A study of the Route 161 corridor extending from the Flanders section of town to Main Street in Niantic reveals one of southeastern Connecticut’s busiest stretches, with traffic in the growing beach town threatening to get worse over time. A report on current and existing conditions administered by the Southeastern Connecticut Council of Governments (SCCOG) backed up what drivers already know: There is anything but a free flow of traffic in certain spots at certain times of day. The study is happening against the backdrop of a $142 million Interstate 95 project at exit 74 that went out to bid last week. Among the scheduled work is the replacement of the deteriorating Interstate 95 bridge to accommodate widening of Route 161 underneath and the addition of a new looping frontage road. Construction on the interchange could start as early as January, according to bid specifications. But while that state project will cover about a half-mile of Route 161, the regional corridor study takes a wider look.