vital artery for the city, the bridge s overall condition was rated poor. an inspection by the pennsylvania department of transportation last september. the city s fire chief said this collapse took everyone by surprise. we do have people go out and inspect the bridges. if there was any warning or concern, we would have been notified and we would have made sure that we didn t use this route. reporter: and were it not for poor weather conditions, it could have been very different. we were fortunate there was a public school delay and the traffic could have been much more pronounced. we re the city of bridges. and how many others are out there? reporter: and you can just make out the scene behind me here. you can see the red port authority bus. we re keeping our distance so we don t get in the way of first responders. the investigation into the cause of the collapse is just getting underway with the national transportation safety board