Stigmergy in Construction
There are few reported studies of stigmergy in construction. One researcher that has looked into the phenomenon in construction is the Danish researcher Lars Rune Christensen. Christensen has a background in information technology and seems to be biased towards computer-supported cooperative work (CSCW).
In construction, people might act upon the physical evidence of work previously accomplished by someone else (Christensen, 2014). When this way of working leads to coordinating the work tasks, stigmergy is recognised. This coordination of work is similar to the stigmergy of social insects. Not all aspects of stigmergy can be directly mapped to human practices, but most features are sustained. In the building process, stigmergy might be seen in the design phase, but also during the construction work.
Construction Design
The design of a building is done by architects and engineers. During design and planning, they make drawings and digital models to communicate the design (Christensen, 2008). Stigmergy can be recognised in the use of digital construction models where work on one submodel can be aligned to other models (Christensen, 2014). A design model is a combined model of the whole project. It is often divided into several submodels, or project models, each covering different contents. One project model might be of the structural framework, and another model might contain ventilation system design. Different people might concurrently work on different project models in their area of expertise (Christensen, 2014). The work process is distributed and allows independent work. All the distributed models are joined into the main construction design model. The design model contains details on all features of the construction. During the design process, this model will continuously be updated with newer versions of the submodels.
Model changes might lead to clashing components in submodels. Some BIM software has built-in clash detection, where clashes are detected based on pre-set requirements and limitations. When clashes are detected, designers strive to resolve them. A resolution might include a design change to conform with the design of other project models. The designers are aligning their models to the other submodels (Christensen, 2014). From aligning models, they achieve a better overall design in the construction model and prevent further clashes. Such model modifications are done based on work done by other designers. The design adjustments are made through communication embedded in the digital medium. Previous work acts as marks, guiding further work by people, like in stigmergy. The construction model is the digital medium where the stigmergic marks are left.
There are occasions where clashes or problems cannot be solved directly. In these cases, direct communication or meetings are required. However, by continuously aligning models to each other when possible, only occasional meetings are needed to coordinate the work (Christensen, 2014).
Clash detection in Naviswork
Construction Work
On a construction site, workers might follow up on the physical work previously done by someone else. Some tasks follow each other subsequently but involve workers from different fields of expertise. The different workers involved in these tasks might not work on-site at the same time. This results in little direct communication between them. An example would be a builder that build a steel frame for a wall. Next, the electrician arrives and installs the wiring based on how the steel frame is laid out. A third person might be responsible for doing the wall cladding and must adapt it to the existing work. Pieces of cladding must, for instance, be fitted around electricity sockets.
BIM models might not give all the detailed specifications for how the work should be performed. Plans and models are often underspecified (Christensen, 2014). The workers use their expertise to find solutions and fill in the missing work details. Since the workers are not necessarily meeting each other, some of the work might be based on the evident work previously done by others. If some of the building components are guiding the further work, the work might be subject to stigmergy. However, workers on the construction site do frequently communicate, and coordination through stigmergy is relatively rare.
Dual Environments
Digital stigmergy in the sense of peer production of software and encyclopedias is discussed in the section of Digital Stigmergy. All of the information related to a construction can be digital. This digital information can, for instance, be stored in a BIM, which means peer production might be applied to the digital modelling process.
During construction, a physical environment will evolve. Now, two environments are existing in parallel, partly inhabited by different actors. Stigmergic marks stimulating new actions might exist in both environments. Hence, both environments might be subject to stigmergy. The two environments can be distinguished by referring to the digital environment in a model as a medium.
The existence of two environments may give rise to problems due to discrepancies between the digital model and physical reality. At the current time point, there is not one preferred or optimal way of handling this. Some technologies do, however, have the potential of contributing towards a solution. The digital model could be used as an overlay to the physical construction, utilising Augmented Reality as seen in figure 8 (Krevelen, 2007). Another possibility is automatically updating the BIM to reflect reality. An updated model can be achieved through 3D scanning of the site, as demonstrated by Spets (2018).
