The supply of highway facilities in urban and suburban areas across South Korea has not kept pace with automobile growth, resulting in traffic congestion, and congested roads have contributed to worsen operation and safety problems with high fuel consumption. Traffic agencies and engineers in South Korea have focused on mitigating congestions through Intelligent Transportation Systems (ITS), demand managements, and other conventional measures. Unfortunately, these conventional countermeasures were exhausted in Korea to mitigate traffic congestion. From the viewpoint of efficiency and safety, a superstreet might be one of the alternatives to be considered for solving traffic problems. A superstreet is an unconventional intersection which redirects left turn and through movements from side streets. The design concept leads to increase safety by reducing conflict points at a major crossing point and operating like a pair of one-way streets which signals independently control from the both directions. Prior research have reviewed the performance of the implemented superstreets in North Carolina, U.S and showed a significant improvement in operation and safety compared to existing conventional intersection designs. The purpose of this paper is to provide insight on the potential to implement a superstreet as a promising solution for improving mobility and safety in the South Korea. This paper evaluated how a superstreet design effectively and safely handles with given traffic circumstances compared to an existing design. The VISSIM Model was selected to simulate the operations of subject intersections and Surrogate Safety Assessment Model (SSAM), developed by Federal Highway Administration (FHWA), which performs conflict analysis by processing vehicles trajectory data extracted from micro-simulations, was adopted to evaluate safety estimations. The results showed that the corridor with superstreets have the most effective progression of traffic along the entire road section with the fewest stops and lowest delays. Also it indicated that superstreets would contribute to have a decrease in collisions. The results would suffice to provide traffic agencies and engineers with an effective alternative to improve safety while reducing congestion.

This paper provides research results of a study to assess the driver performance levels of a 2+1 road, a special type of road involving intermediate cross section that is applied where a four-lane roadway construction is unjustifiable and the use of a two-lane road design may not provide the desired level of mobility. Despite increased driver safety, the use of the 2+1 road involves a problem that the South Korean government cannot assess the mobility effects of 2+1 roads, because the current Korean Highway Capacity Manual lacks the level of service procedure for 2+1 roads. Hence, research is required to provide potential measures of effectiveness for describing traffic flows in 2+1 roads and establish a reliable level of service analysis procedure. To address this issue, we applied the following approach: (1) existing research concerning 2+1 road design and flow performance was reviewed; (2) a field study was conducted in 2+1 roads with video cameras and traffic detectors to investigate traffic flow conditions; (3) candidate measures of effectiveness for describing traffic flow in 2+1 roads were identified based on field study results as well as TWOPAS simulation efforts; and (4) an analysis procedure applicable to determine levels of traffic flow service for 2+1 roads was proposed. We also examined how our proposed procedure would perform based on a case study. It was found that the percent time spent following would represent the most appropriate measures of effectiveness and that realistic output may be produced with our proposed procedure.