Additional problems persisted, and in 1993, high levels of lead were discovered near the bridge's towers. Further emergency repairs were undertaken in mid-1999 after small concrete shards began falling from the bridge into the East River. The concrete deck had been installed during the 1950s renovations and had a lifespan of about 60 years. The Park Row exit from the bridge's westbound lanes was closed as a safety measure after the September 11, 2001, attacks on the nearby World Trade Center. That section of Park Row had been closed off since it ran right underneath 1 Police Plaza, the headquarters of the New York City Police Department (NYPD). In early 2003, to save money on electricity, the NYCDOT turned off the bridge's "necklace lights" at night. They were turned back on later that year after several private entities made donations to fund the lights.