|Project Title/ID Number||Seismic Hazard Simulation of Bay Area Highway Network Analysis—3222002|
|Project Leader||James Moore (USC/Faculty)|
|Team Members||Yue Yue Fan (USC/Grad Student), Sungbin Cho (USC/Grad Student), Qisheng Pan (USC/Grad Student), Soojung Kim (USC/Grad Student), Dongwhan An (USC/Grad Student), Deepali Chausalkar (USC/Grad Student)|
|Project goals and objectives|
The goals of the PEER Seismic Hazard Simulation of Bay Area Highway Network Transportation Analysis are to develop appropriate analytical and computational methods for evaluating the impact of a transportation system on an urban area and to illustrate the utility of these methods through an application to a region. In general, risk analysis of highway transportation systems is performed with the objective to provide:
Linking models of network performance, transportation demand, bridge performance, and seismic hazard are the key to this effort.
One of the main objectives of this project is to apply the methodology to the Bay Area highway transportation system. During the first PEER Transportation Risk Analysis Workshop held in 1998, the workshop participants recommended that the application area be the San Francisco Bay region. The rationale for the selection was that the region has a very complex transportation network with limited redundancy. In particular, it is very likely that the major bridges in the region will be subjected to ground motions of similar severity due to their proximity to major faults in the area. All the long-span bridges, the San Francisco-Oakland Bay Bridge, Golden Gate, San Mateo, Dumbarton and San Rafael, are flanked by the San Andreas Fault to the west and the Hayward fault or its extension to the east.
|Role of this project in supporting PEER’s vision|
PEER’s System Vision identifies three levels of decision making supported by Performance-Based Earthquake Engineering:
The objective of this
research is to determine how to make design decisions about transportation
networks that reflect specific
objectives. The ultimate goal of this research is to support
decisions in the second and third categories. In an infrastructure
decisions of the second and third types interact, with infrastructure
in the executive branch making recommendations to commissions
and legislatures, which in term make funding allocation and
burden decisions in response
to these and other recommendations.
Nonlinear programming (for network equilibrium analysis and gravity model estimation), economic modeling, and trial and error.
|Brief description of past year’s accomplishments and more detail on expected Year 6 accomplishments|
Three major tasks have been accomplished over the past year. These are update of the MTC highway network, improvement of the traffic assignment model, and sensitivity study of the bridge closure criteria.
1. Update of Network and Demand Data
2. Improvement of the Traffic Assignment Model
The modified network level of service in the earthquake scenario results to account for changes in the transportation demand between each origin-destination zone pair. Figure 2 shows the pattern of redistribution of the travel demand.
2: Proportionate Difference in Trip Production,
Variable vs. Fixed Demand Models
3. Sensitivity Study of Bridge Closure Criteria
The ultimate product of our research is intended to be tools for decision support. Decisions concerning seismic risks to transportation networks must be made both before and after earthquakes. Pre-event decisions focus on allocation of resources to retrofit, construction, and network design options. Post-event decisions focus on resource allocation to repair, reconstruction, replacement, and capacity management options.
Retrofitting or reconstruction facilities prior to an earthquake can best summarized as an exercise in stochastic network design. Given scarce resources, which links in the network should be improved to best mitigate uncertain seismic risks to system performance? This is obviously a very challenging question. Deterministic network design problems involving such discrete investments are well investigated, and standard approaches have been developed. Stochastic network design problems have been stated, but have not been treated analytically beyond the level of toys. Still, public agencies in seismically active areas cannot afford to ignore this question. Every seismic event results in temporary opportunities for public authorities to intensify public investments in the mitigation of seismic risk, and this includes the stochastic network design decisions that are made every time a transportation structure is retrofitted.
Post-event decisions have the advantage of being deterministic, because they take place after the random events of an earthquake have been realized. They have the disadvantage of being very large problems. Sequencing repairs to hundreds or even just dozens of earthquake-damaged bridges in the SF Bay Area network is a far larger network design problem than is normally encountered in engineering practice. The challenge exceeds the reach of available methodologies. Still public authority cannot afford to ignore the problem, because the problem will confront us in the foreseeable future.
|Other similar work being conducted within and outside PEER and how this project differs|
In previous research funded by NSF and PEER,
we have specified a computable model that shows the effects of earthquakes
on transportation networks, building stocks, and regional economic activities.
This model accounts for interactions between the urban economy and the
|Plans for Year 7 if this project is expected to be continued|
|Describe any instances where you are aware that your results have been used in industry|
The project team will normally participate in scientific meetings organized by PEER, and acknowledge PEER sponsorship in any papers published as a result of this research.
Year 5 research activity will conclude March 31, 2003. Deliverables associated with PEER project 3222001 include brief reports submitted at intervals defined by PEER, and a comprehensive final report at the conclusion of the project. The final report will be coordinated with the final report document provided by the Stanford team.