Non-Newtonian fluid speed bumps: A sustainable traffic calming review

In many developing countries, poorly designed and non-standardized speed bumps contribute to vehicle damage, passenger discomfort, traffic inefficiency, and delays in emergency services. Conventional rigid traffic calming devices apply uniform vertical deflection irrespective of vehicle speed, often resulting in excessive impact under mixed and high-density urban traffic conditions. This review examines non-Newtonian fluid (NNF)-based adaptive speed bumps as a speed-responsive alternative that exploits shear-thickening rheological behavior. A systematic review of 52 peer-reviewed studies published between 2000 and 2024 was conducted, focusing on the material rheology, comparative performance with conventional speed bumps, and feasibility of implementation in developing urban contexts. The reviewed literature indicates that NNF-based systems can achieve approximately 20%–45% of speed reduction for over-speeding vehicles while remaining compliant at lower speeds, thereby reducing unnecessary vehicle impact and improving the possibility of emergency vehicles. Reported lifecycle assessments suggest 30%–60% of potential cost savings over 7–10 years, primarily due to reduced maintenance demand and lower pavement deterioration. However, the performance is influenced by the material formulation, sealing durability, and temperature sensitivity, with reported viscosity variations of ±15%–30% under field conditions and the absence of standardized design guidelines. Overall, NNF-based adaptive speed bumps represent a promising yet context-dependent solution for sustainable urban traffic calming, requiring further long-term field validation and regulatory standardization.