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Economic analysis of mobility improvements
Published in Zongzhi Li, Transportation Asset Management, 2018
Unconventional intersections: The search for innovative methods to improve traffic channelization at intersections begins with assessing existing unconventional intersection designs. The existing designs have primarily focused on improving left-turn traffic movements to flow and safety. They can be classified into two broad categories: unconventional at-grade intersection designs and unconventional overpass/underpass and interchange designs. Typical unconventional at-grade intersection design options include doublewide, continuous flow, median U-turn, and superstreet intersections.
Platooning-based trajectory planning of connected and autonomous vehicles at superstreets
Published in Transportation Planning and Technology, 2022
Superstreet, also known as restricted crossing U-turn intersection, is one of the popular alternative intersection designs in the U.S. The superstreet design is meant to accommodate more traffic from the main street with compromise on the traffic from the minor road. The benefits of superstreet include sustaining greater left turn traffic volumes from arterials, reduction of conflict points, and smoother trajectories which decrease the emission and fuel consumption. Along with these benefits, superstreets also have some highlighted limitations such as greater construction costs and the potentiality of introducing confusion to drivers. Previous studies have proved the efficiency of superstreet, as summarized in Table 1. According to Table 1, it can be observed that superstreets can provide benefits in terms of traffic delays and safety in certain circumstances. Most of the existing studies on the performance of superstreet are simulation-based through PTV VISSIM or CORSIM.
A simulation study on the traffic delay and fuel consumption of connected and autonomous vehicles in superstreet with platooning, signal optimization, and trajectory planning
Published in Transportation Planning and Technology, 2023
Superstreet is one of the popular innovative intersection designs. It has superior performance compared to the conventional intersections in unbalanced traffic volume scenarios, which is often seen in the real world (Hummer et al. 2010). It is a variation of the median U-turn design, which guides left-turn vehicles from both the main street and minor street to travel through the intersection first and make a U-turn in a median opening that is usually situated hundreds of feet away from the main intersection. Superstreet differs from the median U-turn design in that left-turn vehicles from the main street can avoid making a U-turn by going through a dedicated channel to further increase the traffic efficiency for the main street (see Figure 1). Unlike the median U-turn design, through movement from the minor approaches in the superstreet also have to make the detour in the median opening to complete the trip. With such design, superstreet can increase road capacity and enhance safety due to the fewer number of phases and conflicting movements in each sub intersection of the superstreet environment (Hummer et al. 2010). Superstreet has been successfully implemented in numerous states in the US (Hummer et al. 2014) and researchers have also investigated the performances of superstreet in various aspects including safety, travel time, traffic delay, and so forth (Haley et al. 2011; Hummer et al. 2010; Naghawi 2014; Ott et al. 2015; Reid and Hummer 2001; Naghawi, AlSoud, and AlHadidi 2018; Hadidi, Naghawi, and Jadaan 2021). Conclusions can be made that the superstreet can outperform the equivalent conventional intersections in terms of average travel time or traffic delay.
Two-stage model for optimizing traffic signal control plans of signalized Superstreet
Published in Transportmetrica A: Transport Science, 2019
Liu Xu, Xianfeng Yang, Gang-Len Chang
Superstreet, also known as a restricted crossing U-turn intersection (RCUT), is a promising treatment with markedly lower rate of sideswipe, rear-ends and head-on collisions (Hummer 1998). Differing from a conventional intersection, Superstreet usually restricts the minor road left-turn and through movements to first make right turns, and then allow them to pursue the original directions following a directional U-turn. When signalized, this type of design can provide large, uninterrupted progression bands in both directions along an arterial of heavy traffic volumes. In addition, it only requires two-phase signal control plans which helps reducing intersections’ signal lost time.