The city digital twin is anticipated to accurately reflect and affect the city’s functions and processes to enhance its realization, operability, and management. Although research on the city digital twin is still in its infancy, the advancement of the digital twin technology is growing fast and providing viable contributions to augmenting smart city developments. This study reviews the literature to identify the current and prospective potentials and challenges of digital twin cities. A research agenda is also proposed to guide future research on the city digital twincity digital twin to reach the utmost level of a comprehensive and complete city digital twin. Enhancing the efficiency of data processing, promoting the inclusion of socio-economic components of the city, and developing mutual integration between the two counterparts of the digital twin are proposed to be the future research directions to achieve and utilize a completely mirrored city digital twin.

Due to rapid urbanization and the recent growing influx of migrants from politically fragile states, cities are now faced with an impending housing problem. In developing countries like Nigeria, the impacts of the housing problem, which include economic, social (humanitarian), and environmental crises, are evident. Recently, sustainability has become a central theme for public discussion, not only in expanding housing for the growing population but also in improving the quality of residential livelihoods of low-income households without compromising the housing needs of future generations. So far, there have been numerous studies conducted on sustainable housing in Nigeria, touching on sustainability in housing but mostly from the professionals’ point of view. Therefore, a document content analysis to generate success criteria and a survey for household validation were conducted. Results show that security ranks the highest, and other criteria of importance include accessibility, adaptability, utility, technology, community, affordability, and acceptability. Hence, the study concludes that social and environmental sustainability in housing should enhance household satisfaction by ensuring the security and welfare of its residents, adapt to its immediate environment, be acceptable, be supported with social amenity to integrate the community through participation, and, finally, manage household utility efficiently.

This study provides a methodology for calibrating freeway work zone capacity in a microsimulation environment and guidance for replicating field-observed freeway work zone capacity through simulation. From 81 field observations at 12 U.S. work zone sites, 90 work zone sites from literature archival sources, and a macroscopic capacity model developed in NCHRP Project 03-107, the authors show how to replicate field-observed or forecast capacity in the Vissim simulation tool under various scenarios of freeway work zone lane closure. With guidance from an in-depth literature review, key car-following and lane-changing parameters are proposed as a result of the calibration effort and extensive sensitivity tests of numerous combinations of parameter values. Lane configuration specific guidance is provided for two key car-following parameters in Vissim, cc1 and cc2. During the process of developing the guidance, every tested capacity scenario was verified by using a lane use volume balance that was obtained upstream of the lane closure point in order to replicate realistic freeway work zone conditions. The calibration methodology as well as default parameter guidance developed through this research are useful to practitioners who wish to model freeway work zone impacts accurately through microsimulation.

In response to minimum retroreflectivity standards, transportation departments are implementing sign asset management strategies, which rely upon knowledge of how retroreflectivity decreases as signs weather and age. To provide this knowledge, the authors field-measured over 1000 inservice signs in scattered North Carolina Department of Transportation (NCDOT) divisions, collecting age and retroreflectivity data for white, yellow, red, and green signs and for ASTM sheeting Types I and III. Data from this study and data from five similar US efforts were analyzed using regression to identify the best available deterioration rate estimates, finding that retroreflectivity minimums are usually reached 8 to 15 years after installation.Initial results indicated that the best-fitting relationships between retroreflectivity and age were generally linear and that these models were significant despite having low R 2 values. Because age did not explain some of the variance, the authors re-evaluated their data including NCDOT divisions as a factor, finding that sign deterioration differed significantly by division, indicating that handling practices, manufacturing differences, and environmental exposure may be key deterioration model factors that merit future study.

Delays in road construction projects due to various reasons are a major problem facing construction professionals. The incapability of finishing projects punctually and within a given budget is a persistent issue worldwide. This study aims to determine the ten principal causes of delay in road construction projects in 25 developing countries across the globe. The study involves two steps. First, the authors compiled information regarding the most frequent delays in a road construction project. Second, they analyzed the intensity of each cause of delay in these projects. Being more accurate in the methodology, given the nature of the information, the researchers used a quasi-meta-analysis for processing the data. Half (50%) of the countries have similar causes of delay, and likewise, 50% of the countries identified the top ten primary causes of delay in road construction projects based on the intensity results. This study uses the results of the intensity. According to the results of the homologation, the lack of experience of the construction manager, inadequate planning/scheduling, and influence on people’s land alongside the road construction project (expropriation for the construction of the project) have more significant impacts than frequent changes in the design (which was listed as the most frequent cause of delay).