- Briefing Room
U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
Figure 4‑3 Vee Development Model
Highlights of the Vee Development Model:
A complete description of the Vee technical model is provided in Chapter 3.1.
The following development strategies are different ways that a project is implemented and deployed:
Single evolution Figure 4‑4. Single delivery; one single pass through the Vee
Incremental with single or multiple deliveries Figure 4‑5. Developing independent sub-systems and then integrating them together before delivery of a completed system is incremental with single delivery. Multiple developments of sub-systems that are integrated into an operational environment are called multiple deliveries deployment strategy. [See below for examples of each]
Evolutionary development Figure 4‑6. Developing sub-systems in a serial fashion as follows:
1. develop and deploy the servers, software, and communications
2. develop and deploy the workstations and software,
3. develop and deploy the field devices and software
One can mix and match these tactics into a hybrid approach such as an evolutionary development in which each evolution can be incremental with single or multiple deliveries.
The strategy selected for development is usually driven by one the following conditions:
The selection and tailoring of the strategy is done before or during the project planning phase. If funding is the driving factor, the agency may choose evolutionary development because of yearly funding increments. With large, complex projects, or the need to get the project deployed quickly, agencies may elect to use the incremental strategy. There, sub-systems are developed by different development teams and brought together.
Figure 4‑4 Single Evolution – Single Delivery
Brief commentary on single evolution- single delivery
This is not recommended for developments that can evolve over time.
Example ITS projects that may consider this strategy:
Figure 4‑5 Incremental Development with single and multiple deliveries
Brief commentary on incremental development with single or multiple deliveries
Example ITS projects for incremental development with single delivery strategy:
This strategy is used for systems or major sub-systems that need to be fully functional before being deployed into service.
Example ITS projects multiple delivery strategy:
Traffic signal system
Motorist information systems
This strategy is used when partial expansion of an existing system can be deployed over time. It should be noted that in the case of the multiple delivery strategy, the initial sub-system [in this example, the central management system for both the traffic control and motorist information system] needed to be fully functional. It needed to use the single delivery strategy and the expansion of the system elements followed by use of a multiple delivery strategy.
Figure 4‑6 Evolutionary development
Brief commentary on evolutionary development
Evolutionary development is recommended for ITS projects.
Example of ITS projects that may consider this strategy:
Incident Management System [single or multi-agency]
Sub-system 5-Incident Management Software
Regional Advanced Motorist Information System
Any projects that are done incrementally can be done using evolutionary deployment. In some cases, it may take several evolutions of development before it is ready to be commissioned into service. The interim evolutions would not be put into service until the whole system is completed. For example, a reversible lane control system may be implemented using evolutionary deployment but would not be commissioned into service until all essential sub-systems have been developed and integrated.