Your description of a 7.5 earthquake along the Newport-Inglewood Fault ("The Bigger One," Nov. 29) provided a great deal of important information. However, Caltrans has studied the exact scenario you described, and far from "rain(ing) concrete chunks onto the surfaces below," overpasses in Central Los Angeles will stand largely undamaged. Some roadway settlement will occur, but the central freeway grid will remain largely in service. In the most recent Whittier earthquake, Caltrans crews inspected all 3,000 bridges in the Los Angeles area within a single eight-hour shift, and restored full traffic service to the one damaged structure within 21 hours.
Caltrans is now embarking on a $65-million program to apply what has been learned from recent earthquakes to strengthen bridge columns, generally lessening the threat of immobility during such emergencies.
LEO J. TROMBATORE, DIRECTOR OF TRANSPORTATION