Due to safety concerns with the 4.9 mile circuit, including the bumpy track surface and the inadequate barriers, deep ditches, and embankments, the last Formula One race held on the original Interlagos was in 1980, the race was nearly cancelled after protests by many Formula One drivers including defending world champion Jody Scheckter. The safety concerns were somewhat directed towards the track surface, which BBC commentator Murray Walker described as "appallingly bumpy". Most of the ground-effect cars of 1980 were designed in such a way that bumpy surfaces were barely tolerable for the drivers. These factors meant that Formula One would move back to the Jacarepaguá circuit in Rio de Janeiro, hometown of established star Nelson Piquet and where the Brazilian Grand Prix was held in 1978. After Formula One moved away, the only major race being held at Interlagos was the Mil Milhas Brasil, and the last major race on the original circuit was the 1989 Mil Milhas Brasil, and Formula One returned to the circuit the following year after it had been shortened and modified at a cost of $15 million. The track layout, aside from the pit exit being extended along the Curva do Sol over the years has remained the same since 1990. After the ascendancy of another São Paulo local, Ayrton Senna, negotiations were made to return to Interlagos that year, and it has stayed there ever since. The facilities include a kart circuit named after Senna. The circuit now also hosts the Brazilian Formula Three Championship.