Abstract

After over a decade of debate, construction of the San Francisco-Oakland Bay Bridge’s eastern span finally began in 2002 at a current approximate cost estimate of $6 billion. The intense and controversial debate ranged from whether the bridge should be seismically retrofitted or replaced, how it should be designed, where it should be located, and how it should be funded. Decisions on these issues provided fertile ground for a highly contested process as public agencies at every level of government and mobilized groups and citizens participated and significantly altered the decisionmaking process. The design process also signified a fundamental change in how state and regional agencies plan and manage projects of this magnitude. This dissertation provides a detailed history and analysis of the new span’s state and regional decisionmaking processes.

To guide this case study of a major transportation infrastructure project (also known as a “megaproject”), the research questions addressed are: What are the key characteristics and issues of debate for a major infrastructure project, such as the new Bay Bridge, and how do these impact policy decisions and project outcomes? These questions were designed to set the Bay Bridge case within a larger theoretical context while at the same time allowing the analysis to be of practical interest. This research contributes to the literature by knitting together the themes of megaproject planning, problem definition, agenda setting and policy implementation, as well as the “technological sublime,” which details how large scale projects capture the public’s attention and imagination. For the analysis, a megaproject typology and a conceptual framework focusing on megaproject characteristics and results are developed and applied to the Bay Bridge case. Lastly, several recurring themes throughout the bridge’s development process are examined, including substantial conflicts over the project’s purpose and definition; varying perceptions of crisis; and, disputes over accountability for cost overruns and delay that impeded the project’s implementation.

Abstract

The origin-destination (O-D) trip table is a key input required for traffic assignment and simulation models utilized to analyze a wide variety of transportation applications. The main goal of this research is to develop an economical and quick method for estimating O-D trip tables from traffic counts. Path flow estimator (PFE), originally developed by Bell and Shield (1995), has been further developed to improve the reliability and efficiency of O-D trip table estimates. The research reported herein includes only the development of the steady-state O-D estimator. In this study, the original PFE model was carefully examined in several aspects to gain more insight for further improvements. Currently, the PFE has been successfully applied to estimate the steady-state O-D trip tables for the Irvine Testbed network in Orange County, California as well as some other real networks. The primary results demonstrate that PFE has the capability to correctly estimate the total and individual O-D demands when proper information is provided. They also indicate that the number and locations of traffic counts significantly influence the quality of O-D estimates as each observation contributes different amount and quality of information.  The most difficult task observed thus far is the estimation of spatial pattern of O-D demands even when traffic counts were collected on all network links.  These issues and the development of time-dependent PFE will be investigated in the second phase under Task Order 5502.