Myungsoon Chang

Realizing Benefits of Adaptive Signal Control at an Isolated Intersection

As with the advances in location-based technology that emerged from ecommerce and wireless communication, individual vehicular information is becoming available instantaneously and could be used for traffic signal control. A new paradigm of a signal control algorithm might be needed to accommodate such abundant location-based information. This preliminary study investigates the benefit of adaptive signal control under such conditions. A simple event-based simulation program along with a genetic algorithm-based signal optimization program developed in this study evaluates various scenarios including both demand and market penetration levels. A test bed used in the study consists of two one-way streets with single-lane approaches. This study provides a ceiling benchmark of adaptive signal control under perfect knowledge in vehicle arrivals. The results indicate that adaptive signal control outperforms pretimed signal control for all cases considered, but the marginal benefit of adaptive signal control increases up to a certain volume level and then decreases. The results also indicate that the use of imperfect knowledge improves performance of adaptive signal timing plans over pretimed timing plans.

Identifying Multiple Reasonable Alternative Routes: Efficient Vector Labeling Approach

An exact approach for identifying multiple reasonable paths in a transportation network is proposed. It is motivated by the deficiencies of heuristic approaches and K-shortest-path algorithms that have been used historically. The proposed algorithm is based on the so-called efficient vector labeling approach. The search space is pruned using a resource constraint. A route constraint is applied for maintaining the reasonableness of alternative routes. In addition, a dominance-checking concept is introduced to avoid identifying candidate subpaths at nodes that cannot satisfy travel time or route uniqueness requirements. The approach was demonstrated on a transportation network from Austin, Texas. It was found that the proposed algorithm can efficiently identify multiple reasonable alternative routes in transportation networks and has a number of advantages as compared with traditional K-shortest-path algorithms and heuristic approaches.

Analysis of Traffic Accident Characteristics for the Overlap Section of Horizontal and Vertical Alignment

This study has been conducted to characterize the relations between the accident rate and the overlap section elements where the horizontal alignment and vertical alignment are overlapped. The researches were performed on Horizontal curve sections of 4-lane highways with 100km/h of design speed and speed limit. Korea Highway Corporation`s Geographic Figurative Information System was adopted for geometric organization and Highway Traffic Accident Statistics was used. The results reveal that sections made of a single slope without vertical curve has greater accident rate than those with vertical curve, and that sections with 1 vertical curve are higher in the accident rate than those with over 2 vertical curve. For the sections with 1 vertical curve, SAG sections are higher than CREST sections and for the previous straight section of horizontal curve are higher than curved ones. In particular, when the road surface is wet, the accident rate is closely related with SAG vertical curves or leftward horizontal curved sections. This study will have meanings that it proposes the importance of design of road alignment by taking consideration of 3D synthetic alignment conditions for improvement of the road safety.

EVALUATIONS AND IMPROVEMENTS OF THE KOREAN HIGHWAY ELECTRONIC TOLL SYSTEM

In recent years, congestion pricing has gained popularity as a method for managing peak period congestion on major roads in urban areas. Especially, Intelligent Transportation Systems (ITS) technology has resulted in an electronic toll collection (ETC) system called “Hi-Pass” which is operated by the Korea Highway Corporation as a pilot program. Limited sections of highway have gained a good approval rating from motorists. In this research, the Korean highway toll system was analyzed with respect to the brief legal history of the toll road, collection method and levels. In addition, the electronic toll collection policy for foreign countries including France, Norway, and Italy are investigated. The toll system of each country is clearly differentiated with regard to the institution, regulation and the economy. After reviewing the pilot ETC program in Korea, the “Hi-Pass” system, several important factors were found. First, a more concrete marketing strategy for ETC users will be needed to encourage continued usage. Especially, frequent users and higher income users have more easily adopted the ETC system than others did. Second, in order to encourage the non-user to the ETC system, the costs of on-board units need to be reasonably low (about

Designing Pavement Marking for Hi-pass Lane Based on Kansei Engineering

50) and aggressive discounts (about 3–5% compared to 1% which are used currently) are needed.

Feedback Approach for Determining Parameters of Vehicle Safety Regulation on Pedestrian Protection: South Korean Case Study

Effective use of traffic marking can lead to driver`s safer driving by speed management and visibility enhancement. One of the critical factors in designing traffic marking is how to incorporate human factor issues into the design process. This study presented a methodology for evaluating the effectiveness of Hi-pass marking on Korean freeways based on kansei engineering. Hi-pass marking scenarios made by a virtual reality tool were used to evaluate the user`s perceptions. Various combination of chevron angles and peripheral transverse(PT) bars were used for the evaluation. The results show that the most effective scenario is a combination of 60 degree chevron angle and an askew parallelogramshaped PT bar shaped. It is expected that the proposed method and outcome will be useful for making safer driving maneuvers.

Development of an average green time estimation model for vehicle-gap based traffic operation

In recent years, significant efforts have been made around the world to establish an internationally agreed-upon vehicle safety regulation that will reduce pedestrian casualties in pedestrian-vehicle collisions. One of the key issues in putting together the regulation is how to select effectively the parameter values that will be associated with it. This study develops an integrated feedback-based decision-making procedure for determining parameter values of the vehicle safety regulation. The regulation aims to protect pedestrian heads in pedestrian-vehicle collisions. Detailed data analyses from both actual accidents and simulations were conducted to derive parameters that result in technically and economically feasible regulation. A set of parameters representing the characteristics of pedestrian accidents and vehicles in South Korea is presented as the outcome of this study. The major contribution of this study is in supporting the establishment of South Korean vehicle safety regulations that would lea...

TIMING TRAFFIC SIGNAL CHANGE INTERVALS BASED ON DRIVER BEHAVIOR

The Highway Capacity Manual (HCM) suggests estimating the average green time for performance evaluation of vehicle-gap based traffic operation and provides an average green time estimation model. This paper proposes a new model that overcomes the shortcomings of the HCM model. Through a comparison study based on 1,196 pieces of hypothetical test data, it was found that the average green times estimated by the proposed method yields a much better one-to-one linear relationship to the simulation data representing field data than that from the HCM method in both exclusive-only and shared-permitted cases. The R/sup 2/ values of the proposed and HCM methods with these cases are 0.90 and 0.86, and 0.56 and 0.57, respectively.