Models focusing on interactions between land-use and transportation mostly assume an exogenous provision of transportation infrastructures. We investigate here co-evolutionary processes between land-use and transportation, at the scale of Mega-City Regions, by introducing a toy model of corresponding processes. In particular, our model is specifically tailored to include governance processes ruling the growth of transportation infrastructure. We show through stylised numerical simulations the potentialities of our model to reproduce a variety of dynamics when co-evolution is taken into account. We then apply the model to a case study, by calibrating it for the Pearl River Delta Mega-city Region (China, 1990–2010). To go beyond this first modelling step, we elaborate on the challenges to overcome to go further towards more complex models integrating co-evolution between transportation networks and territories in urban systems.