Exploring corridor operations in the vicinity of a diverging diamond interchange (DDI) : final report.

This research effort examined the corridor impacts of various signal timing and geometric strategies to improve the operational challenges observed at diverging diamond interchanges (DDIs). A microsimulation analysis was conducted using a calibrated and validated DDI modeled after the National Avenue and US-60 interchange in Springfield, Missouri. Four heavy volume scenarios were tested in combination with seven categories of strategies. These strategies were selected from a larger pool of strategies under the guidance of the North Carolina Department of Transportation (NCDOT) research panel and national expert recommendations. In addition to the microsimulation effort, a cost analysis was conducted for the same strategies. Considerations were made for implementation cost, disruption to user during implementation, and crash modification impacts. Finally, three sites in North Carolina were selected for field study. In the microsimulation analysis, those strategies which reduced the number of phases at the downstream adjacent intersection had the greatest benefit on the corridor routes for all four heavy volume scenarios. The reduction in phases reduced loss time and increased capacity for the intersection. Unfortunately, these strategies were also the most expensive alternatives studied, were likely to be the most disruptive to users during implementation.