Abstract. Instantaneous bridge failure tends to increase in Indonesia. To mitigate this condition, Indonesia's Bridge Management System (I-BMS) has been applied to continuously monitor the condition of bridges. However, I-BMS only implements visual inspection for maintenance priority of the bridge structure component instead of bridge structure system. This paper proposes a new bridge failure prediction model based on hybrid Markov-System Dynamic (MSD). System dynamic is used to represent the correlation among bridge structure components while Markov chain is used to calculate temporal probability of the bridge failure. Around 235 data of bridges in Indonesia were collected from Directorate of Bridge the Ministry of Public Works and Housing for calculating transition probability of the model. To validate the model, a medium span concrete bridge was used as a case study. The result shows that the proposed model can accurately predict the bridge condition. Besides predicting the probability of the bridge failure, this model can also be used as an early warning system for bridge monitoring activity.
The current tendering process has vulnerabilities that can be exploited to negatively impact project delivery. There are many research papers that discussed the occurrences of these exploitations (i.e., funds embezzlement, fraud invoicing, etc.), but there has not been one that focused on the study of the tendering process itself, nor presented problem analysis and mitigation options. The aims of this research are to identify and analyze problems in every stage of public tendering process, then offer potential solutions to resolve or curb these problems. In addition to utilizing publicly available studies and interviews were used as starting point of problems identifications. Questionnaires were then distributed to tendering practitioners. Likert scale assessment and factor analysis were used to measure the questionnaires and analyze the data respectively, while proposed solutions were established from experts’ judgement.This study showed that there are 135 problems that occur during tendering process. The most common problem is the bidding system’s inability to provide a complete database of contractors with their personnel, past works and experiences, and performance evaluation. The limited human resources in both number and competency is another important issue to consider. Proposed solution to solve these issues are based on four pillars of reformation concept done by public procurement agency.
The Circular Economy (CE) is a concept that aims to keep the value of products, materials, and resources economically as long as possible while minimizing the waste produced. The CE concept is adapted from the 3R principle (Reduce, Reuse and Recycle). The construction industry is one of the largest waste-producing industries. In fact, 30% of the waste in landfills is construction waste. This study aims to identify and analyze the application of circular economy in the construction industry in Indonesia. There are two main stages in this study. The first stage was to identify construction practitioners’ awareness of the circular economy. The second stage is to document the implementation of 3R on various types of construction projects such as building, road, and bridge projects. The questionnaire was used to collect data. Around 120 project managers of medium to large scale construction companies in Indonesia were used as respondents. Important Performance Analysis (IPA) is used to represent construction practitioner awareness of CE. The results show that most construction practitioners in Indonesia have understood the importance of construction waste treatment in the context of a circular economy. However, only a few construction companies that seriously take care of construction waste treatment. Most construction waste is only released to the landfill area through the third parties. Only about 36% of contractor reused and recycled waste is in the construction site.
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