Browsing by Author "Mohan, Mithun"

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Analysis and Prediction of Road Accident Cost
(National Institute of Technology Karnataka, Surathkal, 2024) P H, Sumayya Naznin; Ravi Shankar, A. U.; Mohan, Mithun
Road traffic accidents (RTAs) significantly impact a country's economic advancement by consuming a large portion of its Gross Domestic Product (GDP), especially in developing countries. The proportionality of road accidents with urbanization mandates road accident cost analysis as a prime component in the planning and designing of road projects. The quantification of accidents and their associated parameters remains challenging, as it demands a meticulous approach. Moreover, allocation towards road safety infrastructure should be based on a cost-benefit analysis to ensure the most efficient use of available resources in formulating road safety policies, reinforcing the significance of road accident cost estimation. Different countries use varying methodologies for this estimation, rendering international comparisons unreliable. Notably, the existing methodologies mainly focus on developed countries, leaving a gap in the literature for developing nations. Human Capital (HC) and Willingness to Pay (WTP) are two commonly used approaches for estimating accident costs. The HC method, using diverse data sources such as police accident databases, questionnaire surveys, private hospital records, and vehicle garage bills (considering collision types), provides a component-wise breakdown of costs. The RTA cost estimation using the HC method reveals the loss of productivity, accounting for 49% of total costs, as the most significant component. Medical costs comprised 24%, vehicle damage 10%, human costs 16%, and administrative costs accounted for a mere 1%. However, this method overlooks intangible factors like pain, grief, and suffering (PGS) along with the contribution of post-retirement victims and caregivers of RTA victims. In contrast, the WTP-stated preference methodologies, Contingent Valuation (CV), and Discrete Choice Experiments (DCE) used in this study provide insight into the intangible costs, although with varying degrees of accuracy. Notably, WTP-CV estimates tend to have a lower bound, whereas WTP-DCE estimates are substantially higher. WTP-CV payment card approach reveals that accident costs are mostly influenced by population and risk reduction, with socioeconomic factors and driving behaviour also playing a major role. Meanwhile, the WTP-DCE method indicates that travel attributes have a greater impact on WTP than socioeconomic factors. Taking into account the limitations of both HC and WTP, a Hybrid method is proposed. This approach modifies the conventional HC method by incorporating the concept of Value of Statistical Life (VSL) to account for intangibles such as PGS. It also acknowledges the contributions of post-retirement victims and caregivers of RTA victims. The VSL concept, in conjunction with the Maximum Abbreviated Injury Scale (MAIS), enables a more comprehensive cost estimation, with PGS comprising 56% of total costs in the Hybrid method. In contrast, the productivity loss is reduced to 17%, ensuring the method is not solely focussed on lost productivity. Considering the nation's economic situation, using the weighted average method, the VSI for grievous and minor injuries was determined to be 19.4% and 3.6%, respectively, which can be implemented in regions with similar socioeconomic profiles. A Python-based program is developed, making this methodology more accessible and applicable. This tool can evaluate the severity of an accident, computing the resultant loss. A similar tool is also developed for calculating court-awarded compensations. The comparison results indicate that the cost and compensation differences are substantial and that compensation is typically less than the RTA cost, as it is predominantly based on the subjective judgment of the court. Using an expert opinion survey, the Hybrid method was adjudged as the best suited method for RTA cost estimation for accidents of different severity as more than 60% of the experts chose the RTA cost estimated using the Hybrid method over the other methods across various test scenarios. In conclusion, while the Hybrid methodology provides a more holistic perspective of accident costs, it still provides an estimate with a lower bound. This study does not consider some costs, such as infrastructure damage and traffic congestion. However, the approach highlights the imperative need to comprehend and estimate the true economic and intangible effects of road accidents, particularly in developing nations.
Effect of Warm Mix Asphalt Additives and Marginal Aggregates on Mechanical Properties of Semiflexible Asphalt Mixtures
(National Institute of Technology Karnataka, Surathkal, 2024) Doma, Hemanth Kumar; Ravi Shankar, A. U.; Mohan, Mithun
Semi-Flexible Asphalt (SFA) mixture is a wearing course in which Open-Graded Asphalt (OGA) mixes having air voids of 20-35% are grouted with cement mortar. In the present work, an effort was made to assess the effect of the Sand-Cement (S/C) ratio in determining the optimal grout proportions. Taguchi technique combined with Grey Relational Analysis (GRA) was used to obtain the optimal grout proportion. The optimum grout was obtained for an S/C ratio of 0.6, a water-to-cement (W/C) ratio of 0.40, and a polycarboxylic ether-based superplasticizer (SP) content of 0.75% by weight of cement. The SP content was identified as the most influencing factor, along with the S/C ratio. To investigate the effect of aggregate gradation and bitumen type on the mechanical properties of SFA mixtures, a new aggregate gradation with neat and modified bitumen was used to prepare OGA mixtures and later grouted with optimal grout proportion. The Marshall Stability, compressive strength, Indirect Tensile Strength, Cantabro loss, fatigue resistance, moisture and Oil spillage resistance tests were conducted. The results showed that the SFA mixtures prepared with Polymer- Modified Bitumen (PMB) and the new aggregate gradation have better mechanical properties, implying the significance of bitumen type and aggregate gradation. Due to the enormous generation of construction and demolition waste, processing and utilising recycled aggregates in pavement layers, particularly in asphalt layers, is deemed necessary to reduce the disposal problem and depletion of natural resources. Evaluating the performance of asphalt mixtures with recycled aggregates is complex due to the heterogeneity of materials. Therefore, the potential of utilizing the recycled aggregates in semi-flexible asphalt mixtures was explored along with the ferrochrome slag (FCS) aggregate. Though the FCS aggregates exhibited good mechanical and engineering properties, studies on the utilization of ferrochrome slag aggregate are limited. Therefore, in the next phase of this research, the Natural Coarse Aggregates (NCA) in OGA were replaced by Recycled Concrete Aggregates (RCA) (50% and 100%) and Ferrochrome Slag aggregate (FCS) (100%), and the effect on the mechanical properties of SFA mixtures were evaluated. The RCA was obtained by crushing the laboratory-prepared concrete specimens and passing them through the jaw crusher, followed by the ball-milling. SFA with 100% FCS exhibited higher stability, compressive strength, moisture resistance, fatigue life and rutting resistance due to strong aggregate having good impact value. At the same time, SFA with marginal aggregates (RCA and FCS) met the requirements of IRC SP 125. With the objective to reduce working temperatures of OGA mixtures, three Warm Mix Asphalt (WMA) additives, Sasobit (3%), Rediset (0.8%) and Zycotherm (0.1%), were added to PMB 40. The SFA mixtures prepared using WMA-modified binders were evaluated, and concluded that the SFA with Sasobit exhibited better mechanical properties than other mixtures, while the SFA with Rediset exhibited lower mechanical properties; however, all the SFA mixtures satisfied the specifications of IRC SP 125 2019. In the present study, a new approach, based on percentage coating, was adopted to determine working temperatures. The WMA additives reduced mixing and compaction temperatures by 30 oC and 28 - 33 oC. In the final phase, Semi-Flexible Asphalt (SFA) mixtures were prepared using marginal aggregates (50% RCA, 100% RCA, and 100% FCS) combined with WMAmodified binders. The incorporation of WMA additives allowed for a reduction in mixing and compaction temperatures by 25–35°C and 28–33°C, respectively. However, the mixtures 50RCA-R, 100RCA-S, 100RCA-R, and 100RCA-Z showed higher Cantabro weight loss, indicating lower durability, and were therefore excluded from further evaluation. The 100FCS-S mixture exhibited the highest fatigue life across all stress levels. The rut depth and DS results for SFA mixtures with FCS displayed similar values, emphasizing the significant influence of the aggregate quality or type. Only the mixtures 50RCA-S, 50%RCA-Z, 100FCS-S, 100FCS-R, and 100FCS-Z met the IRC requirements. Among these mixtures, SFA mixtures prepared with Sasobit additive and FCS aggregate performed better than other additives and marginal aggregates.