of binary particulate mixtures
(Department of Civil Engineering, University of Moratuwa, 2018-09) Hettiarachchi, HACK; Mampearachchi, WK; Pasindu, HR
Particle packing density is one of the most important parameters in materials engineering. Ultra-high-performance concrete (UHPC), lightweight concrete, porous concrete, advanced ceramic materials, porous asphalt, filter materials are some of the major applications based on the packing density. Determination of packing density of a particulate mixture is a complicated and a laborious process. Hence, many researchers investigated the behaviour of particulate systems in a confined space in order to develop mathematical relationships to predict particle packing density. Several particle packing models have been developed so far such as Toufar model (Toufar, Born, & Klose, 1976), Compressible packing model (CPM) (Sedran & De Larrard, 1999) , 3-Parameter model (Kwan, Chan, & Wong, 2013), Linear packing density model (Stovall, De Larrard, & Buil, 1986) etc. However, due to the complexity of the particulate systems, many of these models are based on several basic assumptions; spherical shape, random loose packing method, smooth particles etc. A study carried out by Hettiarachchi and Mampearachchi (2017) revealed that the packing models can be effectively utilized to improve concrete mixtures for Interlocking concrete block pavers (ICBP). Nevertheless, the study also revealed that the packing models do not accurately predict the packing densities and 3-parameter model predictions are showing a close relationship with the actual packing densities. Hence, the objective of this study was to modify the 3-parameter model incorporating particle shape, surface texture and vibration frequency. A vibration table and a vibration hammer were used to apply vibration to the particles. Spherical glass beads were quoted with sand dust of various sizes to achieve different surface textures. Aggregates of various shape factors were taken to investigate the effect of shape. Each effect was isolated, and the packing density of the mixtures were measured varying the large particle volumetric fraction. Effect of the size ratio was also investigated by varying the size of the two particle classes of the mixture. The variation of packing density with vibration, shape and texture were analysed and the combined effect was modeled using regression analysis. The 3-parameter model was then modified using back calculation techniques to develop relationships with each effect. The modified 3-parameter model was validated using over 300 experimental data. The modified 3-parameter model found to be in correlation with the experimental data with a correlation coefficient of 0.95. In conclusion, the developed model will be able to predict the packing density of complex mixtures with high accuracy to provide more realistic outcomes which will benefit the materials engineering greatly.