Resource levelling

A schedule computed with the critical path method assumes unlimited resources. In reality the site has a fixed number of carpenters, one tower crane or two concrete pumps. If several activities that need the same resource are scheduled at the same time, the resource histogram shows peaks above what is available, and the plan is not achievable. Resource management adjusts the schedule to match resources.

Resource smoothing moves non-critical activities within their float to flatten peaks and valleys, without changing the project finish. It gives steadier labour demand, which reduces hiring and idle time. Resource levelling goes further: when resources are strictly limited, it delays activities, even critical ones, until resources are free, so the project may take longer. The order in which competing activities get resources follows priority rules, such as least total float first, shortest duration first, or most successors first. Software automates this but planners must check the result, because levelling can create a new critical path driven by resources rather than logic.

Resource loading is the first step: assign resources and quantities to each activity. Productivity rates from past jobs make durations realistic. Histograms and cumulative resource curves show the plan. A smooth labour curve, rising to a plateau and tapering off, is a sign of a well-planned project; jagged peaks are a warning.