Limits to concurrency

In the global race to bring new products to market, many firms have adopted concurrent engineering as a technique to shrink development lead time. Due to the many concurrent engineering success stories in the business and eng ineering literature, a common misconception has grown that more concurrency is always better. The major contribution of this paper is a rigorous demon stration that limits to concurrency exist even in the simplified situation in which concurrency is modeled as the number of design modules to be execu ted in parallel. As complexities such as communication linkages between mod ules are layered onto our basic model, we show that the expected project co mpletion time is minimized at a finite number of modules, a number that dec reases with increasing problem complexity. In general, the more complex the project, the stricter the limits to concurrency. This strongly suggests th at project managers should be cognizant of the potentially adverse effects of pushing concurrency too far.