The purpose of this research is to assist the NCDOT Traffic Management Unit (TMU) and the Value Management Office (VMO) in assessing issues regarding the construction of Diverse, Modern, and Unconventional Intersections and Interchanges (DMUII). Assessing the constructability of these emerging DMUII is a new area of study that has not yet been previously explored. Therefore, this research will identify factors affecting construction projects prior to construction and develop a schedule and cost payout model (based on prior NCDOT projects) that identifies problems related to expenditure, schedule, and obstruction of traffic during construction.
A major problem with modern designs is that contractors perceive them to result in additional time and cost compared to projects for conventional designs. Modern designs are also often unfamiliar and bring unique challenges. Therefore, it is important for NCDOT to assess this. If modern designs are indeed requiring additional time to be constructed, the exact reasons for this additional time need to be identified in order to present an optimal design. If these designs do not result in additional time and cost, evidence needs to be presented to recommend the use of modern designs over conventional where appropriate.
This study answers the question “what constructability practices could be adopted that would enhance the construction of DMUII?" This study will explore whether problems related to expenditures, schedule, traffic flow, and work zone safety during construction could be addressed and best practices can be implemented by any division within North Carolina to enhance performance, reduce time and cost, and be realistically and efficiently implemented.
We hope to identify a well-founded set of best constructability innovations that appropriately address when construction problems will and do occur and help identify those problems as quickly as possible so that corrective actions can be undertaken to mitigate cost and schedule damage. In addition, we will assess the effectiveness of 4D (time/schedule added to 3D geometry) model techniques as an innovation for constructability enhancements, to assess traffic flow, to aid us in determining areas of conflict, and to find possible problems with cost, schedule, and space constraints. These will then be used by NCDOT to identify constructability issues in advance to reduce costs and enhance delivery and safety.
The essential research questions are the following. (1) How to solve construction problems related to building DMUIIs without incurring cost increases, schedule delays, or congestion? (2) What is the difference with respect to time and cost between conventional projects versus unconventional projects? (3) What are the challenging constructability issues facing the DMUII designs used in NC?
To answer these questions the research team will collaborate with the NCDOT TMU and with other NCDOT personnel as appropriate. We will also closely examine the characteristics of DMUIIs using various models that would enable us to examine more DMUIIs than we could with pilot studies. This will include 4D modeling (one of many potential constructability innovations) to aid in determining areas of conflicts, possible problems with cost and budgets, and issues with construction activity sequencing. We propose to compile, assess, and quantify effectiveness, compliance, and cost savings resulting from this investigation.
The lessons learned from the assessment and analysis will be derived from the experiences of NC divisions, from knowledge extracted from the literature, from case studies of previous and current projects, from the HiCAMs database, and from the wealth of data obtained from past and current constructability reviews. These will be used to formulate new strategies to meet NCDOT needs.