Performance of Transportation Infrastructure

Transportation infrastructure plays a key role in strengthening economic development opportunities while promoting a better quality of life. Funding challenges are always an issue. Transportation authorities are seeking design innovations, new materials, robust construction, and maintenance technologies to preserve and extend the life of transportation infrastructure because one of the primary objectives of transportation authorities is to provide safe transportation facilities for effective and efficient movement of people and goods. Any decision taken in the conception and construction stages has a significant economical and environmental impact. Consequently, cost reduction is always a key concern of researchers and practitioners worldwide. Cost reduction is not only measured by the reduction of initial costs, but by various other aspects, such as the application of appropriate procedures to increase the life cycle of a project, the use of sustainable materials, the optimization of maintenance strategies and the development of monitoring techniques. This special issue includes 11 peer-reviewed papers that were solicited by the organizing committee of the Geohunan International Conference 2011 from conference presenters. The Geohunan International Conference 2011 provided a showcase for recent developments and advances in design, materials, construction, and maintenance of transportation infrastructure. The conference offered a forum to discuss and debate future directions for the 21st century. It covered a broad array of contemporary issues for professionals involved in pavement, geotechnical, and bridge engineering. There are four papers in this special issue that discuss different aspects of pavement engineering. The first paper, by Steyn and Briedenhann, analyzes the poor performance of surfacing seals where the road is under a bridge. The authors found that because of the low temperature under the bridge during construction, rocks were lost due to smaller rock embedment depth. The authors propose to alleviate the problem by analyzing the potential decreases in surface temperatures during the planning phase and specifying localized increased compaction of the surfacing seal during construction. In recent years, transportation authorities and asphalt industries have explored warm-mix technologies as a means to reduce the mixing and compaction temperatures of asphalt such that energy consumption, emission, and air pollution can be reduced. In the second paper, Xiao, Amirkhanian, and Zhang present a comprehensive laboratory investigation to determine the influences of nonfoaming additives on asphalt binders. The authors found that nonfoaming additives can reduce the viscosity value of asphalt binders and thus decrease the mixing and compaction temperatures such that the performance of asphalt mixes is not sacrificed. Due to increasing traffic volume, and heavy axle loads, many highway pavements in China have premature failures before they reach the designed service life. The third paper, by Wei, Wang, and Ma, explores the perpetual pavements in China to last for 50 years without requiring major structural rehabilitation or reconstruction and needing only periodic surface renewal to address surface distresses. To calibrate and validate the authors’ concepts, the authors instrumented the perpetual pavement sections and compare the measured pavement responses under various axle loads and pavement temperatures to the theoretical model using Monte Carlo simulation techniques. Early or delayed joint sawing may cause either pavement raveling or random cracking. In addition, early opening of a pavement to traffic may also result in premature concrete deteriorations, while delayed opening of a section of pavement to traffic is costly. The fourth paper, by Ge, Wang, and Gao, applies an integrated model Finite Element Modeling Laboratory (FEMLAB, now called COMSOL Multiphysics) to optimize concrete mix design, select concrete placement temperature, and arrange paving time for the optimal concrete construction and strength development under specific environmental conditions. The following two papers are dedicated to soil influences on infrastructure performance. Problems related to loess soils or other unstable soils are highly correlated to climate. Techniques that reduce the vulnerability of soils are quite important. There are two common treatments to reinforce a soft foundation. One is enhancing the soil strength, for example, vacuum preloading and surcharge preloading. The other is installing structures with high stiffness into the soil. The paper by Yu and Yang presents a framework to correlate the cone penetration test (CPT) cone-tip resistance with the local shaft capacity of open-ended steel pipe pile in sand. Effort is made to develop a modified framework to correlate the soil-squeezing effect to the degree of soil plugging. Among the in situ tests, the cone penetration test has been preferably used in the development of the relationship between the cone resistance and pile capacity. Lv, Liu, Ding, and Kong investigate the performance of an X-section cast-in-place concrete (XCC) composite foundation based on the load-settlement curves, axial force and side friction distribution, pile-soil load sharing, pile-soil stress ratio, the sharing of side resistance and end bearing capacity by field tests on an XCC single-pile composite foundation. The authors found that the XCC pile can significantly increase ground bearing capacity. Landslides are often affected by climate. It is important to conduct theoretical studies regarding this matter. It is preferable to undertake such studies in specific zones, depending on geologic conditions, terrain, and climate. The paper by Bai, Du, Kuang, and Cheng describes a risk-warning method and system related to the management of loess engineered slopes. In the following paper, Yang, Shen, Huang, Lee, Cheng, and Chen use the probability maps of landslide occurrence to predict road closure. Road closure attributed to landslides may cause large economic impacts and delay evacuation in case of disasters. Finally, three are papers dedicated to other aspects that can enhance economical optimization. Considerable work has been done developing models to facilitate the planning of earth-moving operations. Carefully planning services between construction sites and landfill sites is an important but complicated task. Lin, Hsie, Hsiao, Wu, and Cheng develop computer simulation methods and genetic algorithms, with the objective of minimizing the time for constructing an optimal dispatch model to implement a more suitable schedule for operating truck fleets. This paper presents a systematic approach for modeling the process of dispatching earth-moving trucks. The paper by Li and Zhang focuses on re-