The history of the infrastructure of Pittsburgh bridges

This paper is 500 words long and your topic is an example of the infrastructure of your chosen city. You should describe what is there now, and include some background on what existed before this infrastructure was completed. If you are discussing a transit system (buses, rail or subway) what sort of transportation was there before the current ones? Or, if you are looking into a water or sewerage system (or both) what existed before this system was completed? Or, if you are writing about the electrification of the city, how was the decision made to begin this service? Was your chosen infrastructure a system of roads, bridges and/or highways? Was your infrastructure run by a private company or by the government or a combination of both? Did this governance change over time? What were the needs of the city that made this infrastructure necessary? What other ideas had they used before or considered? How was this designed? Who built or engineered it? How was it paid for? Has it been improved since it first began?