The performance of four experimental cathodic protection systems durinq the first 8 months of operation is described. The systems were installed on the columns of the Burlington Bay Skyway Bridqe in 1982. The method of data collection and the essential features of the performance of each system are described. Macrocells and current pick-up probes were found to be the most useful tools for monitoring cathodic protection systems. The three impressedcurrent systems were all effective in stopping corrosion. Insufficient power was available from the galvanic system for it to be practical. The durability of some system components needs to be improved. The future work required to develop a fullscale operational cathodic protection system for bridge substructures is discussed.