THE WIP-PUSH-WAVE: A LEADING INDICATOR FOR PROJECT PRODUCTION CONTROL

Project management has traditionally depended on lagging indicators, such as the ‘Earned Value’, that provide retrospective feedback and support reactive decision-making. In contrast, leading indicators that monitor production conditions and enable proactive control have been proposed in the Lean Construction body of knowledge. Metrics such as Percent Plan Complete (PPC) and subsequent flow-based measures have advanced this shift toward assessing workflow reliability and production status rather than after-the-fact outcomes. This paper introduces the WIP-Push-Wave (WPW), a novel leading indicator that captures and visualizes the wave effect created as Work in Progress (WIP) accumulates and rolls forward across planning cycles. By quantifying the degree to which the planned WIP exceeds the demonstrated capability of the production system, the WPW reveals overload conditions as they emerge, allowing intervention before performance losses occur. We present a case study of a portfolio of 1,300 projects, demonstrating the recurring wave phenomenon where unfinished work rolls forward, inflating WIP and degrading performance. We interpret this pattern as a self-reinforcing feedback loop driven by overcommitment and optimism bias in planning, and propose that a balancing loop, grounded in production principles, is needed to break this cycle and prevent such waves from forming. The WPW enables managers to identify planning biases, guiding them to improve the planning process.