In construction scheduling, constraints among activities are vital as they govern the schedule solution. Understanding their criticality is essential for better schedule management. This paper presents a systematic method to classify and identify the criticality of schedule constraints for the schedule management from the constraint perspective. In terms of criticality, schedule constraints can be grouped into four types: project-critical, activity-critical, sequencecritical and non-critical. Project-critical constraints are those which govern start/finish time of critical activities and the project end time. Activity-critical constraints define the start/finish time of non-critical activities, and sequence-critical constraints are those whose existence affect the start/finish time of some activities or the project end time. Constraints belonging to any of these groups are vital to a schedule as they cannot be removed from the constraint collection. Noncritical constraints, on the other hand, do not govern either start/finish time of any activity or the project end time. Accordingly, non-critical constraints are redundant and can be removed from the constraint collection without causing any change to the schedule solution. The method proposed was applied to a illustrative case example based on the construction of the main entrance of a nursing house for further interpretation. The proposed classification scheme could shed light on a more in-depth understanding of the nature of criticality and the role of constraints in a schedule, and thus better schedule management may be achieved.

Thermoelastic stress analysis (TSA) has been around for the past 30 years, but to date, it is still a very much underrated and under‐utilised experimental technique. Although there are devoted groups of practitioners in some industries, this technology is not well known within the aerospace sector. In contrast, the Aerospace Division of the Defence Science and Technology Organisation (DSTO) in Australia has been in the forefront of this technology for some time, achieving many pioneering feats. This paper gives a brief introduction to the development of this technology from a historical perspective, then focuses on a number of innovations that have stemmed from DSTO, including the development and application of the world's first focal plane array based TSA system and, more recently, the development of small and robust microbolometer based systems. For the latter, it is shown that despite nominally poorer temperature sensitivities, they make ideal TSA devices and can in some cases outperform their much more expensive photon detector counterparts. Because of this, together with the enormous practical advantages of microbolometers, the future of TSA is shown to be brighter than ever. Specifically, it is argued that such TSA systems can play a major role in the pervasive and persistent surveillance of full scale fatigue testing of aircraft structures. By detecting both design and developing faults early, it can effectively relieve cost and schedule penalties that are often associated with unanticipated failures. To realise this capability, integration of this technology with autonomous systems will be important, and some preliminary but promising results from a technology demonstrator program are presented.

In construction scheduling, constraints among activities are vital as they govern the schedule solution. Understanding their criticality is essential for better schedule management. This paper presents a systematic method to identify and classify the criticality of schedule constraints for the schedule management from the constraint perspective. In terms of criticality, schedule constraints can be grouped into four types: project-critical, activity-critical, sequence-critical and non-critical. Project-critical constraints are those which govern start/finish time of critical activities and the project end time. Activity-critical constraints define the start/finish time of non-critical activities, and sequence-critical constraints are those whose existence affect the start/finish time of some activities or the project end time. Constraints belonging to any of these groups are vital to a schedule as they cannot be removed from the constraint collection. Non-critical constraints, on the other hand, do not govern either start/finish time of any activity or the project end time. Accordingly, non-critical constraints are redundant and can be removed from the constraint collection without causing any change to the schedule solution. The method proposed was applied to a case example for further interpretation. The proposed classification scheme could shed light on a more in-depth understanding of the nature of criticality and the role of constraints in a schedule, and thus better schedule management may be achieved.

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