The southbound I-680 Express Lane was the first High Occupancy Toll lane project implemented in northern California. It was opened to traffic in September, 2010. The Alameda County Transportation Commission prepared a “Before” study in 2009 prior to construction and an “After” study in 2013. The data collection conducted before and after implementation included traffic counts, travel time surveys using “floating car” GPS runs, manual counts of vehicle classification and occupancy, aerial photography and video recordings. Similar “before” and “after” data were also collected for a control corridor where no express lane was implemented. The comprehensive and detailed data collection provided for the evaluation of numerous performance measures to help evaluate the effectiveness of the Express Lane, including travel time, travel speeds, vehicle and person throughput, bottlenecks and queues, vehicle occupancy, level of service, transit ridership, safety and violations and enforcement. Key findings included increases in travel speed in the general purpose lanes, increases in total person throughput, reductions in system delay and changes in vehicle occupancy percentages.