Quantification of Downtime in a Highway Network during Seismic Events
This study aims at quantifying the losses occurring in a highway network due to low ground motion intensities which causes non-structural damage resulting in short duration of bridge closure. In a highway network, the bridges are the most vulnerable elements and structural damage on the bridges give rise to a huge amount of economic loss due to repair and downtime. Research efforts were put to quantify these losses for large earthquakes causing the bridges to close for long period of time. Estimating the impact of low ground motion intensity that do not cause any structural damage rather short duration of disruption owing to non-structural damage and inspection is investigated in this study. The focus is on quantifying short downtime of bridges in terms of economic losses and assessing the impact these events have in the broad picture.
The study involves probabilistic seismic hazard analysis at the bridge sites of the SR-91 highway network and create earthquake scenarios and concurrently conduct traffic simulation to estimate the delay in the network. The traffic simulations are carried out in TransModeller for different scenarios considering two durations of bridge closure: half-hour and two-hour. The delay in the network is converted to monetary loss as per the cost analysis parameters by Caltrans. The economic loss for the specific cases of ground motion lies in the range of $1.5 million to $4.5 million with a 15-year return period.