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Hurricane Katrina caused significant damage to the transportation system in the Gulf Coast region. The overall cost to repair or replace the bridges damaged during the hurricane is estimated at over $1 billion. This paper describes the observed damage patterns to bridges, including damage attributed to storm surge, wind, impact from debris, scour, and water inundation, as well as examples of repair measures used to quickly restore functionality to the bridges and transportation system. Using the data from the 44 bridges that were damaged, relationships between storm surge elevation, damage level, and repair costs are developed. The analysis reveals that, in general, regions with higher storm surge had more damage, although there were several instances where this was not the case, primarily due to damage resulting from debris impact. It is also shown that a highly nonlinear relationship exists between the normalized repair cost and the damage state. The paper concludes with a brief discussion on the efficacy of using typical seismic design details for mitigating the effects of hurricane loads, and potential design considerations for bridge structures in vulnerable coastal regions.

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We report a quantum ring-like toroidal cavity naturally formed in a vertical-cavity-like active microdisk plane due to Rayleigh's band of whispering gallery modes. The √ T -dependent redshift and a square-law property of microampere-range threshold currents down to 2 µA are consistent with a photonic quantum wire view, due to whispering gallery mode-induced dimensional reduction.PACS number: 42.55. Sa, 42.60.Da For the last several years, there have been intensive developments of microdisk semiconductor lasers of whispering gallery(WG) modes for low-power and high-density photonic array applications. These efforts of earlier photo-pumped thumbtack-type WG lasers [1] have been evolving to photonic-wire lasers [2] and electro-pumped thumbtack-type WG lasers [3,4] of submilliampere threshold currents.In this letter, we demonstrate a cylindrical vertical-cavity surface-emitting laser(VCSEL)-like diode that exhibits WG modes with unusual photonic quantum ring(PQR) characteristics such as µA-range threshold currents and spectral √ Tdependence, in addition to the usual VCSEL mode. We will thus illustrate and analyze the two-threshold behavior of successive lasings, first the PQR and then the VC-SEL as well. Indeed, the quantum wire behavior of the PQR is vividly demonstrated in the √ T -dependent spectral peak shift data. We note that the quantum-ring-like WG modes are naturally formed in the circumferential Rayleigh band region [5] of the active microdisk of a regular multi-quantum-well VCSEL-like structure but without any intentional and real quantum ring patterning.The PQR device differs from the previous WG lasers [ [1][2][3][4]6] in that the vertical confinement is improved by the top and bottom DBR layers, and that stripe or segmented top electrodes are used for vertical output coupling. The metal-organic vapor-phase epitaxy-grown device employs a one-λ thick active layer with four 80 A Al 0.11 Ga 0.89 As quantum wells(QWs), whose details have been described elsewhere [8,9,12]. In the active disk plane, the PQR region is defined by Rayleigh's bandwidth, W Rayleigh = (φ/2)(1 − n ef f /n), where the WG mode occurs, which is well described in Ref. [7]: Rayleigh's annular band is defined by the active disk's radius R(= φ/2) for outer boundary and the inner reflection point r in = Rn M /n, where n is the refractive index of the active medium and n M is the effective refractive An exploded segment shows the effective toroidal structure of the PQR, where R is the index-guided outer limit and rin is the inner reflection limit which may also be reinforced by gain guiding. The radial evanescent field results from forward and backward helical traveling waves, and its intensity peaks at a distance t ≤ 1 µm from the outer boundary.The calculated profile of the annular WG emission based on Rayleigh's Bessel function analysis is shown in Fig. 1(a) for our device with R = 7.5 µm. The azimuthal mode number is rather large here, M = 2πRn ef f /λ = 188, and hence the 376 azimuthal peaks are not well distinguishable, unlike the i...

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