Assessing future road safety with the advent of L-category quadricycles: Simulation insights from current crash patterns

Heavy quadricycles are gaining traction as sustainable urban mobility solutions due to their compact design, energy efficiency, and reduced environmental impact. However, their lightweight structure and limited safety features pose significant challenges in collisions, particularly with heavier traditional passenger cars. This study investigates the safety implications of introducing heavy quadricycles (L6e and L7e categories) into the circulating fleet, focusing on collision dynamics and occupant Injury Risk (IR). Advanced simulation tools are employed to reconstruct real-world impacts from an in-depth accident database and analyse the consequences of substituting traditional cars with L-category quadricycles. Velocity change (Δ𝑉 ) and IR are determined across various collision scenarios as a function of market penetration. Results indicate that in high-speed scenarios (90 km/h) L-category quadricycles experience substantially higher Δ𝑉 compared to traditional cars in similar collisions, leading to increased occupant loads and IR across the investigated collision scenarios. Conversely, in 50 km/h urban zones, the average fleet IR decreases, with Δ𝑉 averaging 12.6 km/h at 50% penetration. The safest environment is observed in 30 km/h cities, where IR decreases by over 50%. The findings suggest that current consumer programme tests may not fully capture certain critical collision scenarios for L-category quadricycles, notably side impacts. Consequently, further attention should be directed towards safety assessment protocols and design refinements that enhance crashworthiness without compromising the fundamental vehicle concept. The study concludes that while L-category quadricycles offer benefits for sustainable urban transportation, their integration requires careful management to address safety concerns, particularly in high-speed environments.