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A pavement condition sensor aims to estimate the pavement surface grip, and therefore the sensor must detect the presence of water, snow, slush or the like on the surface of the pavement. The leading technology for such a sensor is near infrared diffuse reflectance spectroscopy using a wavelength range around a water absorption peak. In this paper we present a pavement condition sensor based on said technique that uses an electro-optic dual optical frequency comb generator as optical source. The proposed sensor provides unique properties in terms of measuring integration time that are necessary to advance the pavement condition several meters ahead of a moving vehicle. This work was supported by the Spanish Ministry of Economy, Industry and Competitiveness (grant TEC2017-86271-R) and by the Madrid Government (Comunidad de Madrid-Spain) under personnel Grant PEJ-2019-AI/IND-13093 and under the Multiannual Agreement with UC3M in the line of Excellence of University Professors (EPUC3M26), and in the context of the V PRICIT (Regional Programme of Research and Technological Innovation)

We report on an optical sensor for remote residual dry salt (NaCl) monitoring, with applications in road winter maintenance. The novelty of the sensing principle is the simultaneous measurement of the amplitude and decay time of the natural fluorescence of salt using synchronous detection. We present the characterisation of the luminous properties of salt that allow a sensor design with high sensitivity and stable measurements that match the requirements for the intended applications (concentrations below 20 g/m2). The proposed sensor system has a compact design and short response time, capable of being mounted on-board maintenance vehicles for real-time road condition assessment.