The RTA proposes to construct a railway overpass at Riverstone to improve road safety and the flow of vehicle traffic on Garfield Road across the railway line. The proposal seeks to separate road traffic from rail movements by providing a grade separated crossing of the railway line. The purpose of this preliminary environmental investigation is to i) identify and summarise the likely environmental constraints and issues that should be considered as part of an environmental impact assessment and approval prior to construction and ii) provide advice to guide the RTA in its consideration of whether the proposal should be assess under pat 3A, 4 or 5 of the NSW Environmental Planning and Assessment Act 1997