Time-scaled logic diagrams are

A time-scaled logic diagram is a project schedule network diagram where the horizontal axis represents a calendar timeline. Activities are drawn as bars with their length proportional to their duration, and their placement along the axis corresponds to their calculated start and finish dates. This format combines the logical dependencies of a pure-logic diagram with the intuitive time-based visualization of a Gantt chart. It clearly shows the timing of activities, their logical ties, and the amount of float (often shown as a flexible line or different bar type) in relation to the calendar.

A. While computers greatly facilitate their creation, time-scaled diagrams can be, and historically were, drawn manually.
B. A pure-logic diagram shows only relationships; the length and position of lines have no temporal meaning. A time-scaled diagram is drawn to a calendar scale.
C. Calculating the most probable duration is a feature of estimation techniques like PERT, not a characteristic of how a logic diagram is drawn.

1. AACE International. (2016). Recommended Practice No. 10S-90: Cost Engineering Terminology. Defines "Logic Diagram, Time-Scaled" as "A logic diagram with a horizontal time scale. The activity symbols are plotted on the diagram at the time they are scheduled to occur." (p. 68).

2. East, E. W. (2016). Critical Path Method (CPM) Tutor for Construction Planning and Scheduling. University of Illinois at Urbana-Champaign. Chapter 3, "Schedule Visualization," distinguishes between pure logic diagrams and time-scaled network diagrams, noting the latter are "drawn so that the position of the activity reflects its schedule dates."