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Over the last two decades, there have been several studies on productivity related to transportation investments in not only Japan but also several foreign countries. However, these prior studies did not achieve common results as they did not use a unified format for measuring the service level of the transportation network and using the dataset. Therefore, this study classifies previous studies from six points of view. These are analytical method, functional type, explained variable, service level of the transportation network, aggregation level, and estimation method. This study examines the differences in results caused by the diversity of analytical methods. In addition, this study estimates the production function using two analytical methods with Japanese data. Then, the relationship between the productivity and transport investments is revealed. From this result, several issues are confirmed.

This paper develops a short-run economic damage assessment model. The model contains two sub models. One is the conventional traffic assignment model, which calculates traveling time under the damaged transportation infrastructure. The other is the economic damage assessment model, which determines the decrease in production level in the short run. This method facilitates the identification of critical infrastructure that could reduce the economic damage when the disaster occurs. As a case study, we applied this model to several recovery plans for transport facilities. The results suggest that the proposed comprehensive model should be considered as a prevention plan.

In this paper, regional financial computable general equilibrium (RFCGE) model was developed. The RFCGE model is a useful tool in the evaluation of regional fiscal policies. So far, computable general equilibrium (CGE) models have often been used to evaluate regional infrastructure investment policies. However, conventional CGE models do not consider financial assets, such as deposits, equities, and government bonds and decision-making mechanism of government. Therefore, applying CGE models might overestimate the benefit incidence of policies on the rural society. To confirm this theory, the RFCGE model was applied to regional infrastructure investment policy.

For contribution and primary distribution of television, i.e., television transmission to broadcasting stations, parallel transmission links that include codecs are often set up for reliability. However, this configuration still faces the following issues: 1) during normal periods, the reserve link is totally wasted and 2) when a failure occurs, the disrupted signal continues to be transmitted until the system switches to the reserve link. In addition, in digital video transmission, automatic assessment of received video quality is an important issue. To address these issues, the authors developed a processing system for parallelly transmitted video signals, which mainly consists of the following three elements: 1) when both links are normal, outputting the average signal of both links reduces compression coding noise and improves picture quality compared to only one link (efficiency); 2) comparison of the pictures from the two links enables failure detection in either link, to switch to the normal link (support of failure detection); and 3) comparison of the two normally decoded pictures enables evaluation of picture quality (automatic coding noise evaluation). This unique system improves the reliability and operational efficiency of conventional parallel video transmission links. Index Terms--Coding noise evaluation, efficiency, failure detection, parallel transmission, television transmission.