Roundabouts are commonly used to regulate traffic at intersections, and their effectiveness depends on factors such as traffic volume, site conditions, and design features. This study is concentrated on Chandigarh, an important city in India as it serves as the capital of two neighbouring states, Haryana and Punjab. In Chandigarh, where most intersections are roundabouts, traffic congestion and smooth mobility have become significant issues, making it essential to manage and regulate traffic efficiently. The purpose of this study is to evaluate the effect of geometric improvements on the level of service (LOS) of roundabouts. The study focuses on two roundabouts at Vikas Marg, which were chosen specifically for their traffic congestion problems caused by the area's escalating traffic volume. The study uses AutoCAD to analyse the geometric features of the roundabouts and examines their viability with respect to IRC:65-(2017) and IRC:SP-41-(1994) guidelines. Based on the analysis of the existing roundabouts, the study proposes recommendations for their improvement, particularly in terms of their design features, to ensure better traffic flow. After implementing the proposed improvements, the study performs a before-and-after analysis using traffic simulation in VISSIM to evaluate the impact of these modifications on the LOS of the roundabouts. The findings of the study show that the proposed modifications significantly improve the LOS of roundabouts, indicating that they are effective in enhancing traffic flow. The study's results provide a useful framework for transportation engineers to enhance the traffic flow and reduce congestion in Chandigarh and other cities facing similar challenges. The abstract should summarize the contents of the paper in short terms, i.e. 150–250 words.

This study presents a comprehensive analysis of roundabout performance under mixed traffic conditions, focusing on various parameters influencing performance effectiveness. Field data from ten roundabouts in three Indian cities, including those with multiple approach lanes, were collected to assess geometric features and traffic characteristics. The study addressed factors such as heterogeneity, gap acceptance behavior, capacity estimation, and level of service (LOS) by adopting a structured, stepwise methodology. Three entry capacity models were developed using different approaches: empirical approach, approach based on gap acceptance behavior, and traffic simulation. A multiple regression-based nonlinear model based on the empirical approach emerged as the most suitable for estimating entry capacity under mixed traffic flow, offering a more robust alternative specifically to existing Highway Capacity Manual (HCM) and simulation models. The HCM model based on drivers' gap acceptance behavior underestimated the field capacity, whereas the Traffic in Cities Simulation Model (VISSIM) tended to overestimate it. Furthermore, the study introduces two sets of criteria for classifying LOS, based on average vehicle delay and degree of saturation levels. Compared with existing models, these criteria offer improved evaluations by addressing limitations observed in previous methodologies. Utilizing K-means clustering, LOS classification criteria were established that enhance the assessment of roundabout performance. Results demonstrated slight increases in the range of each LOS compared to existing models, with adjustments made to better reflect user experience and roundabout performance. By incorporating the study's recommendations, urban planners and engineers can optimize design parameters for new roundabouts and evaluate the performance of existing ones to enhance traffic management efficiency.

Subgrade soil permeability is essential for effective pavement drainage, directly influencing the durability of flexible pavements. The current research investigates how industrial wastes viz. brick kiln dust and pond ash can be utilized, for enhancing the permeability of the clay and sand subgrades. Various proportions (10

The Open Graded Friction Course (OGFC) asphalt mix is known for its uniform grading, predominantly containing single-sized coarse aggregates with minimal fines. It is typically applied in thin layers (around 20 mm) over impermeable road surfaces. OGFC offers notable advantages in regions with heavy rainfall, enhancing pavement surface infiltration capacity and lateral water drainage due to the underlying surface’s impermeability. However, challenges such as raveling and rutting have impacted the consistency of pavements using OGFC mixes. This study aims to mitigate raveling concerns by incorporating Polymer Modified Binder into OGFC mixes. Crumb Rubber (10, 15, 20 and 25

Evaluation of roundabout capacity holds significant importance because it directly affects the performance, safety, and environmental issues at the intersections. Several researchers have presented models for estimation of the entry capacity of roundabouts, but most of them have been limited to traffic conditions in developed countries having proper lane discipline, and upto single-lane and two-lane roundabouts only. There is dearth of such studies for developing countries, such as India, where traffic conditions are entirely different from developed countries. This study aims to evaluate the capacity of both single-lane and multilane roundabouts in handling different levels of heterogeneous traffic flow. Data were collected at 10 roundabouts spread across three Indian cities. All the roundabouts have different geometrical features and lane configurations, thereby ensuring the applicability of this study across different roundabouts. The formation of queues was used to indicate that the approach is operating at its maximum capacity. Four different models (linear regression model, non-linear regression model, VISSIM simulated model, and calibrated Highway Capacity Manual [HCM] model) were developed for each roundabout, and results were compared with the field capacity values. Careful consideration was given to statistical characteristics of the data and different statistical tests were conducted to evaluate the reliability of these models. A separate set of roundabouts was used to test and validate the models. Results reveal that a non-linear regression model, based on both the geometrical and traffic flow characteristics, outperforms all other models. Additionally, sensitivity analysis was performed to check the effect of various parameters on the roundabout capacity.

Sustainable infrastructure planning and construction methods are crucial measures for achieving an adaptable built environment. Amidst considerations of road construction, a critical yet often overlooked aspect is the availability of natural resources. Consequently, there is a pressing need to adopt proven techniques that minimize investment and reduce the dependency on raw materials. The utilization of recycled aggregates emerges as a pivotal step toward achieving sustainability in the road sector and effectively managing construction waste. The present study was undertaken to investigate the potential utilisation of recycled asphalt pavement (RAP) and processed construction & demolition (PCD) waste in the dense bituminous macadam (DBM) layer of flexible pavements. Two types of bitumen (VG-30 and CRMB-55) and three aggregate types (NA, RAP and PCD) were considered to prepare sustainable bituminous paving mixes comprising of maximum proportion of waste. In the present study, the investigation was divided into three components. The first component focused at evaluation of physical and other engineering properties of bitumen and aggregates utilised in the study. The second component dealt with preparation of bituminous mixes incorporating different proportions of NA, RAP and PCD aggregates on the basis of Marshall method of mix design in order to develop sustainable modified mix, having similar or improved Marshall parameters to that of control bituminous mix (with natural aggregate). And the third component covers the performance evaluation of control and modified bituminous mixes on the basis of indirect tensile strength test and moisture susceptibility tests. Finally, it was concluded that 71% waste (30%RAP and 41%PCD) and 63.5% waste (30%RAP and 33.5%PCD) can be replaced with natural aggregates when developed using VG-30 and CRMB-55 bitumen respectively.

The objective of the present study was to increase the strength and stiffness of silty clay and silty sand subgrades for building economic and sustainable asphalt pavements. Advanced cyclic load tri-axial (ACLT) and California bearing ratio (CBR) tests were performed to obtain the experimental and theoretical resilient modulus (MR) of the soil subgrades, respectively. In addition, the impact of the stabilization of the plasticity and compaction characteristics of the soil subgrades was determined. The insight into the mechanism of the stabilization was obtained by determining the mineralogical and microstructural properties of the stabilized soils through X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) tests, respectively. The combined inclusion of 20% brick kiln dust and 20% pond ash resulted in 186% increase in the CBR, 224% increase in the experimental MR, 96% increase in the theoretical MR, 2.07 times higher pavement service life, 23% savings in cost, and 28% reduction in the CO2 emissions associated with pavement construction. The enhancement in the CBR and MR of the soils was attributed to the increased inter-particle friction, improved particle size distribution in stabilized clay and sand, and a concurrent reduction in the plasticity of clay. The study highlights the real-world usage of the ACLT test to get the real MR of soil subgrade rather than the over-estimated theoretical MR. For precise estimation of MR from CBR, a correlation between CBR and experimental MR was established.

Despite the adoption of roundabouts in developing countries for traffic management and smooth flow, the concept of traffic heterogeneity management at these intersections is relatively unexplored. Estimating passenger car units (PCUs) for different vehicle types to homogenize traffic is a recognized approach worldwide. In this study, vehicles were classified into five categories to provide a meaningful context for the analysis. The study proposes a model to estimate PCU values for different vehicle types, specifically at roundabouts, after identifying the potential influencing factors. The study was based on data collected from 10 roundabouts in three Indian cities, having different physical and geometrical characteristics. The proposed method yielded PCU values that were partially comparable with existing standards. Comparisons with the Indian Highway Capacity Manual (Indo-HCM) revealed that this publication underestimated PCU values for two-wheelers and three-wheelers by 20% and 11% respectively, but overestimated PCU values for big cars and heavy vehicles by 9% and 12%, respectively. Method appropriateness was ascertained from the lack of prior assumptions made about traffic and geometrical characteristics. To prevent unnecessary re-estimation of PCU values across locations, the idea of a heterogeneity counter component (HCC) was proposed. The model was trained using cross validation on a dataset of seven roundabouts, and its performance was evaluated on a separate dataset using mean absolute percentage error. The relationship between PCUs and the geometrical features of roundabouts, and the effect of traffic characteristics on HCC were studied. The findings might be considered while revising relevant codes and manuals (e.g., IRC-65:2017, Indo-HCM).

Abstract In the Himalayan zone, snow is a crucial component of cryosphere for efficient use of water resource management. The major objective of this research paper is to analyse snow dynamics in the Beas River basin using MODIS satellite images from 2007-2018, thus revealing important insights into the region’s snow cover variability and its potential impacts on the hydrological cycle. In this paper, the snow cover area (SCA) analysis has been done for the Beas River basin from 2007-2018 using the 8-day improved snow cover product (version 6) Terra-aqua (MOYDGL06*) MODIS sensor images and ERA5 data for winter period i.e., November to April. During the time period, SCA in the region ranged from ~46% (Nov 2016) to ~92% (Feb 2015). SCA and total precipitation were found to be declining at rates of 2.5 km2 and 52.2 cm, respectively. While the average temperature has been rising from 2007 to 2013 at a pace of 0.14°C. Though, SCA decreased at a faster rate of 20.49 km2 and total precipitation decreased at a faster rate of 36.2 cm during 2013-2018. In contrast, the mean temperature increased at a higher rate (0.38 °C). The study finds that SCA and precipitation are falling at a faster rate during 2013-2018. The trend derived from satellite data analysis of SCA was found to be consistent with the climate parameters. The study suggests that climate change is likely a major factor contributing to the observed trends in SCA, total precipitation, and mean temperature. The study also notes that the observed SCA trend is consistent with climate parameters. The paper investigates the fluctuations in SCA from November to April.

Glaciers and snow are critical components of the hydrological cycle in the Himalayan region, and they play a vital role in river runoff. Therefore, it is crucial to monitor the glaciers and snow cover on a spatiotemporal basis to better understand the changes in their dynamics and their impact on river runoff. A significant amount of data is necessary to comprehend the dynamics of snow. Yet, the absence of weather stations in inaccessible locations and high elevation present multiple challenges for researchers through field surveys. However, the advancements made in remote sensing have become an effective tool for studying snow. In this article, the snow cover area (SCA) was analysed over the Beas River basin, Western Himalayas for the period 2003 to 2018. Moreover, its sensitivity towards temperature and precipitation was also analysed. To perform the analysis, two datasets, i.e., MODIS-based MOYDGL06 products for SCA estimation and the European Centre for Medium-Range Weather Forecasts (ECMWF) Atmospheric Reanalysis of the Global Climate (ERA5) for climate data were utilized. Results showed an average SCA of ~56% of its total area, with the highest annual SCA recorded in 2014 at ~61.84%. Conversely, the lowest annual SCA occurred in 2016, reaching ~49.2%. Notably, fluctuations in SCA are highly influenced by temperature, as evidenced by the strong connection between annual and seasonal SCA and temperature. The present study findings can have significant applications in fields such as water resource management, climate studies, and disaster management.

Reclaimed Asphalt Pavement (RAP) has gained significant attention in recent years as a sustainable alternative to natural aggregate in road construction. This study presents a comparison of the physical attributes of RAP and natural aggregate, with a focus on their potential use as base and subbase materials in flexible pavements. The physical attributes of RAP and natural aggregate were evaluated using standard laboratory tests, including particle size distribution, specific gravity, water absorption, impact value test, Los Angles Abrasion test, flakiness and elongation test. The research concluded that RAP is comparable to natural aggregate in terms of particle size distribution and bulk density but has lower water absorption, impact, and abrasion values. The results shows that RAP is almost 53% more tougher that natural aggregate when tested for Aggregated Impact test and 30% more harder than natural aggregate when compared by Los Angeles abrasion test. Also, heatmap was used to analyse the relationship between physical attributes of natural aggregate and reclaimed asphalt pavement which depicted 93% similarity The findings suggest that RAP has the potential to replace natural aggregate in flexible pavements, further study is required to determine its long-term performance and durability.

Critical gap (CG) estimation, while taking into consideration inconsistent driver behavior resulting from heterogeneous traffic conditions, is a tedious task. Several methods dealing with CG estimation have been developed in the past but limited research has been done in this regard for developing countries and there is a lot of scope to explore this field considering varying traffic conditions on the roads. In this study, the maximum likelihood method (MLM), one of the most prominent methods of determining CG, has been compared with two other methods developed for traffic conditions prevailing in India. These methods use different techniques for calculating the CG, such as minimization of absolute differences of gaps given by Ahmad et al., and minimization of square root of standard deviation of actual gap value from the predicted CG as per the Indian Highway Capacity Manual (Indo-HCM). This paper discusses the estimation of CG for five different categories of vehicles using these methods to counter the heterogeneity of traffic. Data has been collected on two urban multi-lane roundabouts in India. SOLVER in MS Excel is used to optimize the functions defined in all three methods. The results reveal that the method suggested by Ahmad et al. gives the most consistent results which are close to actual value when driver behavior is inconsistent. The other two methods are also reasonably consistent, with the method given in Indo-HCM being slightly better than MLM. Further, two-way ANOVA was applied to check the consistency of results.

The development of a new road has a variety of ramifications for the environment, using considerable quantity of materials and energy. Also, the cost of crude oil, which is the principal source of bituminous binder, has substantially grown in recent years. This has resulted to a rise in the overall price of bituminous blends. Developing innovative materials and technology to incorporate greener material, waste and recycled materials into the manufacturing cycle of bituminous mixes is a solution that enhances both sustainability and cost-efficiency of the bituminous pavement industries. Sustainable materials have increasingly been adopted in construction of roads nowadays because people are more concerned about its ramifications towards surroundings. However, people keep seeking to discover the most appropriate sustainable materials to be utilised in developing road pavement. In the current research, the two primary components of bituminous mixture i.e. bitumen and aggregates are focused and reviewed. Furthermore, the study presents a brief outline of several recycled materials which have been effectively used into bituminous layers of flexible pavement. Review findings suggest that the usage of secondary material not only offers an effective waste disposal approach but also minimise requirement for traditional material and lowers the total building cost. An effective and appropriate system of transportation is crucial for the development of any nation. The purpose of this review study is to establish the applicability and effectiveness of the waste material that has been used in the bituminous layers of flexible pavement.

The proportion of India’s population living in urban regions has climbed from 14 per cent at the time of Independence to roughly 31 per cent at now. Demand for housing and transportation infrastructure in metropolitan areas is also similarly expanding. Rising environmental challenges has enforced the stakeholder to utilize the construction and demolition waste with more efficacy in the road and other building construction. Incorporation of C&D waste for manufacturing of aggregates is a step towards efficient management and consumption of this material. This yet, takes appropriate attention when generating aggregates to maintain their efficiency in their usage as part of concrete and roadway pavements. These aggregates may be of two kinds namely Recycled Concrete Aggregate (RCA) and Recycled Aggregate (RA). Recycled aggregate is manufactured from demolition waste that may consist brick, concrete, tiles, glass etc. and RCA is obtained from concrete following mandatory processing. The purpose of this research is to analyse the morphological and physical properties of C&D waste. Also, the study covers the effective utilisation of this waste in the building sector along with its benefits and limits. Previous research have demonstrated that the usage of secondary sustainable material not only offer an effective waste disposal approach but also minimise demand for virgin material and lower overall building cost. Construction and demolition waste characteristics vary based upon nature of waste, strength attributes of original elements, age of the destroyed structure, etc. Hence each sample of processed C&D waste should be examined to identify its physical and engineering strength attributes before employing it in any road project. This study also presents an outline of functioning of C&D waste processing plant with the aid of schematic flowchart.

Coal-fired thermal power plants provide the majority of the electricity in India and generate two waste materials: fly ash and bottom ash. For their disposal, the coal ashes are blended with water and dumped in open and termed as pond ash. Bulk utilization of pond ash in construction may be a sustainable option to its disposal. Research has shown that pond ash possesses beneficial engineering properties and can be innovatively used to develop sustainable infrastructure. The present article reviews the important engineering properties of pond ash such as physical, chemical, mineralogical, microstructural and toxicity. The effect of pond ash on the strength, compaction and plasticity properties of the soils was reviewed to determine the potential to stabilize weak soils for use in sustainable pavement construction.

Resilient modulus (MR) is the critical input parameter for the characterization of pavement geo-materials subjected to repeated traffic loading. The effectiveness of a material in stabilizing soil for the subgrade layer of pavement is usually assessed by MR estimated from quasi-static tests (California bearing ratio and unconfined compression strength), but these tests are not the accurate representation of repeated traffic loading, and hence the MR must be determined through laboratory cyclic triaxial test. This review examined more than 35 research papers published over the period 1995 to 2019 and identified 15 stabilizers that have been tested for soil stabilization under cyclic triaxial loading. The analysis of these articles highlights three different categories of stabilizers: first, waste materials such as fly ash, cement kiln dust, oil shale ash ground granulated blast furnace slag, dolime, bottom ash and lignin, second, chemical stabilizers such as lime, cement, lignosulfonate, sodium alginate bio-polymer and an ionic soil stabilizer and third, fibres such as polypropylene and lignin. The soils subjected to the test were organic clay and inorganic soils such as clay, sand, gravel containing soil and black cotton soil. The present paper discusses the effect of confining stress, cyclic deviator stress, number of load applications, curing period and dosage of the stabilizer on the MR of the stabilized soils. The analyses of these articles help understand the importance of cyclic triaxial test for proper characterization of stabilized soils for use in pavement construction. The fact that only a limited number of stabilizers for the soil has been studied so far, this review identifies a scope of determining the MR of materials that are potential soil stabilizers for future research.

Fibre-reinforced soil performs similar to a blended material composite wherein randomly oriented fibres are implanted in a soil mass. The focus of the current work was to review the performance of polyester fibre on the strength, stiffness and compaction parameters of soils. Research reported in literature shows that the inclusion of polyester fibre improves the bearing strength, optimum moisture content, unconfined compressive strength and split tensile strength, and mitigates maximum dry density of soil. The key factors controlling the performance of fibre-reinforced soil are concentration of fibres, material, orientation and distribution of the fibre. It was understood that natural and cement stabilized soils characterize brittle failure, leading to catastrophic results, and the performance of fibre in imparting ductility to brittle soils was highlighted. Enhanced strength characteristics of the soil-forming the subgrade are expected to reduce the required thickness of bituminous and granular layers, leading to sustainable construction.

Bricks are the primary building blocks used for construction. During the brick manufacturing process, combustion of coal and wood leaves behind brick kiln dust—a blend of coal ash, burnt soil, wood ash and brickbats. The waste is disposed off in open areas, engaging expensive land and contaminating of soil and groundwater. Mass application of the waste in construction applications is a sustainable alternative to open disposal. The present paper reviews the important engineering characteristics of the waste such as physical, chemical, mineralogical, microstructural and toxicity. The effect of the waste on compaction, strength and stiffness of soils was reviewed. Other innovative areas of research for successful application of the waste were reviewed. The analysis of literature helps in understanding the impending benefits of the waste in stabilizing weak soils for development of sustainable pavement infrastructure.