Safety was always a concern at Michigan, primarily due to the high speeds and Armco barriers. The steep banking and rough pavement was treacherous on equipment, leading to frequent suspension failures, tire failures, blown engines, and crashes, many severe. Attrition in races at Michigan was always high, particularly in the 500-mile events. Crashes at Michigan ended – or effectively led to the end of – the driving careers of Chip Ganassi, Emerson Fittipaldi, Héctor Rebaque and Danny Sullivan. Likewise Merle Bettenhausen, Derek Daly, A. J. Foyt, Al Unser Jr., Gordon Johncock, Mario Andretti and Bobby Rahal, among others, all suffered injuries from crashes. After a horrendous crash in 1980 which split his car in two, Tim Richmond soon after quit Indy car racing and switched to the NASCAR circuit.