The term projects is shorthand for changes to a simulation network. Generally, projects correspond to planned or proposed future network changes such as increasing the number of lanes on an existing link or adding a new one. Projects can also be network changes used for other purposes, such as evaluating several different approaches to an airport. Each approach could constitute a separate project, and would represent an alternate future scenario for airport access. Even though only one of the projects might ever be actually implemented, all would reside side-by-side in the Project Database.
The 2.11 Toolbox is essentially a tool for managing and manipulating projects. Once defined, arbitrary combinations of projects can be used to build a wide variety of different networks. For example, by limiting the projects included in your network to those certain to be built, you can create a limited funding scenario. By including a wider spectrum of projects, you can simulate the effects of the passage of a proposed highway bond. In the United States, projects are particularly useful for managing networks for TIP and RTP related work. Rather than attempting to maintain a dozen different networks, you can define your proposed road improvements as projects, maintain only one network, and create simulation networks as they are needed.
For technical information about the data structures used to store projects, please refer to The Project Database and Item Definitions for the Project Database.