The “traffic and environment zone” around LondonÂ’s financial district has been extended to include the western part of the district. The zone limits the number of entry and exit points for traffic coming into the area known as “the City” and enables police to provide tight security, which has been high here since a string of IRA attacks in the 1980s. Security was increased following the Sept. 11 attacks in the U.S., and this current extension reflects a continuing concern with possible terrorist attacks.