<p>Rockfalls are critical geological hazards that pose substantial risks to public safety and infrastructure, particularly in mountainous regions such as the Indian Himalayas. The present study examines a critically unstable slope along the Parwanoo–Solan section of the National Highway, which has been repeatedly affected by rockfall incidents. A detailed evaluation of the site was carried out, combining systematic field surveys, laboratory testing of rock properties, and numerical modeling using rockfall simulation techniques. The analysis aimed to estimate crucial rockfall parameters including bounce height, maximum run-out distance, kinetic energy, and block velocity. Results from the simulations indicate that rock blocks can attain bounce heights up to 3.4 m and kinetic energy levels exceeding 75.5 kJ. To mitigate these risks, re-engineered slope geometry along with the installation of a protective barrier system was proposed. The optimized design substantially reduces the maximum bounce height to 1.21 m and lowers the kinetic energy to approximately 65.7 kJ. A barrier structure with a minimum height of 2.0 m and an energy absorption capacity of 100 kJ was found to be technically sufficient to contain rockfall impacts and enhance the resilience of this critical transportation corridor.</p>