I'm not aware of major infrastructure projects implemented that have been chosen by social networks that are anarchist, then I'm not particularly aware of anarchism in peasant societies (and I expect that at least some large scale works have been performed there).***
In relation to industrial society, infrastructure was kept running as a social decision during Hungary 1956's general strike phase in November/December as a result of the decisions of the railway workers and hospital workers. These were "beg forgiveness" decisions. In the case of the railway workers, their partial labour was partially coerced by Soviet forces. In the case of hospital workers the reason to run hospitals during a bloody urban assault is pretty obvious.
Larger scale decision making has provisionally occurred by delegations of delegations during crises, but these have had limited impact and a common accusation is that they will tend to bureaucracy, even when effective recall is being exercised. The Central Workers Council of Greater Budapest called a ceasefire in November in cooperation with professional councils, and then attempted direct negotiation with Soviet forces. This council did not incorporate non-Budapest factory councils (except by telephone suggestion), and did not incorporate the generally more conservative geographic councils.
The answer is undetermined, the best examples are from the labour movement's self-organisation, particularly in revolutionary situations, particularly when the revolutionary situations involve factory councils. That these examples are tenuous, almost all involving revolutionary civil war; but, that there may be underexplored examples from peasant anarchism.
*** To cut short any discussion of free software authorship, the scale of these projects tends to involve human scale cooperatives producing freely and interlinking. This is not similar to constructing a transcontinental railway, or a system of shipping, or a water or power system.