Airport departure operations are a source of airline delays and passenger frustration. Excessive surface traffic is a cause of increased controller and pilot workload. It is also a source of increased emissions and delays, and it does not yield improved runway throughput. Leveraging the extensive past research on airport departure management, this paper explores the environmental and safety benefits that improved surveillance technologies can bring in the context of gate-or spot-release strategies. This paper shows that improved surveillance technologies can yield a 4%-6% reduction of the average number of aircraft on the taxiway system during congested operations, and therefore emissions, in addition to the savings currently observed by implementing threshold-based metering strategies under evaluation at Boston's Logan Airport and other busy airports during congested periods. These calculated benefits contrast sharply with our previous work, which relied on simplified airport ramp areas with a single departure spot and where fewer environmental and economic benefits of advanced surface surveillance systems could be established. Our work is illustrated by its application to New York's LaGuardia and Seattle-Tacoma airports in Washington.Index Terms-Airport departure operations, departure management, optimization, surface surveillance.