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Sea space planning and congestion management is receiving more attention. However, little work on sea space capacity and strategy analyses can be found in the literature. Compared to other transportation systems, a sea space system has some special features that require consideration. The system capacity also depends on the pattern of traffic using the system. In this paper, we model a sea space as a directional network and capacity models for berthing areas, anchorage areas, fairways and their intersections, as well as the entire sea space system are developed. These models can be used to compute capacity for any given traffic pattern which can be extracted from vessel trip records or from traffic forecasts. To implement these models, a software system called Sea Space Capacity and Strategy Analysis System (SCSAS) has been developed in Visual C + + and is now being used in Singapore.

Energy costs and availability are major concerns in most parts of the world. Various measures to reduce energy consumption have been proposed. This paper focuses on two strategies to control aircraft ground operations as fuel conservation measures: operating fewer engines while taxiing, and towing aircraft between terminal area and runways. The potential benefits, costs, safety and operational issues related to implementation are investigated. As an illustration, the implementation of these strategies at ten major US airports is analyzed. About 278 million liters of jet fuel could potentially be saved from aircraft towing at these airports at their 1987 operation levels. However, there are some concerns related to towing which would make implementation unlikely until there is more urgency in fuel conservation. A more readily implementable strategy would be operating fewer engines while taxiing. About 88 million liters of fuel could potentially be conserved at these airports at 1987 operation levels.

The movement of aircraft in the terminal airspace is simulated using a fast‐time, critical events model. The model tracks the flight of each aircraft within the airspace studied and estimates aircraft delays within the terminal airspace. It also provides other relevant statistics such as controller workload, flow rates and travel times. The airspace model is capable of simulating a multi‐airport, multi‐sector environment. It incorporates logic that minics controller coordination and anticipation, and includes consideration of conflict resolution, aircraft speed control, overtake situation, aircraft holding and dynamic runway assignment. Operational data collected in the field were used in a model evaluation exercise. Results indicated that the model is capable of simulating real‐world aircraft operations in the terminal airspace.