The Operation of an Electrical Heating System for Bridge Decks

Abstract

The 9th-Street interchange with I 64 in louisville, Kentucky, was designed and constructed with an automated electrical heating system for snow and ice removal. This report summarizes the operation of the h eating system during the first four years. The system was capable of kee ping the interchange free of ice and snow accumulation. The average daily slab temperature fell below 0°C (32° F) only on a few occasions. The average cost of electrical power for heating the interchange was $883 per day, INTRODUCTION The presence of snow or ice on highways, especially at bridges and interchanges, often results in hazardous driving conditions. Conventional snow and ice removal may prove inadequate due to the time lag between ice and snow accumulation and plowing and(or) salting operations. Also, deterioration of concrete in bridge decks is often attributed to the use of deicing chemicals. A number of nonchemical methods of preventing freezing have been investigated. One solution for the control of such conditons is a heating system for bridge decks and pavements capable of melting any snow or ice that might accumulate on the roadway. The 9th-Street interchange In Louisville, Kentucky, is subject to extreme conditions dL!e to the use of maximum interstate grades and superelevations, the height of the ramps, and the location near the Ohio River (Figure 1). The major portions of the ramps are elevated, exposing both the top and bottom surfaces of the ramps to wind currents. An auto, mated heating system, with manual override switches, was deemed necessary for this location. The design, construction, and Initial oper!ltion of the system w~s described in o report to the Second lnternation~l Symposium on Snow Removal <md Ice Control ReseiJrch in 1978 (1), The heating system is operated at a low level of heat when the slab tarnperaturG goes above a certain set [loint. As the temperature drops, slab templlrature sensors Gause the voltage regulator t.o increase the voltage into the system. As the temperature increases, ·the voltage level is reduced. However, various weather parameters, such al November 16, 1978, to March 29, 1979; and November 13, 1979, to March 31, 1980. These periods included some