Development and verification of an intelligent sensor system for roadway and bridge surface condition assessments

ABSTRACT DEVELOPMENT AND VERIFICATION OF AN INTELLIGENT SENSOR SYSTEM FOR ROADWAY AND BRIDGE SURFACE CONDITION ASSESSMENTS by Mohammed Aljuboori The University of Wisconsin-Milwaukee, 2014 Under the Supervision of Professor Habibollah Tabatabai Surface ice formation on roadways and bridges has been a major safety issue in transportation. Surface ice, or black ice, is a layer of frozen water that can form on roadway surface. Surface ice can form when moisture comes in contact with a pavement surface that is at a temperature below freezing. On bridges, surface ice formation tends to occur more rapidly because bridges are elevated, and are therefore subjected to air circulation both above and below the concrete slab. Each year hundreds of people die in road accidents related to surface ice in the United States alone. Hazards associated with surface ice presence are greatest in the Midwestern United States. In this thesis, an intelligent sensor system is developed for detection of surface ice on roads, runways, and bridges. The proposed sensor can also identify wet, dry, and frozen conditions. A decision algorithm is also developed that utilizes sensor output and measured surface temperature to determine surface conditions. The proposed sensor works by monitoring changes in electrical resistance between stainless steel poles embedded in the concrete sensor. The sensor consists of a 4-in-diameter, 1.5-in-high, concrete cylinder. The concrete cylinder includes an opening on its bottom surface to house the electrical circuits, power supply, wireless transmission unit, surface temperature sensor, and electrical controller that implements the decision algorithm. Two sets of poles (two LUS poles and two LU poles) are embedded at a distance of 2 inches between them. The LUS poles are sensitive to both above-surface and near-surface conditions. LU poles are only sensitive to changes directly above the sensor's top surface. Resistance changes are measured using two Wheatstone bridge circuits. A serious of laboratory experiments were performed on two sensor prototypes. The experimental results indicated that the proposed intelligent sensor can effectively detect various environmental conditions of interest including surface ice and wet conditions. The sensor output can be transmitted wirelessly to activate side warnings (lights/sounds/messages), or signals can be relayed to a website, transportation control center, maintenance crews, or control systems in vehicles.