On first arriving in Portland, I was a little taken aback by the Steel Bridge. It was larger and more dominating than I had imagined (yes, I had imagined what the bridges would look like, my wife thinks it’s part of my charm, so don’t say anything), and not exactly aesthetically pleasing.But the Steel Bridge might be one of the ultimate examples of function over form. While it is only the second-oldest operating vertical lift bridge in the world (it is barely younger than the oldest in the world, the nearby Hawthorne Bridge), it is the only vertical lift bridge with a lower deck that can be raised independently of the upper deck. This allows the lower deck, with barely 25 feet clearance above the Willamette River, to be telescoped up into the upper deck to give room for river traffic to pass, without disrupting traffic on the upper deck. When a ship needs more clearance, both decks can be raised even higher (but traffic is completely stopped in this case, of course).
Speaking of traffic, the Steel Bridge is accommodates virtually every mode of transportation: freight rail, passenger rail, light rail, buses, automobiles, cyclists and pedestrians. The lower deck carries the Union Pacific rails, also used by Amtrak. A recent addition to the lower deck is a pedestrian walkway connecting the Eastbank Esplanade to Tom McCall Waterfront Park (the upper deck also has pedestrian walks, but they connect to the street grid several blocks beyond the river). The upper deck also carries rail traffic, in the form of MAX light rail, and has lanes to accommodate autos. This is all pretty damn impressive for a bridge built in 1912, especially one with so many complex moving parts. Oddly enough, the Steel Bridge is actually made of wrought iron, an unusual choice for bridge building at the time. The span it replaced, however, was named the Steel Bridge (and was made of steel), so the name just got placed onto the new bridge. Much like the Hawthorne Bridge, it has two impressive towers which hold the counterweights. These essentially balance the liftable portions of the bridge, dropping as the bridge rises and vice-versa. This means a relatively small motor can do the work of lifting the huge bridge sections over 100 feet in the air. Good stuff.
By the way, if you are a bridge geek like myself and were intrigued by the diagram to the right, the Library of Congress has all kinds of technical drawings of the Steel Bridge (and the other historic Willamette River bridges) online. Created for the Historic American Engineering Record, they are detailed glimpses of the more technical side of the bridges cross every day in Portlandia.