Engineers and San Francisco Bay area politicians learned the lessons of the 1989 Loma Prieta earthquake. The 7.1-magnitude quake caused a 250-ton section of the Bay Bridge to collapse. The bridge reopened within a month, but the quake made it clear that the Bay Bridge required major repair or replacement in order to withstand the next major earthquake. Construction on a replacement for the eastern span began on January 29, 2002. The project is expected to be completed by 2013.