Browsing by Author "Pilanavithana, US"

Now showing 1 - 4 of 4

item: Conference-Abstract
Dynamic travel time estimation model for real time travelers
(Department of Civil Engineering, University of Moratuwa, 2011) Pilanavithana, US; Bandara, JMSJ; Pasindu, HR
A broad range of diverse technologies, known collectively as intelligent transportation systems (ITS), holds the answer to many of our society's transportation problems. ITS are comprised of existing and new technologies, including information processing, sensors, communications, control, and electronics. Combining these technologies in innovative ways and integrating them into our multimodal transportation system will save lives, time, and resources. Transportation is the backbone of our society—the movement of people and goods provides the foundation of our quality of life and economic prosperity. Various methodologies have been developed for dynamic travel time prediction. With the development of the Advanced Travelers Information Systems (ATIS), short-term travel time prediction is becoming increasingly important. As a key input for the dynamic route guidance system, travel time information enables the generation of the shortest path (or alternative paths) connecting the origins (or current locations) and destinations. Traffic estimation and prediction system (TrEPS) have the potential to improve traffic conditions and reduce travel delays by facilitating better utilization of available capacity. Moreover, a Short-term travel time prediction is incredibly significant to the real time travelers' information and route guidance system to hang on to the finest path during their route to the desired destination. In this research, to fulfill the first objective a model for estimating path flows and modifying O-D flows simultaneously is proposed based on probabilistic information (Route selection behaviour of drivers) and traffic counts. The probabilistic information is accumulated to obtain prior information on path proportions. The link traffic counts are used as sectional volume information of links. The proposed model is constructed as a two stage model. The first stage model is estimation model of path flows and the second stage model is modification model of O-D flows. Moreover, it was clarified that the proposed two stage model had enough ability to estimate path flows and to modify O-D flows accurately even when prior O-D flows had inconsistency with the current traffic conditions. By satisfying the Second objective, improved speed flow relationship employed which was focused on refining the speed estimates of network assignment models by using the modified Akçelik speed-flow model along with the literature findings. This Akçelik model produces significantly improved traffic assignment run times and provides more accurate speed estimates which lead accurate travel times to assure the last objective of identify the best path based on travel time using minimum real time information available. In Conclusion, the estimation of link flows and modifying the O - D flows can be performed by two stages modal and travel time will be projected by the improved speed flow relationship. Projected travel time facilitates the selecting best path or the alternative for the user destination. Furthermore, integrate a method which will automatically update the system data base with the latest traffic data corresponding to road links and give the most up-to-date best travel time path to the road user is proposed as future development.
item: Conference-Abstract
Economical mix design for interlocking block paving for Sri Lanka
(Department of Civil Engineering, University of Moratuwa., 2010) Pilanavithana, US; Perera, PS; Appuhami, RSBR; Mampearachchi, WK; Pasindu, HR
Rocketed trend of world wide Concrete Block Paving (CBP) adherence to the road network has already influenced the Sri Lanka as a well performing alternative for the rigid concrete pavements which caused many issues over past decades. Even though CBP in larger Production level, significant Standards and Guidelines for basic properties and manufacturing in the Sri Lankan conditions have not been introduced yet. Especially in application of CBP in trafficked road ways seems to be declined as it is not deeply concerned by the authorities due to lack of guidance. In that case the requirement of study in concrete mix design of CBP for roads phenomena was come across. In an attempt to find the a economical mix design for concrete block paving optimized combination of cementitious and aggregate materials has been developed, which contains cement, sand, quarry dust and chips in intended for the production of interlocked concrete blocks for paving in road pavement. The main purpose was to achieve optimized Concrete Blocks with fulfilling the requirements in road by using alternative aggregates, admixtures and the production cost via materials. The initial mix design was developed with the use of literature review and besides that other mix proportions were introduced by altering the initial design. First series of blocks were produced by using above mix designs by varying the aggregate-cement ratio (A/C) and water-cement ratio (W/C) between 0.25 – 0.40. Optimized value was selected considering the Compressive strength, Surface texture and Shape (edges). Next series was casted from the selected mix design and sand was replaced by quarry dust in proportion to the total fine aggregate weight. Final mix design was developed with those results and it showed significant high energy requirement compared to the first series. Seven days Compressive strength of CBP with out quarry dust was varied between 52 N/mm2 – 34 N/mm2 with in the W/C of 0.25-0.40. It was given 41 N/mm2 – 46 N/mm2 variations for the W/C of 0.30 after replacing the quarry dust with sand. This has satisfied the required strength of 35 N/mm2 for the commercial vehicles. All mix designs produced zero slumps. Compressive Strength has correlations with the A/C, W/C, Density and Sand Percentage. W/C inversely affects the shape and texture. In conclusion, Sand can be replaced by quarry dust as a successful alternative aggregate with a unique proportion. W/C ratio plays major role while restricting to upper limit to fulfill surface texture and shape. Quarry dust improves strength with a unique proportion of sand while acquiring more energy in production.
item: Thesis-Abstract
Estimate and modify O-D flows and evaluate travel time using minimal number of link flow counts
(2015-04-08) Pilanavithana, US; Bandara, JMSJ
Accurate real-time information provision and short-term predictions of traffic parameters such as volumes, travel speeds and occupancies, is a research topic that has attracted considerable interest in the literature. This is, at least in part, a result of the increasing penetration of Intelligent Transportation Systems (ITS) technologies in everyday life. ITS technologies, with Advanced Traveller Information Systems (ATIS) and Advanced Traffic Management Systems (ATMS) as examples, attempt to deal with the traffic congestion and travel time problems facing commuters in many urban areas worldwide by better synchronizing traffic signals and by assisting drivers on selecting routes based on accurate real-time information on traffic conditions. Objective of this research is to estimate and modify the Origin-Destination flows with latest traffic volume data obtained from minimal number of link flow counts within the network. Methodology in satisfying the research objective has been developed by a Dynamic Program (Dynamic Travel Time Discoverer – DTTD) in an analytical software platform widely used around the world. Developed methodology allows estimating the link flows and calculating the travel time while giving an opportunity to simultaneously modify the Origin Destination (O-D) flows according to the latest field information. During the program runs, Seed O-D Flow and Distance matrices are read by the program and calculate the total link volumes according to the seed matrices and stores in arrays. Secondly, Akçelik Speed-Flow model is used to convert total flow values into Travel Time values. A case study was carried out to validate this model to Sri Lankan conditions. This model produces significantly improved traffic assignment run times and provides more accurate speed estimates and reasonably accurate travel times to assure the objective of identify the best path based on travel time using minimum traffic flow information available. As an another option, program enables user to modify the link flow values with latest traffic data obtained from link flow counts and re-write the seed O-D Flow matrix with the updated values. When the program re-runs, it concludes the shortest path in travel time basis with the latest updates. In conclusion, the estimation of link flows and modifying the O - D flows can be performed by two stages model and travel time is projected by the improved speed flow relationship. Projected travel time facilitates selecting the best path or the next alternative for the user destination. Furthermore, integrate a method which will automatically update the system data base with the latest traffic data corresponding to road links and give the most up-to-date best travel time path to the road user is proposed as a future development
item: Conference-Extended-Abstract
Optimized Mix Design for Interlocking Concrete Blocks Using Quarry Dust for Roads in Sri Lanka
(2010) Pilanavithana, US; Perera, PS; Appuhami, RSBR; Mampearachchi, WK;
In an attempt to find a mix design where quarry dust incorporated, optimized combination of cementitious and aggregate materials has been developed which contains cement, sand, quarry dust and chips in intended for the production of interlocked concrete blocks paving in road pavement. The main purpose was to achieve optimized Concrete Blocks with fulfilling the requirements in road by using different aggregates, admixtures along with the economical production cost via materials. The analysis has indicated that the use of quarry dust instead of sand is more effective, since it is possible to include a higher percentage of quarry dust in the dosage (80% of the weight of fine aggregate) maintaining the required compressive strength in 28 days, higher than 50 N/mm2 (50 Mpa) for W/C of .30 while maintaining the shape and the surface texture. Therefore, non-conventional pre-cost block with the possibility of being extensively of being extensively used in urban and rural road networks represents contribution on standardization and economical aspects.