This paper shows how to simulate highway traffic flows using a Network-level Traffic Flow Model (NTFM) for both urban and motorway road networks. It highlights how road maintenance works can be modelled using a roadwork node in the network, and how the modelling can be used to predict the effects of maintenance works on the level of service of the highway network. In particular, the paper aims to show how the theory of vehicle flow fluctuation can be used within the roadwork node for better representation of reality while modelling road network flow. The NTFM is illustrated using traffic characteristics and road maintenance works on a motorway and trunk highway network in China. It is shown how the proposed method is useful in comparing worksite arrangements and describing the effects on flow rates due to roadworks.