THE DRIVER, RICHARD ROJAS, 26, WAS TAKEN INTO CUSTODY AFTER A TRAFFIC AGENT TACKLED HIM AS HE FLED FROM HIS CAR, A MAROON HONDA THAT CAME TO A STOP AFTER RAMMING INTO STANCHIONS AT THE CORNER OF 45TH STREET AND BROADWAY. The panic provoked by a car speeding on sidewalks in the heart of Manhattan immediately evoked the specter of terrorism, but law enforcement officials said they had determined that did not seem to have a role in the episode.