Journal of Infrastructure Systems

There is a need to develop a calculation method to aid in the making of reliable predictions for the service life of bridge structures. This paper examines the basis for making service life predictions for existing reinforced concrete (RC) bridges in chloride-laden environments based on mathematical modeling. The corrosion process has two stages, the initiation time $\left(t_1\right)$ including depassivation time $\left(t_p\right)$ and the corrosion (propagation) time $\left(t_{\mathrm{cor}}\right)\text{.}$ The total service life of existing RC bridges can be expressed as $t=t_1+t_{\mathrm{cor}}\text{.}$ Many mathematical models were applied to calculate each $t_1$ and $t_{\mathrm{cor}}\text{.}$ The AJMF (2) and modified Bazant methods are suggested to estimate the values of $t_1$ and $t_{\mathrm{cor}}\text{,}$ respectively. The Chung-shan Bridge, 69 years old, in Taipei, was offered as an illustrative example for the modeling approach and service life predictions. The predicted results, such as B, E, F, and H zones, for the service life of the old Chung-shan Bridge using the proposed method showed that it is serviceable and reliable compared with measured damage. The results of this study were provided as a basis for repair, reinforcement, and demolition of existing RC bridges.

Current bridge deterioration models used in bridge management systems are not successful in capturing the effects of bridge condition history on future condition, in performing “what if” analyses for different maintenance scenarios, and in accounting for the interactive effects between deterioration mechanisms of different bridge components. Moreover, these models cannot be easily updated when new data is obtained. On the other hand, bridge management systems are updated on a regular basis and thus accumulate valuable knowledge about the performance of bridges over the years. The case-based reasoning (CBR) approach could reuse this knowledge efficiently to act as a deterioration model that would overcome some of the shortcomings of current models. A new CBR system, called case-based reasoning for modeling infrastructure deterioration, was developed and utilized in building a “proof of concept” application for modeling the deterioration of concrete bridge decks using data obtained from the Canadian Province of Quebec. The performance of the CBR model showed that CBR has great potentials in predicting the future condition of infrastructure facilities.

This paper measures the regional benefit of road investment in Korea, using the translog cost functions of the manufacturing industry for the four macroregions of Seoul Metropolitan Area, South-Eastern Area, South-Western Area, and Central Area. This paper shows that the road capital contributes significantly to the productivity of the manufacturing industry in the sense that the magnitude of the road capital stock elasticity of the production cost at the national level is $-0.0124\text{.}$ The net social rate of return for all regions is higher than the yield of corporate bonds, which implies that the road capital stock is undersupplied in Korea. The ratio of optimal to actual road capital stock declined from 1986 to 1991, and then increased in all regions except Seoul Metropolitan Area since 1992. In order to generate economic efficiency and regional equality, it is necessary to increase road capital investment in the less developed regions of Korea, such as the South-Western Area and the Central Area.

A transportation agency must consider the efficiency of its hurricane preparedness, response, and recovery operations. This paper develops and demonstrates a methodology to identify and characterize the schedule dependencies and subsequent delays that arise among federal, state, and local agencies and organizations involved in the pre and posthurricane processes in order to reduce the time for a region to recover from a natural disaster. The large scale of an agency’s overall recovery from a natural disaster presents a challenge to conventional scheduling models, including program evaluation and review technique and critical-path methods. A metanalysis to support agency resource allocation is thus developed as follows. Instances of schedule dependencies from past recoveries are collected and categorized according to the functional and organizational units of the agency. A categorical study is performed to highlight the functional units that are associated with the greater numbers of dependencies. The agency better understands which units need attention and which interfaces among units need improved coordination. The results of an example show that the interfaces of the Information Management unit and the Operations unit are sources of a significant portion of the dependency scenarios collected. The significance of the dependencies to the overall recovery is characterized in a multiattribute analysis. The analysis expresses the magnitude of a dependency in terms of its controllability, the involved agencies, resources involved, prevalence of similar scenarios, cascading effects, maturity, likelihood in the future, and severity in terms of its time duration. A transportation agency can use the developed methodology to identify, prioritize, and minimize the negative effects of schedule dependencies within and among agencies in recovery from a regionwide disaster. Recommendations are given to improve higher-level coordination both among the involved agencies and within the transportation agency.