Pop quiz: Can you name the longest historical bridge over Arizona's Gila River?

Give up?

It was the relatively unassuming Bylas Bridge on US Highway 70 in Graham County, near the community of the same name. It was 1,800 feet long and a culmination of many attempts to span the river.

The Gila River has been an issue for Arizona's bridge builders for a long time. It could go from a mere trickle to a huge flood – and back – in the same day. More money and time were spent building and maintaining bridges over this waterway than any other in Arizona. Among them were the Antelope Hill, McPhaul and the Gillespie bridges. Engineers were determined not to let the river's unpredictable nature hold them back.

The Bylas Bridge was designed in 1956 by the Arizona Highway Department. It consists of 23 equal-length spans, with the I-beam steel stringer superstructure carried by concrete abutments and bullnosed piers. Each span extended 80 feet, for a total length of 1,829 feet. The concrete substructure - the bit under the actual driving surface - rested on steel piles driven beneath the riverbed. The concrete deck was 35 feet wide and flanked on both sides by aluminum baluster guardrails with concrete bulkheads. Construction was completed in 1957.

After its completion, the Bylas Bridge carried mainline traffic on US 70 for decades essentially unchanged. In the 1980s, bank and pier-scour protection was done. In 2000 the bridge received minor repairs to the steelwork. 

Unfortunately, by the early 2010s it had become "functionally obsolete."  Simply put, the bridge was just too narrow and in no condition to support modern traffic needs. So in 2012, ADOT began a replacement project, which built a new bridge alongside the historical structure. The old bridge was then demolished in 2013. 

Though it's now long gone, and it didn't have the aesthetic touches of some other bridges, the original Bylas Bridge played an important role in getting traffic across the troublesome Gila River. Add in its trememdous length and you have a structure that's definitely worth remembering.