GUILDERLAND — Finished is a $3.1 million roundabout at Crossgates Mall, the latest development in the Capital District Transportation Authority’s 8.5-mile-long express route project traversing Albany County’s urban core.Construction began in late April. The project included repaving, landscaping and traffic signal upgrades near the Interstate 87 ramp, requiring construction crews to down portions of the busy road within a three-month window.Crossgates Mall is one of CDTA’s highest volume traffic stops.The downtown Albany-to-Guilderland Purple Line is slated to launch in November, according to CDTA. Among more than 50,000 people residing within less than a mile of the route, many are believed…