One of the main problems designers had to face was anti-seismic features, given that western Greece was earthquake-prone. The chief concern was the possibility of the bridge collapsing in a strong quake. A thorough analysis showed large, shallow foundations were the most satisfactory solution, subject to the reinforcement of the top 20 meters of seabed subsoil, achieved by designing 90-meter-diameter pier bases and placing metallic inclusions in the subsoil. Thus the bridge can withstand a quake larger than 7 on the Richter scale, or the impact of a 180,000-ton tanker sailing at 18 knots, as well as winds of up to 250 kilometers an hour. It can also absorb a 2-meter displacement between any of its piers. The bridge consists of: – a 2,252-meter-long, four-pylon, cable-stayed bridge with a span distribution equal to 286 meters, 560 meters, 560 meters, 560 meters and 286 meters; – two approach viaducts, with 392 meters on the Rio side and 239 meters on Antirio side; – a 27.2-meter-wide deck with two lanes of traffic, one auxiliary lane and a sidewalk in each direction.