Investigation of production and schedule improvement methods for urban interchange reconstruction projects

This research was conducted to (1) analyze earthmoving productivity, (2) develop detailed schedules for urban interchange reconstruction for the Iowa Department of Transportation (Iowa DOT), and (3) determine whether expediting urban interchange construction is a possible solution for shortening duration for the reconstruction of Interstate 235 (I-235). The following projects were used as case studies in this research: (1) interchange reconstruction projects for the 14th Street, 19th Street, and 42nd Street in Des Moines, and 35th Street in West Des Moines. (2) bridge demolition projects for the 19th Street, Martin Luther King Street, and 42nd Street in Des Moines in the reconstruction of I-235. The analysis results based on site observation and statistical analysis were described in these case studies. In earthmoving analysis, factors influencing earthmoving production rates, such as bucket capacity, number of passes, and hauling distance in urban interchange construction were significant. For the scheduling part, the as-built schedules for 35 th Street in West Des Moines and 42nd Street in Des Moines were developed and compared with the contractor\u27s original schedule. The actual urban interchange construction schedule resulted in a later completion date than originally estimated by the contractors. Even if earthwork, utility work, and paving processes were expedited based on the as-built schedules, the activities could be expedited aggressively to reduce the construction duration more. Expedited urban interchange construction is an alternative method to reduce total duration of the I-235 corridor work. Moreover, duration, costs, resources, and sequences for urban bridge demolition were influenced by traffic control and bridge type

Development of a Wireless Real-Time Productivity Measurement System for Rapid Construction Operations

Existing on-site construction productivity measurement methods have some common limitations, such as the inability to provide data to engineers and project managers for real-time analyses and the difficulties of sharing data among participants involved in construction operations. To address these shortfalls, a wireless real-time productivity measurement (WRITE) system was developed. To validate the system, field experiments were conducted at highway and bridge construction sites. Statistical methods, such as the hypothesis test, the normality test, the paired t-test, and the Wilcoxon Signed Rank Test, were conducted to systematically analyze the experimental data. Results of the statistical analyses proved that the developed system generated identical productivity measurements compared to the stopwatch method, which is considered the classic productivity measurement method. In addition, a procedure to improve the on-site construction using the WRITE System and benchmarking technique was developed. The WRITE System has a potential to strengthen communication and coordination among participants involved in the infrastructure construction process by providing more accurate productivity information in real time

The China Great Leap Forward Famine: The Lasting Impact of Mothers’ Fetal Malnutrition on Their Offspring

Mothers born around the China Great Leap Forward Famine (famine-born mothers) are likely to have worse adult outcomes due to a negative relationship between fetal malnutrition and their health and cognitive ability. Using data from the China Health and Nutrition Survey, I investigate whether famine-born mothers transmit less human capital to their offspring through various channels, including less cognitive ability and other innate traits and by the choice of less investment in children’s human capital. My study also focuses on possible gender differences in these effects. I find that in-utero famine experience of famine-born mothers is negatively related to the education and labor outcomes of their offspring. However, female children are less affected by mothers’ famine experience than are men. This outcome suggests that Trivers-Willard (1973) effects dominate parental-choice effects despite the well-known son-preference of China.Gender difference, Malnutrition, Health, Labor Market Outcomes, Schooling, Barker hypothesis, Trivers-Willard hypothesis, China Famine

Development of a Wireless Real-Time Productivity Measurement System for Rapid Bridge Replacement

Increased attention has been paid to rapid bridge replacement, one of the critical components of the nation’s transportation network, since the terrorist attacks on September 11, 2001. To enhance the capability of rapid replacement of damaged bridges after extreme events, a prototype wireless real-time productivity measurement system has been developed. The developed system has a potential not only to improve the accuracy of construction schedule but also to strengthen the communication and coordination among parties involved in the replacement process after extreme events by providing accurate productivity information in real time. To validate the developed system, field experiments were conducted at three construction sites. Results of data analyses indicate that it is feasible to use the developed system to measure on-site productivity in real time; and productivity measurements were accurate and could be shared among all parties involved in the replacement process

Earthmoving Productivity in Urban Bridge Construction

Earthmoving operations in urban bridge reconstruction projects are analyzed to identify significant factors that impact relatively low productivity. The research project was conducted in the urban interchange reconstruction of Interstate Highway 235 (I-235) in Des Moines, Iowa. By using observational studies and a statistical analysis method, the factors were identified, including match factor, number of passes, and loading cycle time per bucket. Number of truck, match factor, travel time, and hauling distance were identified as the unique factors for the off-site earthmoving project, while the start time and travel time were significant factors for the on-site project. This research also identified significant factors for the truck bunching and showed that the match factor from the urban earthmoving project does not linearly correlate with the productivity of each truck. Reducing the hauling distance for urban earthmoving projects was the principal method for improving productivity

Does early access to pension wealth improve health?

Ministry of Education, Singapore under its Academic Research Funding Tier

The Lasting Impact of Mothers’ Fetal Malnutrition on Their Offspring: Evidence from the China Great Leap Forward Famine

We find that second-generation effects of in utero and early childhood malnutrition on the school participation of the offspring of mothers who experienced the China Great Leap Forward Famine.. The direct impact on entrance to senior high school is also negative, but smaller in magnitude than that on entrance to junior high school. Given that entering senior high school is contingent on completion of junior high school, the direct impact on entrance to senior high school obviously understates the total impact on the second generation’s accumulation of human capital. Our estimation results are generally robust to IV estimation.Malnutrition, Health, Schooling, Barker hypothesis, China Famine

Happy lottery winners and lottery-ticket bias

Ministry of Education, Singapore under its Academic Research Funding Tier