This article draws on an ethnography of road construction in the Peruvian Andes to explore how engineering projects operate as sites of contemporary governance. Focusing on the way in which engineering projects entail a confrontation with dangers of various kinds, we explore how people caught up in road construction processes become preoccupied with the problem of anticipated harm. Drawing on the notion of ‘codes of conduct’, we suggest that the governmental effects of practices which attempt to deal with the uncertainty (...) of the future might be analysed as a tension between the enactment of two different kinds of codification. Building on the notion of coding as a situated material practice, we investigate the appearance of two different ways of encoding a relationship with an uncertain future which we term ‘machinic’ and ‘emergent’. The article builds on a description of these two ways of encoding uncertainty to explore how formal mechanisms of dealing with anticipated harm, such as the regulations of health and safety, are both unsettled and reinvigorated by more affective and relational dimensions of practice. (shrink)