The research work described in this thesis is directed towards the development of simulation modelling methodologies for use as alternative construction-process modelling tools. Petri Nets (PNs), a general modelling method, are used as a basis for the development of the new systems. Prior to this, a validation of PNs within the construction context is performed by comparing PNs with both the Multiple Activity Chart method and the CYCLONE system. Once PNs have been established on pertinent to the construction context, two PN-based methodologies, Restricted Coloured Petri Nets (RCPNs) and construction-oriented modified Petri Nets (modified PNs), are developed. RCPNs utilise the concept of coloured tokens of Coloured Petri Nets (CPNs)--an extension of PNs which gives the modeller the capability to differentiate between different resource flows. Whilst maintaining the advantages of classical CPNs, RCPNs increase the ease of model development by eliminating the excessive mathematical components normally involved in the use of classical CPNs. In addition, the readability of graphical network models is significantly enhanced. As a result, RCPNs are easy to use for construction-process modelling. As well, they possess sufficient modelling power to represent dynamic and complex behaviours of typical construction processes. For some construction operations that are even more complicated, a more intricate methodology is sometimes required. In this research, modified PNs are developed to fulfil this requirement. Modified PN constructs, which consist of modelling elements, predefined attributes, user-defined attributes, control statements and reserved variables, enable the modelling of various characteristics typically found in construction processes. These characteristics include the dependency of activity durations, the overlapping of activities, delays, interruptions, optional and alternative queues, priority and multiple queuing-disciplines, complex resource routing schemes, resource selection schemes, limited available time of scarce resources and preventive maintenance. In conclusion, modified PNs are an alternative modelling methodology for the modelling of construction processes that are highly dynamic and complex.