Operational Advantages of Dynamic Reversible Left-Lane Control of Existing Signalized Diamond Interchanges

The signalized diamond interchange is a widely used intersection design for freeway-to-arterial connections. The capacity of these interchanges is largely determined by the number of lanes, the demands of the various movements, the storage spaces for different movements, and the signal-timing strategies. This paper studies the advantages of using dynamic reversible lanes for left-turn movements. In traditional diamond interchanges, the bay lengths cannot change; however, if signal times are adjusted to give more time to an approach when traffic counts are heavier in one direction (such as the shifts between morning and evening peak), this limitation in capacity can be mitigated. In this work, several diamond interchange designs are studied. The optimized traditional diamond interchange performance is compared, in simulation, to the proposed dynamic reversible lane case. Situations are identified in which a dynamic reversible left-lane control would be beneficial in reducing delay and increasing throughput for the interchange.