Performance Analysis of a Hydronic Heating System for Frost Mitigation as a Sustainable Solution for Urban Infrastructure in Cold-Climate Regions: A Case Study of Tehran’s B9 Bridge

Objective:In cold and high-altitude urban environments, snow accumulation and surface icing represent critical threats to transportation safety, traffic continuity, and the long-term durability of bridge structures. Bridges are particularly vulnerable due to increased exposure to wind and lower surface temperatures compared to adjacent roadways. In Iran, snow and ice mitigation strategies are still largely reliant on conventional methods such as chemical spraying and sand spreading. While these approaches are widely used, they are associated with substantial environmental and structural drawbacks, including corrosion of reinforced concrete elements, contamination of soil and groundwater, and elevated maintenance demands. In this context, the present study aims to numerically evaluate the thermal performance of a hydronic surface heating system for snow melting on the B9 Bridge located on Artesh Highway in Tehran, which is currently equipped with a chemical-based anti-icing system. The objective is to assess the feasibility of replacing the existing system with a more energy-efficient and environmentally sustainable technology under cold-climate conditions.
Method: A transient thermal simulation was performed using COMSOL Multiphysics to model a hypothetical subsurface hydronic heating system embedded beneath the bridge pavement. The system consists of PEX-AL-PEX pipes circulating water at a constant temperature of approximately 40 °C. The numerical model incorporates conductive heat transfer through asphalt layers and insulation, as well as convective heat transfer associated with the internal water flow. Two representative winter scenarios were examined, corresponding to ambient air temperatures of −5 °C and −10 °C. For the more severe scenario, snowfall with an intensity of 30 mm/h was included to simulate realistic operational conditions. Temperature-dependent thermophysical properties of construction materials and the dynamic behavior of the circulating fluid were explicitly considered to ensure accurate representation of field conditions.
Results: The simulation results indicate that the hydronic heating system is capable of raising the pavement surface temperature above the freezing point within approximately 15–20 minutes under an ambient temperature of −10 °C. This thermal response is sufficient to effectively melt snow at a rate of 30 mm/h and prevent surface ice formation on the bridge deck. The total energy demand for one hour of continuous system operation was estimated to be approximately 851 kWh. Furthermore, an energy supply scenario demonstrated that the installation of 200 fixed photovoltaic panels, each with a nominal capacity of 700 W, could enable roughly 340 hours of system operation annually, highlighting the feasibility of integrating renewable energy sources.
Conclusions: Overall, the results confirm that hydronic surface heating systems offer a proactive, reliable, and environmentally responsible alternative to conventional chemical de-icing methods. Their ability to reduce chemical usage, enhance public safety, and integrate with renewable energy sources supports their application in sustainable urban infrastructure and climate-resilient transportation systems