Original: After the deaths of Senna and Roland Ratzenberger in Imola in 1994, the Estoril track was changed, with a new chicane built in place of the tank curve, as a security measure.
Simplified: After the deaths of Ayrton Senna and Roland Ratzenberger at Imola in 1994, the Estoril track was changed. A new chicane was built in place of the tank curve, as a safety measure.