The Guide to Road Design Part 4C: Interchanges provides road designers and other practitioners with guidance on the geometric design of freeway and motorway interchanges. However, the guide generally contains only advice that is specific to the design of interchanges and should therefore be used in conjunction with three other parts of the Guide to Road Design that relate to the design of intersections, namely: 1. Part 4: Intersections and Crossings General; 2. Part 4A: Unsignalised and Signalised Intersections; 3. Part 4B: Roundabouts. Part C covers design considerations, design process, forms of interchange, and provides some information on structures. However, designers should also refer to the Guide to Traffic Management Part 6: Intersections, Interchanges and Crossings which covers traffic management and road use aspects of interchange selection and design. The focus of this part is the detailed geometric design of the grade separations, ramps and ramp terminals associated with interchanges, particularly with respect to cross-section, design speed, sight distance, horizontal and vertical alignment, sight distance and the layouts of ramp terminals at the freeway and at the minor road. However, it also covers the needs of pedestrians and cyclists, and briefly covers some aspects relating to pavement markings, signs, landscaping and street furniture. (Author/publisher)
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