This report discusses the design, construction, testing and evaluation of a bridge heating system that utilized ammonia heat pipes to extract energy from shallow well water and distribute it to condenser pipes near the deck surface. This efficient heat exchanger permits the Use of water as a heat source without the hazards of circulating it within the deck. Even though the well water temperature at Laramie, Wyo. was only 8°C, this system was able to reduce the snow cover time on a non-traffic lane by 72% relative to an unheated portion of the deck, and to prevent all preferential freezing of the deck relative to the adjacent highway. The steady state conductance between the water and the deck surface was approximately 15 W/m20C which implies that over 110 W/m2 was supplied by these units during a melting event. The ratio (COP) of the thermal power delivered to the deck's surface to the power required to pump the water from a 33 meter well, through the system, and then back into the ground was around 25. The use of an enhanced nucleate boiling surface should increase the above performance perimeters by approximately 35%. Since the COP increases linearly with water temperature, the Use of 12°C water, which is a typical value at lower northern elevations, would increase the above melting event heat flux and COP values by 50%. Continuously circulated fire hydrant water or a waste heat source in close proximity of a site represent some alternative sources to wells, while geothermal water supplied the thermal energy for a previous test