An Analysis of Habitual Mode Use in the Years of Rising Oil Prices

The existence of state dependence derived from panel data has played a very important role in studying employment and labor policies. This study is about state dependence of the transportation sector using retrospective panel survey data. The Ministry of Land, Infrastructure and Transport of Korea has conducted the survey to monitor changes in vehicle ownership and usage nationwide and to prepare measures when oil prices tend to rise sharply. From this data, we identify the existence of state dependence on passenger cars, public transportation, and nonmotorized modes. To do this, we estimate and analyze the dynamic random effects probit model that explains the selection of each transportation mode after controlling for the unobserved individual heterogeneity. Our results indicate that despite the rise of oil prices, behavior of habitual use (i.e., state dependence) of transportation modes is found in all three modes. The amount of state dependence of nonmotorized modes was the largest, followed by passenger cars and public transportation. From the estimated models, important policy implications can be drawn from the fact that the presence of state dependence and the importance of early habit formation are important not only in nonmotorized modes but also in public transportation. In other words, if policy makers want to encourage people to use public transportation in a new city, it suggests that a sufficient and convenient public transportation network should be built before people move to the city. Once cities are built without sufficient public transportation networks and people have become accustomed to using private cars, then it will be more difficult to change their transportation modes, requiring much more social efforts and costs. Document type: Articl

Commuting time stability: A test of a co-location hypothesis

During the past few decades, the populations of many US and European cities have shown the same residence and workplace mobility patterns: Annually, approximately 10% of the population changed residences and approximately 20% of employed workers changed workplaces within the same metropolitan area. Even though the Seattle metropolitan region experienced a substantial amount of residential and workplace mobility and a boom in employment and population in the 1990s, the morning commute time and distance was roughly constant. To explain this situation, researchers have proposed a co-location hypothesis, that is, residents and workers will change their residence or workplace or both adapt to worsening congestion. This research attempted to shed light on the mechanism of the co-location hypothesis using the Puget Sound Transportation Panel data consisting of seven waves of two consecutive years between 1989 and 1997 conducted by the Puget Sound Regional Council. Because most studies used cross-sectional work trip data to study location and commuting, the underlying relationship between location and commuting was limited. This study attempted to understand commuting patterns by residential and workplace changers. The study found that the commuting patterns of residence and workplace location changers were the same and this was reinforced by existing gravity model. Particularly, when workers change their locations, they prefer similar commuting zone (i.e., time and distance) compared to their previous commuting zone. These behaviors caused the average commute time and distance to be stable, regardless of high residence and workplace mobility, and the rapid growth of employment and population.

Estimating the Benefits of Korea’s Intercity Rail Speed Increase Project: An Agent-Based Model Approach

In the cost–benefit analysis of urban transportation investment, a logsum-based benefit calculation is widely used. However, it is rarely applied to inter-regional transportation. In this study, we applied a logsum-based approach to the calculation of benefits for high-speed projects for inter-regional railways in Korea’s long-term transportation plan. Moreover, we applied a behavioral model in which an agent travels beyond the zones assumed by an aggregate model. In the case of South Korea, such a model is important for determining transportation priorities: whether to specialize in mobility improvement by investing in a high-speed railway project, such as the 300 km/h Korea Train eXpress (KTX), or to improve existing facilities, such as by building a relatively slower railroad (150–250 km/h) to enhance existing mobility and accessibility. In this context, if a new, relatively slow railroad were constructed adjacent to a high-speed railroad, the benefits would be negligible since the reduction in travel time would not sufficiently reflect accessibility improvements. Therefore, this study proposes the use of aggregate and agent-based models to evaluate projects to improve intercity railway service and conduct a case study with the proposed new methodology. A logsum was selected to account for the benefits of passenger cars on semi-high-speed and high-speed railroads simultaneously since it has been widely used to estimate the benefits of new modes or relatively slow modes. To calculate the logsum, this study used input data from both the aggregate and individual agent-based models, and found that an analysis of the feasibility of inter-regional railroad investment was possible. Moreover, the agent-based model can also be applied to inter-regional analysis. The proposed methods are expected to enable a more comprehensive evaluation of the transport system. In the case of the agent-based model, it is suggested that further studies undertake more detailed scenario analysis and travel time estimation

Three-Dimensional Visualization System with Spatial Information for Navigation of Tele-Operated Robots

This study describes a three-dimensional visualization system with spatial information for the effective control of a tele-operated robot. The environmental visualization system for operating the robot is very important. The tele-operated robot performs tasks in a disaster area that is not accessible to humans. The visualization system should perform in real-time to cope with rapidly changing situations. The visualization system should also provide accurate and high-level information so that the tele-operator can make the right decisions. The proposed system consists of four fisheye cameras and a 360° laser scanner. When the robot moves to the unknown space, a spatial model is created using the spatial information data of the laser scanner, and a single-stitched image is created using four images from cameras and mapped in real-time. The visualized image contains the surrounding spatial information; hence, the tele-operator can not only grasp the surrounding space easily, but also knows the relative position of the robot in space. In addition, it provides various angles of view without moving the robot or sensor, thereby coping with various situations. The experimental results show that the proposed method has a more natural appearance than the conventional methods

Grant‐Aware Scheduling Algorithm for VOQ‐Based Input‐Buffered Packet Switches

In this paper, we propose a grant‐aware (GA) scheduling algorithm that can provide higher throughput and lower latency than a conventional dual round‐robin matching (DRRM) method. In our proposed GA algorithm, when an output receives requests from different inputs, the output not only sends a grant to the selected input, but also sends a grant indicator to all the other inputs to share the grant information. This allows the inputs to skip the granted outputs in their input arbiters in the next iteration. Simulation results using OPNET show that the proposed algorithm provides a maximum 3% higher throughput with approximately 31% less queuing delay than DRRM