Optimization of signal timings for Diverging Diamond Interchanges
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A Diverging Diamond Interchange (DDI) is a relatively new design of interchange that has several advantages over the standard diamond interchange. Two of the most notable advantages of the DDI are an increased capacity for turning movements and a reduction in conflict point resulting in a safer intersection. Because this design is still in its infancy there are not established methodologies for dealing with the operations of the interchange. Most studies only offer a basic signal timing plan and phasing scheme which are not optimized for efficiency. Therefore, most state DOTs implementing a DDI choose to actuate the interchange and use a basic phasing scheme to optimize it in the field. This works great for off peak hours but causes delay during peak hours. This study applies a more efficient phasing scheme for this complex interchange and proves that optimization software such as Synchro can optimize the interchange with little loss in delay. As well as providing a range of volumes that the DDI can operate within and still be efficient. This approach to optimizing a DDI using Synchro was tested on the proposed location for the first DDI in Texas, located in North Austin at I-35 and RM-1431. The effectiveness of Synchro at optimizing the DDI is tested using Webster’s method of signal timing.