Browsing by Author "George, V."

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A comparative study on properties of porous friction course mixes with neat bitumen and modified binders
(2009) Suresha, S.N.; George, V.; Ravi Shankar, A.U.R.
This paper summarises details of the laboratory investigation on the effect of various binders on the performance and durability of porous friction course (PFC) mixes. Three different modified binders and neat bitumen were investigated for three different aggregate gradations at two predetermined binder contents. The performance was evaluated in terms of stone-on-stone contact condition, air voids, and hydraulic-conductivity of compacted PFC mixes. The structural durability was investigated based on aged abrasion loss and moisture susceptibility. The findings provide a better understanding of the effect of each binder type on the performance and durability of PFC mixes. Crown Copyright © 2008.
A model study on accelerated consolidation of coir reinforced laterite and blended shedi soil with vertical sand drains for pavement foundations
(2012) George, V.; Santosh, G.; Hegde, R.N.; Durga Prashanth, L.; Gotamey, D.; Ravi Sankar, A.U.
Sub-grade soils of lateritic origin are frequently encountered in the construction of highway embankments in various regions of India, often comprise intrusions of soft lithomargic soils that result in large settlements during constructions, and differential settlements at later stages. This necessitates the use of appropriate soil improvement techniques to improve the load-carrying capacity of pavements. Coir is a natural fiber that can be used in place of geosynthetics and geogrids, and it is biodegradable and environment friendly. This work deals with the accelerated consolidation of un-reinforced and coir-reinforced laterite and blended lithomargic soils, provided with three vertical sand drains. The load-settlement characteristics were studied for various preloads ranging from 50kg (0.0013 N/mm2) to 500kg (0.013N/mm2) using circular ferro-cement moulds. It was observed that at lower preloads up to 300kg, the relative increase in consolidation (Cr) for randomly reinforced soil with vertical drains was significantly higher than that of un-reinforced soil without vertical drains. Also, the Cr for un-reinforced soil with vertical drains was quite higher than that of un-reinforced soil without vertical drains, with values above 38.71%. However, in the case of higher preloads of 450kg and 500kg, the Cr for randomly reinforced soil with vertical drains was insignificant, and the Cr for un-reinforced soil with vertical drains remained slightly higher at around 9.59% for similar comparisons. The aspect-ratio of coir fibers used was 1: 275. © 2012 Cafet-Innova Technical Society. All rights reserved.
Accelerated consolidation of coir reinforced lithomargic laterite soil blends with vertical sand drains for pavements
(2012) George, V.; Hegde, R.N.; Vardhana, M.V.; Santosh, G.; Gotamey, D.
It is found that sub-grade soils of lateritic origin encountered in the construction of highway embankments in various regions of India, often comprise intrusions of soft lithomargic soils that result in large settlements during constructions, and differential settlements at later stages. This necessitates the use of appropriate soil improvement techniques to improve the load-carrying capacity of pavements. This work deals with the accelerated consolidation of un-reinforced and coir-reinforced laterite and blended lithomargic soils, provided with three vertical sand drains. The load-settlement characteristics were studied for various preloads ranging from 50kg (0.0013 N/mm2) to 500kg (0.013N/mm2). Studies were performed using circular ferro-cement moulds. It was observed that at lower preloads of up to 250kg, the relative increase in consolidation (Rct) for randomly reinforced soil with vertical drains was significantly higher than that of un-reinforced soil without vertical drains. Also, the Rct for un-reinforced soil with vertical drains was quite higher than that of un-reinforced soil without vertical drains, with an average value of 20.84%. In the case of higher preloads the Rct values for randomly reinforced soil with vertical drains were moderate with an average value of 22.67%. An additional increase of up to 27% at lower pre-loads and 11.83% at higher pre-loads was observed due to the effect of random reinforcement when compared to use of vertical drains alone. © 2012 ejge.
Assessment of Efficiency and Effectiveness of Bus Transport Organizations Using DEA Incorporating Emissions and Accidents
(Institute for Transport Studies in the European Economic Integration, 2023) Praveen Kumar, P.; George, V.; Mulangi, R.H.
Environmental pollution due to vehicular emissions and accidents reflect upon the sustainability, and social responsibility of transport organizations. However, it is also necessary to attain higher levels of performance by ensuring higher transit ridership measured in terms of passengers carried per day. The present work is focused on the analysis of performance efficiency and service effectiveness of 25 selected State Road Transport Undertakings (SRTUs) in India for the year 2004-05, 2009-10 and 2014-15. Here, it was proposed to use a hybrid output-oriented Data Envelopment Analysis (DEA) approach developed by Seiford and Zhu in 2002 to handle undesirable outputs such as annual Carbon-di-oxide (CO2) emitted per passenger-km, and total accidents per year in addition to overall productivity. The results of the analysis provided details on targets that could be achieved for the available input resources allocated. Transport organizations can adopt similar approaches in performance evaluation and benchmarking considering sustainability, and social responsibility along with efficiency. © 2023 Institute for Transport Studies in the European Economic Integration. All rights reserved.
Basics on Categorizing Travel-Time-Based Degrees of Satisfaction Using Triangular Fuzzy-Membership Functions
(Elsevier B.V., 2020) Anand, A.; George, V.; Kanthi, R.; Tagore, M.; Padmashree, M.S.
The travel desires of trip-makers in urban activity centres depend mainly on the location of residential areas, proximity to various activity centres, household characteristics, and socio-economic factors that influence the choice of travel modes. Decision-making with regard to the choice of a particular mode of travel is fuzzy in nature, and seldom follows a rigid rule-based approach. In this context, the fuzzy-logic approach was considered since it could handle inherent randomness in decision-making related to mode-choice. The present study focuses on the application of this technique making use of revealed preference survey data collected through CES and MVA Systra, later compiled and corrected in various stages at NITK. The difference between the actual travel time by a particular mode, and the theoretical travel time based on average vehicular speeds was used as an important indicator in determining the degrees of satisfaction of the trip-maker. This indicator was computed, and fitted using a normal distribution. It was assumed that indicator values between Î¼-3Ïƒ and Î¼ could be considered for the category of satisfied trip-makers according to the three sigma rule where Î¼ is the mean indicator value, and Ïƒ represents the standard deviation. The computed values of the indicators were used in classifying the data into 6 categories of degrees of satisfaction that formed the basic framework for modelling using fuzzy-logic technique. This paper aims at understanding the basic mathematical computations involved in defuzzification using the centroid method for triangular membership functions, and provides a comparison with results obtained using MATLAB. Â© 2020 The Authors. Published by Elsevier B.V.
Bus passenger demand modelling using time-series techniques-big data analytics
(Bentham Science Publishers B.V. P.O. Box 294 Bussum 1400 AG, 2019) Cyril, A.; Mulangi, R.H.; George, V.
Background: Public transport demand forecasting is the fundamental process of transport planning activity. It plays a pivotal role in the decision making, policy formulations and urban transport planning procedures. In this paper, public bus passenger demand forecasting model is developed using a novel approach. The empirical passenger demand for a bus depot is modelled and forecasted using a data-driven method. The big data generated by Electronic Ticketing Machines (ETM) used for issuing tickets and collecting fares is sourced as the data for demand modelling. This big data is time indexed and hence has the potential for use in time-series applications which were not previously explored. Objectives: This paper studies the application of time-series method for forecasting public bus passenger demand using ETM based time-series data. The time-series approach used is the four Holt-Winters’ modeling methods. Holt-Winters’ additive and multiplicative models with and without damping have been empirically compared in this study using the data from the inter-zonal buses. The data used in the study is a part of the transaction on ticket sales by Kerala State Road Transport Corporation (KSRTC) maintained at the Trivandrum City depot of an Indian state Kerala, for the period between 2010 and 2013. The forecasting performance of four time-series models is compared using Mean Absolute Percentage Error (MAPE) and the model goodness of fit is determined using information criteria. Conclusion: The forecasts indicate that multiplicative models with and without damping, which better account for seasonal variations, outperform the additive models. © 2019 Cyril et al.
Calibration of Vehicle and Driver Characteristics in VISSIM and ANN- based Sensitivity Analysis
(International Microsimulation Association, 2020) Bandi, M.M.; George, V.
Traffic- flow modeling using microsimulation approaches facilitates the study of bottlenecks and assists in the analysis of traffic- flow characteristics, the movement of individual vehicles, and in the study of vehicle and driver characteristics. The present study focuses on performing investigations on assessing the infuence of vehicle and driver characteristics on accurate prediction of traffic volumes in Mangalore city road network. The multi- stage frst- level of calibrations were performed starting with default values of vehicle and driver characteristics followed by testing of various combinations. The accuracy of predicting simulated volumes was measured using GEH- statistic. An ANN- based sensitivity analysis was performed to find the relative importance of vehicle and driver characteristics, which revealed that the average standstill distance, minimum look- ahead distance, and the desired speed: lower bounds for speed distributions were highly sensitive. The second- level of calibrations were performed by fne- tuning these three characteristics in three stages and the fnal VISSIM model was validated. © 2020, Bandi and George.
Characterization of porous friction course mixes for different Marshall compaction efforts
(2009) Suresha, S.N.; George, V.; Ravi Shankar, A.U.R.
Porous friction courses (PFCs) are mainly recommended as surface drainage layers on high-speed road-corridors and runway pavements. Permeability and sound attenuation characteristics are considered to be the indices for performance assessment of PFCs. One of the reasons for the loss of permeability in PFCs is densification under heavy traffic. But, resistance to ravelling too, is of main concern in the case of under-compacted PFCs. This paper summarises the details of laboratory investigation on the characterization of PFC mixes corresponding to four different gradations and two binder contents, for three levels of the Marshall compaction. The findings of the investigation suggest that the selection of the compaction level for PFC mix design should be based on the design traffic level, and the gradation selected. © 2009 Elsevier Ltd. All rights reserved.
Demand-Based Model for Line Planning in Public Transport
(Elsevier B.V., 2020) Cyril, A.; Mulangi, R.H.; George, V.
A public transport network serves the society effectively if it evolves in time according to the changes in the population. Urban transportation problems of Thiruvananthapuram, a typical Indian city, is mainly due to the lack of evolution of the planned network adhering to the rapid urbanization and motorization. These issues are managed by constructing more infrastructure, which act as the catalyst to major urban problems, rather than addressing the cause. The purpose of this paper is to analyze the public transport operational characteristics of a typical Indian City (Thiruvananthapuram) emphasizing on link load on the selected route. In this paper, a methodology is proposed for line planning problem which includes optimization of public transport lines using operator costs, user costs and crowding on the bus. It also includes the determination of peak and off-peak frequencies of the existing network lines considering the critical demand. Â© 2020 The Authors. Published by Elsevier B.V.
Development of a GIS-based composite public transport accessibility index
(Universidade Federal da Paraiba celso@ct.ufpb.br, 2019) Cyril, A.; Mulangi, R.H.; George, V.
The increasing interest in sustainable modes of transport such as public transport has triggered the need for evaluation of accessibility to and from the transit service. Accessibility to the transit service determines the service attractiveness and hence better accessibility increases the demand. Although accessibility has been the focus of research in the past few decades, it still remains a concept that has been poorly defined and hence finding a theoretically good and operationally sound measure of accessibility is a challenging task. The objective of this paper is to develop a composite public transport accessibility index using Geographic Information System (GIS) as a case study of an Indian city, Trivandrum. This concept is a spatio-temporal GIS-based public transport accessibility model which includes travel modes of walking and bus transit, travel impedance and service coverage of the transit network. The methodology used in the study is based on the factor that the index should measure the accessibility which comes from proximity to bus stops and land use destinations and the proportion of the population served. © 2019 Journal of Urban and Environmental Engineering (JUEE). All rights reserved.
Effect of aggregate gradations on properties of porous friction course mixes
(2010) Suresha, S.N.; George, V.; Ravi Shankar, A.U.
This paper presents the study on effect of aggregate gradation on the mix design and performance properties of porous friction course (PFC) mixes. Six aggregate gradations were tested with due consideration to gradations specified for PFC or similar mixes by different agencies around the world. The PFC mixes were characterized for volumetric properties, permeability, unaged and aged abrasion loss, moisture susceptibility, and rutting resistance. The results were statistically analysed to identify the factors that significantly influence the properties of PFC mixes. Findings of the study clearly indicate that the gradations specified by various agencies will have significant effect on the design properties of PFC mixes, thus they are different. It also, helps in framing the Master aggregate gradation band for PFC mixes. Generally, permeability property is considered to be an optional parameter in the design. However, the findings of the present study recommended considering the permeability as one of the prime parameters in the design of PFC mixes. © RILEM 2009.
Effect of soil parameters on dynamic cone penetration indices of laterite sub-grade soils from India
(2009) George, V.; Nageshwar Rao, Ch.; Shivashankar, R.
The focus of this study was on correlating the effect of grain-size, maximum dry-density (MDD), field moisture content, and the void ratios on penetration measured using the dynamic cone penetrometer (DCP) for laterite soils blended with fines. Tests were performed on soil samples compacted to MDD for moulding water contents set to the optimum moisture content (OMC), dry of OMC, and wet of OMC un-soaked condition. The results indicated that an increase in the fines-content caused a decrease in the MDD, and an increase in the OMC and the DCP penetration. Regressions were developed correlating various parameters. © Springer Science+Business Media B.V. 2008.
Effect of soil parameters on modulus of resilience based on portable falling weight deflectometer tests on lateritic sub-grade soils
(Taylor and Francis Ltd. michael.wagreich@univie.ac.at, 2020) George, V.; Kumar, A.
The use of portable falling weight deflectometers (PFWDs) has gained prominence among pavement engineers in the characterisation of soil sub-grade based on modulus of stiffness. The values of modulus of resilience and the corresponding values of the rebound deflection measured using the PFWD are largely influenced by the soil stiffness. The focus of the present investigation is on the study of the effect of soil parameters such as grain size distribution, maximum dry density (MDD) and optimum moisture content (OMC) on the values of modulus of stiffness (E PFWD) obtained using the PFWD for tests performed on lateritic soil blends. Tests were conducted on various blends of lateritic soil samples compacted to MDD at moulding water contents set to the optimum moisture content (OMC), dry-side of optimum at OMC?3% and wet-side of optimum at OMC+3%. The regressions developed between the values of E PFWD and the percentage of fines and the percentage of sand for lateritic and lithomargic soils indicate a strong linear relationship between these variables for tests on un-soaked and soaked soils. The regressions developed will be of immense benefit to pavement engineers in estimating the values of the modulus of resilience for lateritic soils for the design of pavement sub-grades and embankments. © 2017, © 2017 Informa UK Limited, trading as Taylor & Francis Group.
Effect of Soil Parameters on Resilient Modulus Using Cyclic Tri-Axial Tests on Lateritic Subgrade Soils from Dakshina Kannada, India
(Springer International Publishing, 2018) Kumar, A.; George, V.
Resilient modulus (Mr) of a soil is used as a basic input in the analysis of sub-grade and sub-base in the mechanistic empirical design approaches. The present work focuses on evolving a cost effective approach for the determination of resilient modulus in the laboratory based on tests performed using the CBR method, and the DCP. Lateritic sub-grades in India exhibit wide-ranging variations in strength and stiffness due to varying fines content, and other characteristics. Additionally, soils of lateritic origin with a higher proportion of fines, also called as lithomargic soils, pose difficulties to pavement engineers due to the poor supporting strength. In order to investigate the strength and stiffness of a wide variety of lateritic soils, it was proposed to perform tests on lateritic soils blended with lithomargic fines in this study. The study focuses on correlating the effect of grain-size, maximum dry-density (MDD), and optimum moisture content (OMC) on the resilient modulus (Mr) measured using the cyclic tri-axial test for various blends of lateritic soils. Tests were performed on soil samples compacted to MDD for molding water contents set to the OMC, dry-side of OMC, and the wet-side of OMC. The results indicated that an increase in the fines-content resulted in an increase in the OMC, and a decrease in the MDD and Mr values. Regressions were developed correlating the fines content to the resilient modulus. This study is expected to provide the necessary basis for estimating the strength of a wide variety of lateritic sub-grades based on the fines content. © 2018, Springer International Publishing AG, part of Springer Nature.
Effects of soil parameters and moisture content on stiffness of unsaturated blended laterite using tri-axial tests for rural roads
(2011) George, V.; Nageshwar Rao, C.; Shivashankar, R.
Evaluation of subgrade strength and stiffness is essential in the design of pavements and construction of embankments for highways in order to ensure that roads perform their functions satisfactorily over a longer period. The grain size distribution and compaction moisture-content have an immense influence on the strength and stiffness of subgrades. Among the various laboratory tests for evaluation of shear strength parameters, and the modulus of elasticity of subgrades, the tri-axial test plays a major role in describing the geotechnical characteristics of the subgrade. This paper deals with an experimental investigation on unsaturated laterite soils blended with varying percentages of fines. It focuses on a study of the influence of various soil parameters on the stiffness and strength of soil samples compacted at optimum moisture content (OMC), at the drier side of OMC, and also at the wetter side of OMC, and the development of meaningful correlations. © 2011 CAFET-INNOVA TECHNICAL SOCIETY.
Electronic ticket machine data analytics for public bus transport planning
(2018) Cyril, A.; George, V.; Mulangi, R.H.
This paper investigates various aspects related to demand modeling and line-planning for bus transport systems based on data elicited from Electronic Ticket Machine (ETM). The ETM data has not been explored thoroughly for transportation planning although it is nowadays collected and compiled by public transport undertakings on a regular basis. The data used in the study is part of transactions on ticket sales by Kerala State Road Transport Corporation (KSRTC) maintained at 6 bus depots in Trivandrum city for the period between 2010 and 2013. The data collected through ETM is immensely huge with average monthly passenger transactions of approximately one million. The database can be audited and compiled to determine the passenger demand, operator's performance, and effectiveness of the service provided. It is possible to determine the origin-destination (OD) matrix of the bus commuters by querying the ETM database using a specially developed program in MATLAB�. The OD data will assist in travel demand modelling, decision-making, and formulation of strategies for future preplanning of the transit system. The work presented in this paper provides details on the block-diagram developed for the formulation of the programme, and a demonstration of its capabilities. In a similar manner, it is also possible to determine the link-volume in terms of passenger flow on the transit network using a specially developed program. Additionally, it is also possible to elicit details on the load-rate with information on boarding and alighting of passengers at bus stops in addition to performance-related statistical details can be elicited from the ETM database. It is proposed to develop MATLAB� based programs for the same. The work described herein also includes description on the use of the time-series approach in short-term demand forecasting. The present work proposes a number of analytical methods that can be employed to derive information from ETM data for travel demand modeling, and strategic and operational planning of public transport. � 2017 IEEE.
Electronic ticket machine data analytics for public bus transport planning
(Institute of Electrical and Electronics Engineers Inc., 2018) Cyril, A.; George, V.; Mulangi, R.H.
This paper investigates various aspects related to demand modeling and line-planning for bus transport systems based on data elicited from Electronic Ticket Machine (ETM). The ETM data has not been explored thoroughly for transportation planning although it is nowadays collected and compiled by public transport undertakings on a regular basis. The data used in the study is part of transactions on ticket sales by Kerala State Road Transport Corporation (KSRTC) maintained at 6 bus depots in Trivandrum city for the period between 2010 and 2013. The data collected through ETM is immensely huge with average monthly passenger transactions of approximately one million. The database can be audited and compiled to determine the passenger demand, operator's performance, and effectiveness of the service provided. It is possible to determine the origin-destination (OD) matrix of the bus commuters by querying the ETM database using a specially developed program in MATLABÂ®. The OD data will assist in travel demand modelling, decision-making, and formulation of strategies for future preplanning of the transit system. The work presented in this paper provides details on the block-diagram developed for the formulation of the programme, and a demonstration of its capabilities. In a similar manner, it is also possible to determine the link-volume in terms of passenger flow on the transit network using a specially developed program. Additionally, it is also possible to elicit details on the load-rate with information on boarding and alighting of passengers at bus stops in addition to performance-related statistical details can be elicited from the ETM database. It is proposed to develop MATLABÂ® based programs for the same. The work described herein also includes description on the use of the time-series approach in short-term demand forecasting. The present work proposes a number of analytical methods that can be employed to derive information from ETM data for travel demand modeling, and strategic and operational planning of public transport. Â© 2017 IEEE.
Establishing relationships for strength characteristics of lateritic soils with varying silt fractions
(CAFET INNOVA Technical Society 1-2-18/103, Mohini Mansion, Gagan Mahal Road, Domalguda, Hyderabad 500029, 2016) Kumar, A.; George, V.; Marathe, S.
Design and construction of highway embankments constitute a major component of highway engineering science. Poor sub-grade strength, overloading due to traffic loads, and seismic vibrations can cause distress to pavement sub-grades and embankments. Inadequate compaction and poor sub soil drainage, in addition to low bearing strength of soils cause failure of embankments especially in submersible regions. The present study is focused on performing investigations on the engineering properties of lateritic and lithomargic soils and the effect of fines on soil strength. Tests such as California Bearing Ratio (CBR), tests for unconfined compressive strength (UCS), and tri-axial tests are carried to study the strength behavior of soil on addition of lithomargic soils. Additionally, the development of regressions will help field engineers in estimating the value of the CBR based on simple laboratory experiments such as Unconfined Compression strength test, and the Triaxial test. © 2016 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.
Evaluating Public Transport Efficiency: A Cross-Regional SFA Approach
(Horizon Research Publishing, 2024) Praveen Kumar, P.; George, V.; Mulangi, R.H.; Khandri, A.S.
Bus-based public transport systems are considered to provide affordable means of transport to trip-makers in urban and rural areas. Consequently, public transport organizations are prone to losses since these agencies focus on providing mobility to people on commercially viable routes while providing accessibility and mobility to underdeveloped remote regions. The primary objective of this study was to effectively use a parametric approach, such as Stochastic Frontier Analysis (SFA), in the evaluation of the performance of public transport organizations operating in India. The present study employed nine key performance indicators (KPIs) to evaluate 31 State Road Transport Undertakings (SRTUs) in India over a period of seven years (2010-2017). The nine KPIs, such as total cost, staff, fleet, fuel, capacity-km, effective-km, passenger-km, revenue, and passengers carried, were used to develop three performance measurement categories: cost efficiency, cost-effectiveness, and service effectiveness. After developing 29 initial models, the best ones were selected based on Akaike's Information Criterion (AIC) and Bayesian Information Criteria (BIC), and performance evaluation of SRTUs was carried out with the SFA approach using the Cobb-Douglas production function. The study revealed that the top 25 percentile of best-performing SRTUs in terms of cost-efficiency were those serving rural areas with average efficiency scores higher than 0.7668. Similarly, in terms of cost-effectiveness, it was observed that the best-performing SRTUs comprised a mix of both rural and urban SRTUs with average efficiency scores higher than 0.9156. Also, in terms of service-effectiveness, the best-performing SRTUs included buses operated mainly in urban areas in addition to a few serving hilly and rural areas with average efficiency scores higher than 0.6509. The findings of this study provide insights into the performance of SRTUs in India and highlight the importance of using KPIs to evaluate and improve their performance. This study also demonstrates the effectiveness of using the SFA in the performance evaluation of public transport organizations, especially when the data related to the KPIs are partially inconsistent. This is due to the facility that permits the formulation of a production function that assists in identifying random errors, allowing the replacement of erroneous data. © 2024 by authors, all rights reserved.
Evaluation of properties of porous friction course mixes for different gyration levels
(2009) Suresha, S.N.; George, V.; Shankar, A.U.R.
Porous frictions courses (PFCs) are characterized by high percent air voids content, and are widely used as pavement surface drainage layers. This paper presents details on the laboratory investigation performed on evaluation of properties of PFC mixes using the Superpave gyratory compactor. It also, provides a brief review of the latest specifications related to standard practices for mix design and the uses of these mixes adopted by various agencies. Major differences were observed in the design gyrations (Ndesign) and the design aggregate gradations. In this study, six gradations (G) were investigated with binder contents (BCs) ranging between 4.0 and 5.0% by mass of the total mix, for various gyration levels (N). The effect of N, G, and BC on the volumetric properties, unaged abrasion loss, permeability, and the permanent deformation characteristics of PFC mixes were investigated. The experimental results were statistically analyzed to identify the major influencing factors and their significance. © 2009 ASCE.