Emergency Earthquake Routes; Part I, Criteria for Selection of Primary Routes; and Part II: Route Seismic Vulnerability Aspects
Year: 2005
Type: report
Abstract: The occurrence of a strong earthquake in Indiana or neighboring states, as has occurred in the past, has serious implications for the State Transportation System with respect to adequate response. The definition of Earthquake Emergency Routes for the State of Indiana became a priority for the Indiana Department of Transportation. These Emergency Routes take into account various aspects related to transportation including coverage of population and area and travel time along these routes, and issues related to structural and geotechnical seismic vulnerability of the roads and bridges along these routes. Part I of the overall study report formulates a multi-commodity maximal covering network design problem (MCNDP) for identifying critical routes, for earthquake response and to seismically retrofit bridges. In the MCNDP, routes are sought that minimize the total travel time over the selected routes and maximize the total population covered, subject to a budget constraint on bridge retrofitting costs on the selected routes. The problem is formulated as a twoobjective integer programming model and solved using the branch-and-cut module in the CPLEX optimizer. The model performance is analyzed using the transportation network in southwest Indiana. A problem reduction strategy is introduced to reduce computational times by recognizing that the critical routes are not usually circuitous. Thereby, the search for the critical routes for an origin-destination (O-D) pair is confined to a limited geographical region around it. To further reduce computational costs, the formulation is extended to incorporate valid inequalities that exploit the problem structure. Simulation studies are conducted to investigate the effects of varying the budget and the relative weights of the two objectives. Noninferior frontiers that illustrate the trade-offs between the conflicting objectives for different budgets are constructed to provide practical insights to decision-makers. The final selected routes in addition include constraints set by the Study Advisory Committee regarding specific roads to be included in the final set. Part II of the study report covers the structural and geotechnical seismic issues related to the definition of Earthquake Emergency Routes for the State of Indiana. Previous worldwide experience on bridge damage during strong earthquakes has influenced the bridge earthquake design specifications and mitigation procedures. The evolution of the relevant requirements in the AASHTO Specifications and the existence of a proposed draft seismic design specification under development as part of the NCHRP Project 12-49 have significant implications in the assessment of the existing vulnerability, its mitigation, and the design of new
Authors: Julio Ramirez, Srinivas Peeta, Mete Sozen
Language: English
Subfield: Civil and Structural Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: gold
OpenAlex ID: W1564649771