Society of Architectural Historians Annual Conference
Logical Flow: Critical Path Construction Scheduling in the 1960s
Conference Presentation, April 2019

Scheduling construction projects requires managerial expertise that contractors often lack and architects routinely spurn. This important pre-construction practice saw dramatic change in the 1960s with the emergence of the Critical Path Method (CPM). Still in use today, CPM was originally developed by the DuPont Corporation to schedule and estimate costs for complex research and development projects. It helps schedulers determine which tasks are most critical, thus making it easier to assess and respond to delays as they arise. Its primary innovation was a graphical system of task mapping called an arrow diagram. More than a mere schedule, these diagrams show the “logical flow” of a project. The eponymous critical path, traced from one key task to the next, reveals the total time expected to complete the project. By the mid-1960s general contractors, architects, and particularly construction managers had adopted CPM as an effective means to coordinate and schedule projects. The method’s computerization in the late 1960s quickly put architects on the outside looking in as numerical outputs replaced graphical. Absent arrow diagrams and with its capacity to visualize “logical flow” gone, interest in CPM waned among all but the most specialized project managers. CPM’s story raises important questions for an architectural history of pre-construction. To what extent do architects’ graphical sensibilities predispose them to view management tasks as unworthy of their attention? Is it logical or ludicrous that critical procedures like construction scheduling find themselves exiled from architectural practice?

Brochure advertising the services of McKee Berger Mansueto, Inc., a specialist in construction management using the Critical Path Method, ca. 1967.