The rapid development of road infrastructure enhances connectivity and at the same time increases road crashes. A road traffic accident is one of the leading causes of injury and death in Nepal that has a great impact on the country’s economy. The identification of frequent road traffic crash spots and their causes are essential for the implementation of the most efficient countermeasures. Accident black spots are high-risk spots where numbers of accidents take place frequently and repeatedly. The study focused on the identification of black spots on the Mugling-Kotre section of the Prithivi highway of Nepal to provide knowledge for possible preventive measures for the improvement of road safety. The weighted severity index (WSI), prioritization index (PI), and focus group discussion have been performed to evaluate the safety status in the proposed area. The accident data were analyzed based on the weighted severity index (WSI), and the prioritization index (PI) was estimated by assigning a suitable weight to the factors contributing to an accident. Based on these results, six accident spots have been found critical regarding traffic safety. The result obtained from WSI and PI was further evaluated based on the focus group discussion so that essential safety measures could be implemented to enhance road safety.

Concrete, which is usually composed of cement, water, and fine and coarse aggregate, is the most dynamic building material for the construction of physical infrastructures because of its strength and durability, which solidifies over time in response to environmental changes. The size and shape of the aggregate have a significant impact on workability, strength, and durability of concrete since various particle sizes produce distinct reactions. To support the manufacturing of sustainable concrete, the research suggested substituting stone dust (SD) for sand. In contrast to the addition of stone dust, the application of superplasticizers improves the workability of concrete. The study aims to examine the compressive strength of M20-grade concrete that has superplasticizer added in addition to stone dust as fine aggregate replacement. The Maximum compressive strength of concrete has been achieved at 40% sand replacement. The findings revealed that the increase in stone dust content results in an increase in compressive strength of concrete using superplasticizer. The use of superplasticizer serves to increase the workability of the concrete and has no discernible effect on the compressive strength up to 50% sand replacement. The 28-days compressive strength achieved maximum value at 50% sand replacement with 2% superplasticizer. When stone dust and superplasticizer are added, the concrete becomes denser;conversely, when the amount of stone dust and superplasticizer is increased, the concrete becomes more slumped. For the construction of sustainable concrete, the SD can be used in place of fine aggregate in conjunction with superplasticizer.

Concrete is the most dynamic engineering material in construction due to its durability and strength properties, which have been used in almost all types of physical infrastructure construction. Crushed stone dust is a supplementary material that can be utilized to produce sustainable concrete. The concept of replacing natural fine aggregate in concrete production with stone dust (SD) could enhance the consumption of stone dust produced during aggregate production as well as reduce the requirement for landfill area for stone dust management. The study aims to compare the compressive strength of nominal mixed M₂₀ and M₂₅-grade concrete by replacing fine aggregates with stone dust. The results reveal that compressive strength increases with an increase in stone dust, but the rise in SD percentages beyond a certain level has a negative impact on the strength of concrete. However, fresh density has a similar trend of compressive strength, and the workability of concrete shows a declining trend with a rise in SD levels. From the results of the experimental investigations conducted, it is concluded that the SD can be used as a replacement for fine aggregate. It is found that 40% replacement of fine aggregate by SD gives a maximum compressive strength than normal M₂₀ and M₂₅ grade concrete, which starts decreasing beyond 40% replacement. The compressive strength of the concrete has been quantified by replacing sand with varying percentages of stone dust and found that it does not satisfy the specification except for 40% replacement for M₂₀ grade concrete, though it can be used for low and medium strength concrete production. The cost savings for M₂₀ and M₂₅-grade concrete at 40% sand replacement are 8.23% and 7.62%, respectively.

The structural properties of concrete, such as workability, strength, serviceability, and durability, are heavily influenced by the quality and characteristics of the aggregates used. The growing urbanization and infrastructure development have led to the overexploitation of natural aggregates, especially from the ecologically sensitive Chure region of Nepal, causing deforestation, habitat loss, and geomorphological instability. Meanwhile, construction and demolition waste continues to rise without effective reuse or regulation. This study addresses these challenges by evaluating the potential of Recycled Concrete Aggregates (RCA) as a sustainable alternative to Natural Aggregates (NA) for building applications. The research investigates and compares the physical (bulk density, specific gravity, water absorption, porosity), mechanical (aggregate crushing value, impact value), and chemical properties (alkali, chloride, sulfate, and carbonation content) of RCA and NA, following IS and ASTM standards. Assessing the physical, mechanical, and chemical properties of aggregates before concrete production is a critical step to ensure the quality, workability, strength, serviceability, and durability of the final concrete product. The results revealed that RCA has lower bulk density and specific gravity, and significantly higher porosity compared to NA. While both aggregate types met acceptable limits for water absorption and most chemical contents, RCA exceeded the 5% limit for carbonation, posing risks in reinforced concrete. RCA also displayed higher mechanical properties – Aggregate Crushing Value (33.64% average) and Aggregate Impact Value (30.40% average), making it unsuitable for wearing surfaces but acceptable for general concrete use. The findings suggest that RCA, despite its limitations in density, porosity, and carbonation resistance, is a viable and eco-friendly option for non-structural applications, pavements, and general concrete works. Its adoption can reduce reliance on quarrying, conserve the Chure ecosystem, and promote sustainable construction in Nepal. However, standardized guidelines and public awareness are essential to enhance its effective use and address associated environmental and technical concerns.

Maintaining the effectiveness of the transportation system is essential to economic growth. Poor road upgrading methods in many developing nations, however, are making it impossible for traffic to flow freely. Nepal developed the Nepal Rural Road Standards (NRRS) of 2055, District Transportation Master Plan (DTMP), and Municipality Transportation Master Plan (MTMP) to regulate the construction of rural road infrastructure. These guidelines provide guidelines for rural road planning, design, building, and maintenance, among other aspects. However, each geometric design has certain features, and parameter requirements depending on the region and location to be applied. This study aims to compare the geometrical features of the rural roads that have been built with the Nepal Rural Road Standards (NRRS) 2055, second revision (2071). Using a random sampling approach, six rural roads in the Morang district were selected for the data collection. To gather geometrical data, field observations and measurements were made at random chainages. This study evaluates various geometric parameters using linear and angular field measurements. Mapping conducted via smart road software ensures road geometry compliance, including aspects such as curve radius, shoulder width, gradient, sight distance, carriageway, and additional widening. The findings demonstrate that strict adherence to established standards substantially enhances road safety. Based on the results of the field observation, the geometric elements have been built according to design specifications, except for the additional widening at shoulder width and horizontal.