Road and Bridge Heating Using Geothermal Energy. Overview and Examples

Abstract

Winter maintenance today is normally based on mechanical snow clearance together with the use of salt. The spreading of salt causes impacts on plants and the ground. Wintry traffic situations lead to reduced speeds, traffic jams and therefore to losses of time. New economical and environment-friendly solutions are needed in winter maintenance to increase road safety and mobility. Winter maintenance ?from the bottom? using renewable and free geothermal heat is an obvious solution and a chance to achieve these goals. Geothermally heated outside surfaces are typically based on hydronic heat exchanger installations in the pavement. The installed heating capacity depends on the climatic conditions and the system specifications. Snow melting needs higher system temperatures than simple prevention of ice-formation. Low system temperatures implicate an anticipatory operation control. A conceptual system design takes into account all relevant heat sources that are available in the neighbourhood of the planned road heating: e.g. natural hot water, ground-water or closed-circuit systems. A number of pilot plants for geothermal snow melting and/or geothermal de-icing have been built all over the world. A well known and well documented geothermal installation is the SERSO pilot plant in central Switzerland, which went 1994 into operation and is now still running. Geothermal road, bridge or outside surface heating is a feasible and approved possibility to increase traffic and public safety. Although the initial costs are high, such systems are not uneconomical. Social and macroeconomic benefits are given.