FULLERTON

Construction on the Highland Avenue underpass began this month, causing the closure of the street from Santa Fe Avenue to south of Walnut Avenue. The $6.6-million project, which is expected to take a year and a half, will lower Highland Avenue under a bridge being built to carry the five railroad lines. The project’s primary goal is to improve safety--as well as traffic flow--along the street that is traversed by 90 trains a day, said Bob Hodson, the city’s engineering director.