Transportation issues in metropolitan areas

For the last several decades, the concerns and issues of the transportation system in metropolitan areas have been changed as society and/or technologies do. Particularly, the advanced technology applications in transportation system planning and operation have become important for metropolitan areas around the world. This special issue on “Transportation Issues in Metropolitan Areas” is a collection of selected papers presented at the Biennial International Transportation Research Conference (BITRC) at the University of Seoul, Korea on September 3–5, 2009 and some other papers. The conference placed greater emphasis on discussions about the emerging issues of the transportation system in metropolitan areas. It brought together experts in planning and management of transit systems as well as scholars in advanced information technology applications in metropolitan traffic operations and management. In addition, experts in the area of accident analysis and freight transportation planning participated. The selected papers in this special issue cover wide spectrum of issues in metropolitan-related transportation studies from Asian countries and Canada. In July 2004, the Seoul metropolitan government reformed the public transport system in terms of routes, operations, and fare systems to improve efficiency and service levels of transit system. Since then, question to which extent the public transport reforms have led to improvements in efficiency and productivity has been raised. Oh and his colleagues empirically investigated the impacts of public transport reforms on efficiency and productivity growth both with and without accident costs in Seoul's bus industry. The bus operational data of years 2003 and 2005 were compared. They found that the overall productivity increased marginally regardless of the consideration of accident costs; it increased a little bit more with the consideration of accident costs. These results imply that the overall productivity at least did not decrease and the level of safety was improved by the public transportation reforms. Outsourcing in transit operation has an advantage of cost reduction in human resources; However, service quality issue due to the difficulty in securing professional railroads human resources has to be taken into account as well. The outsourcing in railroad operation in developed countries such as Japan and the United States of America is currently in operation for various reasons including better service quality, professionalism, diversity, work enhancement, cost reduction, etc. Ahn et al. compared and analyzed outsourced rail stations with non-outsourced ones in the ticket sales in terms of customer satisfaction in Seoul, Korea. From the field survey with railroad users, they found that customers were more satisfied with non-outsourced station than the outsourced one. However, they suggested that the factors which make this difference are needed to be further investigated. One of the Intelligent Transportation systems which have been extensively used in metropolitan areas around the world is Variable Message Signs (VMS). Lee et al. noticed that existing VMS are operated and managed by designers or operators without any consistent criteria on check up and replacement periods. They proposed a new framework to determine the optimal check up and replacement periods by analyzing cases in Seoul. The proposed method was designed to take into account Mean Time between Failure based on reliability engineering and visibility. It was found that the control parts should be checked every other week, power supplies every other month, monitors and communication parts twice a year, and cabinets every year. The optimal replacement of VMS was determined to be 10 years and the maximum replacement of VMS was 20 years. The optimal replacement of the LED in VMS was found to be 10 years when visibility of drivers is considered. There have been rich literatures among transportation engineers and urban planners regarding which type of street pattern should be recommended, particularly for new communities and developing communities. While the social benefits and drawbacks of different types of street patterns and urban forms have been discussed extensively in the literature, little attention has been devoted to the traffic safety evaluation of these street designs. Motivated by this fact, Rifaat et al. explored the effect of neighborhood street patterns on the severity of single-vehicle crashes. Using the crash injury data from the City of Calgary, logistic models were estimated for the years 2003–2005. They found that limited access street patterns are safer than the traditional grid-iron pattern but the effect is not significant. The marginal difference among community road types, they argued, results from the small difference in the speed limits. Density is the most important congestion indicator among fundamental traffic flow variables—flow, speed, and density. Measuring density by aerial monitoring, although accurate, cannot be widely used because of its cost and dependency on weather. The conventional method, estimating density based on the relationship between traffic flow and speed as measured by a point detector, does not yield an accurate density value, because in general the flow is not homogeneous. Lee et al. proposed a new method which overcomes this limitation. A new advanced density measurement method is based on the In–Out counting method. This method uses average density instead of instantaneous density. By using two point detectors, this method captures considerable variation in density. It was found that the proposed algorithm gave the results with the acceptable level of accuracy. Pattanamekar et al. studied freight transportation by evaluating the technical efficiency of shippers using data envelopment analysis (DEA) techniques. The data including 7365 shipping firms in Korea collected from the 2005 commodity flow survey were used in the analysis. Several DEA models were applied to determine efficiency scores based on both input- and output- orientations which include variable returns, constant returns, and non-increasing returns models. Accordingly, the technical and scale efficiency scores of each evaluated shipper in the same industry were measured and the best-practice firms for each industry were identified. It was found that in general Korean shipping firms are inefficient and too small relative to the optimal size with respect to their shipping activities.